ip assignment table

Understanding IP Address Assignment: A Complete Guide

Introduction

In today's interconnected world, where almost every aspect of our lives relies on the internet, understanding IP address assignment is crucial for ensuring online security and efficient network management. An IP address serves as a unique identifier for devices connected to a network, allowing them to communicate with each other and access the vast resources available on the internet. Whether you're a technical professional, a network administrator, or simply an internet user, having a solid grasp of how IP addresses are assigned within the same network can greatly enhance your ability to troubleshoot connectivity issues and protect your data.

The Basics of IP Addresses

Before delving into the intricacies of IP address assignment in the same network, it's important to have a basic understanding of what an IP address is. In simple terms, an IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It consists of four sets of numbers separated by periods (e.g., 192.168.0.1) and can be either IPv4 or IPv6 format.

IP Address Allocation Methods

There are several methods used for allocating IP addresses within a network. One commonly used method is Dynamic Host Configuration Protocol (DHCP). DHCP allows devices to obtain an IP address automatically from a central server, simplifying the process of managing large networks. Another method is static IP address assignment, where an administrator manually assigns specific addresses to devices within the network. This method provides more control but requires careful planning and documentation.

Considerations for Efficient IP Address Allocation

Efficient allocation of IP addresses is essential for optimizing network performance and avoiding conflicts. When assigning IP addresses, administrators need to consider factors such as subnetting, addressing schemes, and future scalability requirements. By carefully planning the allocation process and implementing best practices such as using private IP ranges and avoiding overlapping subnets, administrators can ensure smooth operation of their networks without running out of available addresses.

IP Address Assignment in the Same Network

When two routers are connected within the same network, they need to obtain unique IP addresses to communicate effectively. This can be achieved through various methods, such as using different subnets or configuring one router as a DHCP server and the other as a client. Understanding how IP address assignment works in this scenario is crucial for maintaining proper network functionality and avoiding conflicts.

Basics of IP Addresses

IP addresses are a fundamental aspect of computer networking that allows devices to communicate with each other over the internet. An IP address, short for Internet Protocol address, is a unique numerical label assigned to each device connected to a network. It serves as an identifier for both the source and destination of data packets transmitted across the network.

The structure of an IP address consists of four sets of numbers separated by periods (e.g., 192.168.0.1). Each set can range from 0 to 255, resulting in a total of approximately 4.3 billion possible unique combinations for IPv4 addresses. However, with the increasing number of devices connected to the internet, IPv6 addresses were introduced to provide a significantly larger pool of available addresses.

IPv4 addresses are still predominantly used today and are divided into different classes based on their range and purpose. Class A addresses have the first octet reserved for network identification, allowing for a large number of hosts within each network. Class B addresses reserve the first two octets for network identification and provide a balance between network size and number of hosts per network. Class C addresses allocate the first three octets for network identification and are commonly used in small networks.

With the depletion of available IPv4 addresses, IPv6 was developed to overcome this limitation by utilizing 128-bit addressing scheme, providing an enormous pool of potential IP addresses - approximately 3.4 x 10^38 unique combinations.

IPv6 addresses are represented in hexadecimal format separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The longer length allows for more efficient routing and eliminates the need for Network Address Translation (NAT) due to its vast address space.

Understanding these basics is essential when it comes to assigning IP addresses in a network. Network administrators must consider various factors such as the number of devices, network topology, and security requirements when deciding on the IP address allocation method.

In the next section, we will explore different methods of IP address assignment, including Dynamic Host Configuration Protocol (DHCP) and static IP address assignment. These methods play a crucial role in efficiently managing IP addresses within a network and ensuring seamless communication between devices.

Methods of IP Address Assignment

IP address assignment is a crucial aspect of network management and plays a vital role in ensuring seamless connectivity and efficient data transfer. There are primarily two methods of assigning IP addresses in a network: dynamic IP address assignment using the Dynamic Host Configuration Protocol (DHCP) and static IP address assignment.

Dynamic IP Address Assignment using DHCP

Dynamic IP address assignment is the most commonly used method in modern networks. It involves the use of DHCP servers, which dynamically allocate IP addresses to devices on the network. When a device connects to the network, it sends a DHCP request to the DHCP server, which responds by assigning an available IP address from its pool.

One of the key benefits of dynamic IP address assignment is its simplicity and scalability. With dynamic allocation, network administrators don't have to manually configure each device's IP address. Instead, they can rely on the DHCP server to handle this task automatically. This significantly reduces administrative overhead and makes it easier to manage large networks with numerous devices.

Another advantage of dynamic allocation is that it allows for efficient utilization of available IP addresses. Since addresses are assigned on-demand, there is no wastage of unused addresses. This is particularly beneficial in scenarios where devices frequently connect and disconnect from the network, such as in public Wi-Fi hotspots or corporate environments with a high turnover rate.

However, dynamic allocation does have some drawbacks as well. One potential issue is that devices may receive different IP addresses each time they connect to the network. While this might not be an issue for most users, it can cause problems for certain applications or services that rely on consistent addressing.

Additionally, dynamic allocation introduces a dependency on the DHCP server. If the server goes down or becomes unreachable, devices will not be able to obtain an IP address and will be unable to connect to the network. To mitigate this risk, redundant DHCP servers can be deployed for high availability.

Static IP Address Assignment

Static IP address assignment involves manually configuring each device's IP address within the network. Unlike dynamic allocation, where addresses are assigned on-demand, static assignment requires administrators to assign a specific IP address to each device.

One of the main advantages of static IP address assignment is stability. Since devices have fixed addresses, there is no risk of them receiving different addresses each time they connect to the network. This can be beneficial for applications or services that require consistent addressing, such as servers hosting websites or databases.

Static assignment also provides greater control over network resources. Administrators can allocate specific IP addresses to devices based on their requirements or security considerations. For example, critical servers or network infrastructure devices can be assigned static addresses to ensure their availability and ease of management.

However, static IP address assignment has its limitations as well. It can be time-consuming and error-prone, especially in large networks with numerous devices. Any changes to the network topology or addition/removal of devices may require manual reconfiguration of IP addresses, which can be a tedious task.

Furthermore, static allocation can lead to inefficient utilization of available IP addresses. Each device is assigned a fixed address regardless of whether it is actively using the network or not. This can result in wastage of unused addresses and may pose challenges in scenarios where addressing space is limited.

In order to efficiently allocate IP addresses within a network, there are several important considerations that need to be taken into account. By carefully planning and managing the allocation process, network administrators can optimize their IP address usage and ensure smooth operation of their network.

One of the key factors to consider when assigning IP addresses is the size of the network. The number of devices that will be connected to the network determines the range of IP addresses that will be required. It is essential to accurately estimate the number of devices that will need an IP address in order to avoid running out of available addresses or wasting them unnecessarily.

Another consideration is the type of devices that will be connected to the network. Different devices have different requirements in terms of IP address assignment. For example, servers and other critical infrastructure typically require static IP addresses for stability and ease of access. On the other hand, client devices such as laptops and smartphones can often use dynamic IP addresses assigned by a DHCP server.

The physical layout of the network is also an important factor to consider. In larger networks with multiple subnets or VLANs, it may be necessary to segment IP address ranges accordingly. This allows for better organization and management of IP addresses, making it easier to troubleshoot issues and implement security measures.

Security is another crucial consideration when allocating IP addresses. Network administrators should implement measures such as firewalls and intrusion detection systems to protect against unauthorized access or malicious activities. Additionally, assigning unique IP addresses to each device enables better tracking and monitoring, facilitating quick identification and response in case of any security incidents.

Efficient utilization of IP address ranges can also be achieved through proper documentation and record-keeping. Maintaining an up-to-date inventory of all assigned IP addresses helps prevent conflicts or duplicate assignments. It also aids in identifying unused or underutilized portions of the address space, allowing for more efficient allocation in the future.

Furthermore, considering future growth and scalability is essential when allocating IP addresses. Network administrators should plan for potential expansion and allocate IP address ranges accordingly. This foresight ensures that there will be sufficient addresses available to accommodate new devices or additional network segments without disrupting the existing infrastructure.

In any network, the assignment of IP addresses is a crucial aspect that allows devices to communicate with each other effectively. When it comes to IP address assignment in the same network, there are specific considerations and methods to ensure efficient allocation. In this section, we will delve into how two routers in the same network obtain IP addresses and discuss subnetting and IP address range distribution.

To understand how two routers in the same network obtain IP addresses, it's essential to grasp the concept of subnetting. Subnetting involves dividing a larger network into smaller subnetworks or subnets. Each subnet has its own unique range of IP addresses that can be assigned to devices within that particular subnet. This division helps manage and organize large networks efficiently.

When it comes to assigning IP addresses within a subnet, there are various methods available. One common method is manual or static IP address assignment. In this approach, network administrators manually assign a specific IP address to each device within the network. Static IP addresses are typically used for devices that require consistent connectivity and need to be easily identifiable on the network.

Another widely used method for IP address assignment is Dynamic Host Configuration Protocol (DHCP). DHCP is a networking protocol that enables automatic allocation of IP addresses within a network. With DHCP, a server is responsible for assigning IP addresses dynamically as devices connect to the network. This dynamic allocation ensures efficient utilization of available IP addresses by temporarily assigning them to connected devices when needed.

When considering efficient allocation of IP addresses in the same network, several factors come into play. One important consideration is proper planning and design of subnets based on anticipated device count and future growth projections. By carefully analyzing these factors, administrators can allocate appropriate ranges of IP addresses for each subnet, minimizing wastage and ensuring scalability.

Additionally, implementing proper security measures is crucial when assigning IP addresses in the same network. Network administrators should consider implementing firewalls, access control lists (ACLs), and other security mechanisms to protect against unauthorized access and potential IP address conflicts.

Furthermore, monitoring and managing IP address usage is essential for efficient allocation. Regular audits can help identify any unused or underutilized IP addresses that can be reclaimed and allocated to devices as needed. This proactive approach ensures that IP addresses are utilized optimally within the network.

The proper assignment of IP addresses is crucial for maintaining network security and efficiency. Throughout this guide, we have covered the basics of IP addresses, explored different methods of IP address assignment, and discussed considerations for efficient allocation.

In conclusion, understanding IP address assignment in the same network is essential for network administrators and technical professionals. By following proper allocation methods such as DHCP or static IP assignment, organizations can ensure that each device on their network has a unique identifier. This not only enables effective communication and data transfer but also enhances network security by preventing unauthorized access.

Moreover, considering factors like subnetting, scalability, and future growth can help optimize IP address allocation within a network. Network administrators should carefully plan and allocate IP addresses to avoid conflicts or wastage of resources.

Overall, a well-managed IP address assignment process is vital for the smooth functioning of any network. It allows devices to connect seamlessly while ensuring security measures are in place. By adhering to best practices and staying updated with advancements in networking technology, organizations can effectively manage their IP address assignments.

In conclusion, this guide has provided a comprehensive overview of IP address assignment in the same network. We hope it has equipped you with the knowledge needed to make informed decisions regarding your network's IP address allocation. Remember that proper IP address assignment is not only important for connectivity but also plays a significant role in maintaining online security and optimizing network performance.

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IANA IPv4 Address Space Registry

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About the Online Subnet Calculator

Network administrators have been using subnetting for decades to make their networks manageable. Subnets allow you to break large networks into smaller subnets , which are logically separated. If something goes wrong in one part of the network, it does not affect other segments.

The design of IP addressing means every time you add a bit to your subnet mask, you divide the subnet in two parts and assign separate networks. This allows you to build and maintain scalable and efficient networks.

Network Calculator and Free API

This online subnet calculator is the perfect tool to help you figure out out what a network address will be or calculate subnets with masks. This online calculator helps you determine whether a network has enough hosts. also provides an easy way of translating between CIDR notation and dotted-decimal format if needed.

Enter your subnet to get the subnet mask, wildcard mask, network/broadcast address, and number of assignable hosts. You can edit the results and save them on an IP address table and print them for reference.

Use the free subnet API to calculate subnets from a terminal or integrate with software. Save a subnet to your NetworkCalc account to manage IP address assignments.

We designed these tools for systems administrators, network engineers, IT specialists, and students. We hope you find them valuable!

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What would happen if you told someone that you lived at 34 Elm Street, and when that person turned onto your road found four different houses with the number “34” on them? They'd probably find your place eventually but wouldn't be too pleased. Neither would you or your mail carrier. J And all of you folks are much smarter than computers. Where I am going with this is that like street addresses, IP addresses must be unique for them to be useful.

Since IP datagrams are sent only within the confines of the IP internetwork, they must be unique within each internetwork. If you are a company with your own private internetwork, this isn't really a big problem. Whoever is in charge of maintaining the internetwork keeps a list of what numbers have been used where and makes sure that no two devices are given the same address. However, what happens in a public network with many different organizations? Here, it is essential that the IP address space be managed across the organizations to ensure that they use different addresses. It's not feasible to have each organization coordinate its activities with each other one. Therefore, some sort of centralized management authority is required.

At the same time that we need someone to ensure that there are no conflicts in address assignment, we don't want every user of the network to have to go to this central authority every time they need to make a change to their network. It makes more sense to have the authority assign numbers in blocks or chunks to organizations based on the number of devices they want to connect to the network. The organizations can manage those blocks as they see fit, and the authority's job is made easier because it deals in blocks instead of billions of individual addresses and machines.

Subnet Cheat Sheet – 24 Subnet Mask, 30, 26, 27, 29, and other IP Address CIDR Network References

As a developer or network engineer, you may need to occasionally look up subnet mask values and figure out what they mean.

To make your life easier, the freeCodeCamp community has made this simple cheat sheet. Just scroll or use Ctrl/Cmd + f to find the value you're looking for.

Here are the charts, followed by some explanations of what they mean.

* /31 is a special case detailed in RFC 3021 where networks with this type of subnet mask can assign two IP addresses as a point-to-point link.

And here's a table of the decimal to binary conversions for subnet mask and wildcard octets:

Note that the wildcard is just the inverse of the subnet mask.

If you are new to network engineering, you can get a better idea of how computer networks work here .

Finally, this cheat sheet and the rest of the article is focused on IPv4 addresses, not the newer IPv6 protocol. If you'd like to learn more about IPv6, check out the article on computer networks above.

How Do IP Address Blocks Work?

IPv4 addresses like 192.168.0.1 are really just decimal representations of four binary blocks.

Each block is 8 bits, and represents numbers from 0-255. Because the blocks are groups of 8 bits, each block is known as an octet . And since there are four blocks of 8 bits, every IPv4 address is 32 bits.

For example, here's what the IP address 172.16.254.1 looks like in binary:

To convert an IP address between its decimal and binary forms, you can use this chart:

The chart above represents one 8 bit octive.

Now lets say you want to convert the IP address 168.210.225.206 . All you need to do is break the address into four blocks ( 168 , 210 , 225 , and 206 ), and convert each into binary using the chart above.

Remember that in binary, 1 is the equivalent to "on" and 0 is "off". So to convert the first block, 168 , into binary, just start from the beginning of the chart and place a 1 or 0 in that cell until you get a sum of 168 .

For example:

128 + 32 + 8 = 168, which in binary is 10101000 .

If you do this for the rest of the blocks, you'd get 10101000.11010010.11100001.11001110 .

What is Subnetting?

If you look at the table above, it can seem like the number of IP addresses is practically unlimited. After all, there are almost 4.2 billion possible IPv4 addresses available.

But if you think about how much the internet has grown, and how many more devices are connected these days, it might not surprise you to hear that there's already a shortage of IPv4 addresses .

Because the shortage was recognized years ago, developers came up with a way to split up an IP address into smaller networks called subnets.

This process, called subnetting, uses the host section of the IP address to break it down into those smaller networks or subnets.

Generally, an IP address is made up of network bits and host bits:

So generally, subnetting does two things: it gives us a way to break up networks into subnets, and allows devices to determine whether another device/IP address is on the same local network or not.

A good way to think about subnetting is to picture your wireless network at home.

Without subnetting, every internet connected device would need its own unique IP address.

But since you have a wireless router, you just need one IP address for your router. This public or external IP address is usually handled automatically, and is assigned by your internet service provider (ISP).

Then every device connected to that router has its own private or internal IP address:

Now if your device with the internal IP address 192.168.1.101 wants to communicate with another device, it'll use the IP address of the other device and the subnet mask.

The combination of the IP addresses and subnet mask allows the device at 192.168.1.101 to figure out if the other device is on the same network (like the device at 192.168.1.103 ), or on a completely different network somewhere else online.

Interestingly, the external IP address assigned to your router by your ISP is probably part of a subnet, which might include many other IP addresses for nearby homes or businesses. And just like internal IP addresses, it also needs a subnet mask to work.

How Subnet Masks Work

Subnet masks function as a sort of filter for an IP address. With a subnet mask, devices can look at an IP address, and figure out which parts are the network bits and which are the host bits.

Then using those things, it can figure out the best way for those devices to communicate.

If you've poked around the network settings on your router or computer, you've likely seen this number: 255.255.255.0 .

If so, you've seen a very common subnet mask for simple home networks.

Like IPv4 addresses, subnet masks are 32 bits. And just like converting an IP address into binary, you can do the same thing with a subnet mask.

For example, here's our chart from earlier:

Now let's convert the first octet, 255:

Pretty simple, right? So any octet that's 255 is just 11111111 in binary. This means that 255.255.255.0 is really 11111111.11111111.11111111.00000000 in binary.

Now let's look at a subnet mask and IP address together and calculate which parts of the IP address are the network bits and host bits.

Here are the two in both decimal and binary:

With the two laid out like this, it's easy to separate 192.168.0.101 into network bits and host bits.

Whenever a bit in a binary subnet mask is 1, then the same bit in a binary IP address is part of the network, not the host.

Since the octet 255 is 11111111 in binary, that whole octet in the IP address is part of the network. So the first three octets, 192.168.0 , is the network portion of the IP address, and 101 is the host portion.

In other words, if the device at 192.168.0.101 wants to communicate with another device, using the subnet mask it knows that anything with the IP address 192.168.0.xxx is on the same local network.

Another way to express this is with a network ID, which is just the network portion of the IP address. So the network ID of the address 192.168.0.101 with a subnet mask of 255.255.255.0 is 192.168.0.0 .

And it's the same for the other devices on the local network ( 192.168.0.102 , 192.168.0.103 , and so on).

What Does CIDR Mean and What is CIDR Notation?

CIDR stands for Classless Inter-Domain Routing, and is used in IPv4, and more recently, IPv6 routing.

CIDR was introduced in 1993 as a way to slow the usage of IPv4 addresses, which were quickly being exhausted under the older Classful IP addressing system that the internet was first built on.

CIDR encompasses a couple of major concepts.

The first is Variable Length Submasking (VLSM), which basically allowed network engineers to create subnets within subnets. And those subnets could be different sizes, so there would be fewer unused IP addresses.

The second major concept CIDR introduced is CIDR notation.

CIDR notation is really just shorthand for the subnet mask, and represents the number of bits available to the IP address. For instance, the /24 in 192.168.0.101/24 is equivalent to the IP address 192.168.0.101 and the subnet mask 255.255.255.0 .

How to Calculate CIDR Noation

To figure out the CIDR notation for a given subnet mask, all you need to do is convert the subnet mask into binary, then count the number of ones or "on" digits. For example:

Because there's three octets of ones, there are 24 "on" bits meaning that the CIDR notation is /24 .

You can write it either way, but I'm sure you'll agree that /24 is a whole lot easier to write than 255.255.255.0 .

This is usually done with an IP address, so let's take a look at the same subnet mask with an IP address:

The first three octets of the subnet mask are all "on" bits, so that means that the same three octets in the IP address are all network bits.

Let's take a look at the last forth octet in a bit more detail:

In this case, because all the bits for this octet in the subnet mask are "off", we can be certain that all of the corresponding bits for this octet in the IP address are part of the host.

When you write CIDR notation it's usually done with the network ID. So the CIDR notation of the IP address 192.168.0.101 with a subnet mask of 255.255.255.0 is 192.168.0.0/24 .

To see more examples of how to calculate the CIDR notation and network ID for a given IP address and subnet mask, check out this video:

Classful IP Addressing

Now that we've gone over some basic examples of subnetting and CIDR, let's zoom out and look at what's known as Classful IP addressing.

Back before subnetting was developed, all IP addresses fell into a particular class:

Note that there are class D and E IP addresses, but we'll go into these in more detail a bit later.

Classful IP addresses gave network engineers a way to provide different organizations with a range of valid IP addresses.

There were a lot of issues with this approach that eventually lead to subnetting. But before we get into those, let's take a closer look at the different classes.

Class A IP Addresses

For Class A IP addresses,  the first octet (8 bits / 1 byte) represent the network ID, and the remaining three octets (24 bits / 3 bytes) are the host ID.

Class A IP addresses range from 1.0.0.0 to 127.255.255.255 , with a default mask of 255.0.0.0 (or /8 in CIDR).

This means that Class A addressing can have a total of 128 (2 7 ) networks and 16,777,214 (2 24 -2) usable addresses per network.

Also, note that the range 127.0.0.0 to 127.255.255.255 within the Class A range is reserved for host loopback address (see RFC5735 ).

Class B IP Addresses

For Class B IP addresses, the first two octets (16 bits / 2 bytes) represent the network ID and the remaining two octets (16 bits / 2 bytes) are the host ID.

Class B IP addresses range from 128.0.0.0 to 191.255.255.255 , with a default subnet mask of 255.255.0.0 (or /16 in CIDR).

Class B addressing can have 16,384 (2 14 ) network addresses and 65,534 (2 16 ) usable addresses per network.

Class C IP Addresses

For Class C IP addresses, the first three octets (24 bits / 3 bytes) represent the network ID and the last octet (8 bits / 1 bytes) is the host ID.

Class C IP Addresses range from 192.0.0.0 to 223.255.255.255 , with a default subnet mask of 255.255.255.0 (or /24 in CIDR).

Class C translates to 2,097,152 (2 21 ) networks and 254 (2 8 -2) usable addresses per network.

Class D and Class E IP Addresses

The last two classes are Class D and Class E.

Class D IP addresses are reserved for multicasts. They occupy the range from 224.0.0.0 through 239.255.255.255 .

Class E IP addresses are experimental, and are anything over 240.0.0.0 .

The Issue with Classful IP Addresses

The main issue with classful IP addresses is that it wasn't efficient, and could lead to a lot of wasted IP addresses.

For example, imagine that you're part of a large organization back then. Your company has 1,000 employees, meaning that it would fall into class B.

But if you look above, you'll see that a class B network can support up to 65,534 usable addresses. That's way more than your organization would likely need, even if each employee had multiple devices with a unique address.

And there was no way your organization could fall back to class C – there just wouldn't be enough usable IP addresses.

So while classful IP addresses were used around the time IPv4 addresses became widespread, it quickly became clear that a better system would be necessary to ensure we wouldn't use up all of the ~4.2 billion usable addresses.

Classful IP addresses haven't been used since they were replaced by CIDR in 1993, and are mostly studied to understand early internet architecture, and why subnetting is important.

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Methods of Assigning IP Addresses

This section discusses methods of assigning IP addresses to end systems and explains their influence on administrative overhead. Address assignment includes assigning an IP address, a default gateway, one or more domain name servers that resolve names to IP addresses, time servers, and so forth. Before selecting the desired IP address assignment method, the following questions should be answered:

■ How many devices need an IP address?

■ Which devices require static IP address assignment?

■ Is IP address renumbering expected in the future?

■ Is the administrator required to track devices and their IP addresses?

■ Do additional parameters (default gateway, name server, and so forth) have to be configured?

■ Are there any availability issues?

■ Are there any security issues?

Static Versus Dynamic IP Address Assignment Methods

Following are the two basic IP address assignment strategies:

■ Static: An IP address is statically assigned to a system. The network administrator configures the IP address, default gateway, and name servers manually by entering them into a special file or files on the end system with either a graphical or text interface. Static address assignment is an extra burden for the administrator—especially on large-scale networks— who must configure the address on every end system in the network.

■ Dynamic: IP addresses are dynamically assigned to the end systems. Dynamic address assignment relieves the administrator of manually assigning an address to every network device. Instead, the administrator must set up a server to assign the addresses. On that server, the administrator defines the address pools and additional parameters that should be sent to the host (default gateway, name servers, time servers, and so forth). On the host, the administrator enables the host to acquire the address dynamically; this is often the default. When IP address reconfiguration is needed, the administrator reconfigures the server, which then performs the host-renumbering task. Examples of available address assignment protocols include Reverse Address Resolution Protocol, Boot Protocol, and DHCP. DHCP is the newest and provides the most features.

When to Use Static or Dynamic Address Assignment

To select either a static or dynamic end system IP address assignment method or a combination of

the two, consider the following:

■ Node type: Network devices such as routers and switches typically have static addresses. End-user devices such as PCs typically have dynamic addresses.

■ The number of end systems: If there are more than 30 end systems, dynamic address assignment is preferred. Static assignment can be used for smaller networks.

■ Renumbering: If renumbering is likely to happen and there are many end systems, dynamic address assignment is the best choice. With DHCP, only DHCP server reconfiguration is needed; with static assignment, all hosts must be reconfigured.

■ Address tracking: If the network policy requires address tracking, the static address assignment method might be easier to implement than the dynamic address assignment method. However, address tracking is also possible with dynamic address assignment with additional DHCP server configuration.

■ Additional parameters: DHCP is the easiest solution when additional parameters must be configured. The parameters have to be entered only on the DHCP server, which then sends the address and those parameters to the clients.

■ High availability: Statically assigned IP addresses are always available. Dynamically assigned IP addresses must be acquired from the server; if the server fails, the addresses cannot be acquired. To ensure reliability, a redundant DHCP server is required.

■ Security: With dynamic IP address assignment, anyone who connects to the network can acquire a valid IP address, in most cases. This might be a security risk. Static IP address assignment poses only a minor security risk.

The use of one address assignment method does not exclude the use of another in a different part of the network.

Guidelines for Assigning IP Addresses in the Enterprise Network

The typical enterprise network uses both static and dynamic address assignment methods. As shown in Figure 6-14, the static IP address assignment method is typically used for campus network infrastructure devices, in the Server Farm and Enterprise Data Center modules, and in the modules of the Enterprise Edge (the E-Commerce, Internet Connectivity, Remote Access and VPN, and WAN and MAN and Site-to-Site VPN modules). Static addresses are required for systems such as servers or network devices, in which the IP address must be known at all times for connectivity, general access, or management.

Figure 6-14 IP Address Assignment in an Enterprise Network

Enterprise Campus

Server Farm

Enterprise Edge

Continue reading here: Name Resolution

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• Configuring a Routed Port
• Hierarchical IP Address Design and Summarization
• Answers to the Chapter 6 QA Section
• IP Standard Access Lists - Network Design

Readers' Questions

How do know that your network is configured to assign an ip address to the thermostat?

To determine if your network is configured to assign an IP address to the thermostat, you can follow these steps: Check if your thermostat is connected to Wi-Fi: Ensure that your thermostat is successfully connected to your home Wi-Fi network. Most thermostats have an indicator light or display that shows the Wi-Fi connectivity status. Access your router's settings: Open a web browser on a device connected to the same network as your thermostat and enter your router's IP address (e.g., 192.168.1.1) in the address bar. Consult your router's user manual or contact your internet service provider for assistance if you don't know the router's IP address. Log in to your router's admin interface: Enter your router's admin username and password to log in to the router's settings page. If you haven't changed the login credentials, you may find the default ones on the router or in its manual. Locate the DHCP settings: DHCP (Dynamic Host Configuration Protocol) is responsible for assigning IP addresses to devices on your network. Find the DHCP settings page in your router's admin interface. It might be under a section like "LAN settings," "Network settings," "DHCP settings," or similar. Verify DHCP is enabled: Ensure that DHCP is enabled or turned on in your router's settings. This setting allows your router to assign IP addresses dynamically. Typically, DHCP is enabled by default. Check the assigned IP address table: Look for a section or tab in your router's settings that displays the list of devices connected to your network along with their assigned IP addresses. The table may be labeled as "Connected Devices," "Device list," "DHCP Client List," or alike. Ensure your thermostat appears in the list and has been assigned an IP address. If your thermostat appears in the assigned IP address table, it means your network is configured to assign an IP address to it. If it doesn't, you may need to troubleshoot the thermostat's Wi-Fi connection or contact the manufacturer's support for further assistance.

What protocol automatically configures ip configuration for a client?

The protocol that automatically configures IP configuration for a client is called DHCP (Dynamic Host Configuration Protocol). It allows clients to obtain IP addresses, subnet masks, default gateways, and other network configuration parameters automatically from a DHCP server. This eliminates the need for manual configuration of IP addresses on each client device.

Which protocol can configure a computer's ip address and subnet mask automatically?

The Dynamic Host Configuration Protocol (DHCP) is designed to automatically configure a computer's IP address and subnet mask. By using DHCP, a computer can obtain network configuration information including IP address, subnet mask, default gateway, and DNS server(s) without manual intervention.

When using fixed allocation dhcp, what is used to determine a computer's ip?

When using fixed allocation DHCP (Dynamic Host Configuration Protocol), the computer's Media Access Control (MAC) address is used to determine its IP (Internet Protocol) address. The DHCP server maintains a mapping between MAC addresses and IP addresses, known as a DHCP reservation. When a computer with a specific MAC address requests an IP address from the DHCP server, it checks if a reservation exists for that MAC address. If a reservation is found, the DHCP server assigns the corresponding IP address to the computer.

Which type of server dynamically assigns an ip address to a host?

A dynamic host configuration protocol (DHCP) server is responsible for assigning dynamic IP addresses to hosts on a network.

Which allocation method can be used with a dynamic host configuration?

The Dynamic Host Configuration Protocol (DHCP) typically uses the "Dynamic Allocation" method for allocating IP addresses to client devices. In this method, a pool of IP addresses is created, and the DHCP server selects an available address from that pool and assigns it to the requesting device. The address is leased to the device for a specific period, known as the lease duration. Once the lease expires, the address can be released back to the pool and assigned to another device. This allows for efficient and flexible allocation of IP addresses in dynamic network environments.

Which address should be configured as the default gateway address of a client device?

The default gateway address for a client device should be the IP address of the router or gateway that connects the client device to the network. This router or gateway is responsible for forwarding network traffic between the client device and other networks or the internet.

How to statically assign an ip address?

To statically assign an IP address, follow these steps: On your device, go to the network settings. This can usually be found in the control panel or system preferences. Look for the network adapter or connection that you want to configure and select it. Go to the properties or settings of the network adapter. Look for an option such as "Internet Protocol Version 4 (TCP/IPv4)" and select it. Click on the "Properties" button or double-click on the selected option. In the properties window, select the option to "Use the following IP address". Enter the desired IP address, subnet mask, default gateway, and DNS server addresses. Contact your network administrator or Internet Service Provider (ISP) for the appropriate values if you're unsure. Click on "OK" or "Apply" to save the changes. Please note that the steps to assign a static IP address may vary slightly depending on the operating system and device you are using.

Why is dhcp for ipv4 preferred for use on large networks?

There are several reasons why DHCP (Dynamic Host Configuration Protocol) for IPv4 is preferred for use on large networks: Efficient IP address management: Large networks typically have a large number of devices that need unique IP addresses. DHCP allows for automated IP address allocation, ensuring that each device connected to the network receives a unique IP address without manual configuration. This eliminates the need for manual IP address management, making it easier to handle IP address assignments on a large scale. Centralized control: DHCP allows for centralized management and control over IP address allocation. Network administrators can configure DHCP servers to provide specific IP address ranges, subnet masks, default gateways, and other network settings. This centralized control simplifies the network administration process and ensures consistency across the network. Scalability: DHCP is highly scalable, allowing for the dynamic allocation and re-allocation of IP addresses as devices join or leave the network. As new devices connect to the network, DHCP servers can quickly assign them IP addresses from the available pool. Similarly, when devices disconnect or are powered off, their IP addresses can be released back to the pool for subsequent allocation. Reduced configuration errors: Manual configuration of IP addresses on a large network can be error-prone, leading to network connectivity issues or IP address conflicts. With DHCP, the chances of configuration errors are minimized as the IP addresses are assigned automatically. This improves network reliability and reduces troubleshooting efforts. Network flexibility: Large networks often require network reconfiguration or changes, such as adding new subnets or modifying IP address ranges. DHCP simplifies these network changes by allowing administrators to modify the DHCP server configuration, rather than manually updating settings on each individual device. Overall, DHCP for IPv4 offers a more efficient, scalable, and reliable method of IP address allocation and management on large networks, thereby reducing administrative overhead and providing greater control over network resources.

How to assign ip address to a clents?

To assign an IP address to a client, you will need to follow these steps: Access your router's settings: In order to assign an IP address to a client, you need to be connected to the network router or have administrative access to its settings. Determine the client's MAC address: The Media Access Control (MAC) address is a unique identifier assigned to a network interface card (NIC) of a client. You can usually find the MAC address on the client's network settings or by using command prompts such as "ipconfig /all" (Windows) or "ifconfig" (Linux/Mac). Reserve an IP address in the router's settings: Access your router's settings interface (generally through a web browser by entering the router's IP address). Look for a section such as "DHCP Reservation" or "Address Reservation" and select it. Locate the option to add a new reservation and enter the client's MAC address along with the IP address you want to assign to it. Save and apply the changes: Once you have entered the necessary information, save the changes and apply them. This will ensure that the router reserves the assigned IP address for the client in the future. Restart the client device: To ensure the client receives the new assigned IP address, it is recommended to restart the client device. This will trigger it to request an IP address from the router, and if the reservation was successful, it will be assigned the specific IP address you specified. Note: The specific process may vary slightly depending on the router model and firmware version. Consult your router's manual or manufacturer's website for detailed instructions if needed.

What methods are used to assign tcp/ip parameters to network hosts (select two.)?

Dynamic Host Configuration Protocol (DHCP): DHCP is a network management protocol that automatically assigns IP addresses and other TCP/IP parameters to network hosts. It allows hosts to obtain necessary network configuration settings from a DHCP server dynamically. Manual Configuration: In this method, the TCP/IP parameters are manually assigned to network hosts by network administrators. This involves manually configuring the IP address, subnet mask, default gateway, and other parameters in the network host's settings. It requires manual input and configuration on each host individually.

Which network address and subnet mask does apipa use (select two.)?

-Network Address: 169.254.0.0 -Subnet Mask: 255.255.0.0

Which part of the network assigns an ip address?

The Dynamic Host Configuration Protocol (DHCP) assigns IP addresses to devices on a network.

Which organization is responsible for allocating public ip addresses?

The Internet Assigned Numbers Authority (IANA) is responsible for allocating public IP addresses. It is an organization that works under the supervision of the Internet Corporation for Assigned Names and Numbers (ICANN). IANA administers the global Internet Protocol address space and other Internet Protocol-related symbols and numbers.

Is responsible for the internet's domain name system and the allocation of ip addresses?

The Internet Corporation for Assigned Names and Numbers (ICANN) is responsible for the internet's domain name system and the allocation of IP addresses.

What is the name of the organization responsible for assigning public ip addresses?

The organization responsible for assigning public IP addresses is the Internet Assigned Numbers Authority (IANA).

How to change static ip address?

1. Open the Control Panel. 2. Go to Network and Internet > Network and Sharing Center. 3. Click the Change Adapter Settings link on the left-hand side. 4. Right-click on the active network adapter and select Properties. 5. Select the Internet Protocol Version 4 (TCP/IPv4) option and click the Properties button. 6. Select the Use the following IP address option and enter the static IP address, subnet mask, and default gateway. 7. Click Okay to save the settings.

What protocol is responsible for assigning ip addresses to hosts on most networks?

The Dynamic Host Configuration Protocol (DHCP) is responsible for assigning IP addresses to hosts on most networks.

Which protocol assigns ip address to the client connected in the internet?

The Dynamic Host Configuration Protocol (DHCP) is responsible for assigning IP addresses to clients who are connected to the Internet.

What are the types of ip address assignment?

Static IP address: This type of IP address assignment is a permanent address assigned to a device by an administrator. Dynamic IP address: This type of IP address assignment is a temporary address assigned to a device by a DHCP server. Private IP address: This type of IP address is used for internal networks and is typically assigned for the use of devices within a local network. Public IP address: This type of IP address is used for public networks and is assigned by an internet service provider (ISP).

Which protocol provides a way to automate the ip configuration?

Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers configured for a given network.

Which protocol assigns ip address to the client?

Dynamic Host Configuration Protocol (DHCP) is the protocol used to assign IP addresses to client devices.

Which two automatic addressing assignments are supported by dhcpv4 (choose two.)?

Dynamic Host Configuration Protocol (DHCP) Automatic Private IP Addressing (APIPA)

Which protocol should you use if you want to dynamically assign ip addresses to network clients?

The Dynamic Host Configuration Protocol (DHCP) should be used if you want to dynamically assign IP addresses to network clients.

What protocol is used to assign computers on a lan dynamic ip addresses?

Dynamic Host Configuration Protocol (DHCP)

How to manually assign ip address?

Open the Control Panel. Click on Network and Sharing Center. Choose Change adapter settings. Right click on the connection whose IP address you want to assign manually and select Properties. Select Internet Protocol Version 4 (TCP/IPv4). Click on the Properties button. Select the option "Use the following IP address". Enter the appropriate IP address and Subnet mask values. Enter the Default Gateway Address. Enter the Preferred and Alternate DNS server addresses. Click OK and then close out of all other open windows. Test your new settings.

How to assign ip address to devices?

Connect the device to the network. Use a DHCP server to assign an IP address to the device. Configure the device with a static IP address. Connect the device to a router and set the router to assign IP addresses to the device. Configure the device manually with a static IP address.

How to assign ip adress?

Open the Control Panel. Select "Network and Internet". Select "Network and Sharing Center". Select "Change adapter settings". Right-click on the network connection you want to change the IP address for and select "Properties". Select "Internet Protocol Version 4 (TCP/IPv4)". Select "Properties". Select "Use the following IP address". Enter the desired IP address. Enter the subnet mask. Enter the default gateway. Select "OK" to save the settings and close the window.

Why is dhcp preferred for use on large networks?

DHCP is preferred for use on large networks because it helps to automate the network configuration process. It eliminates the need for manual configuration of network settings. DHCP also helps reduce the risk of errors, by assigning the same IP address each time a computer connects to the network. It ensures that each client has its own unique IP address, allowing devices to communicate with each other. This increases the performance and reliability of the network.

Which two types of devices are typically assigned static ip addresses (choose two.)?

Servers Network Printers

How do you assign a server with an IP address?

To assign an IP address to a server, you will need to access the server's network settings in its operating system or hardware. From there, you can assign a static IP address or a dynamic one using DHCP.

What are the ways of assigning the Ip address?

There are several ways to assign an IP address to a device. Here are some common methods: Dynamic Host Configuration Protocol (DHCP): DHCP is commonly used in modern networks, where a central server automatically assigns IP addresses to devices on the network. The DHCP server manages a pool of available IP addresses and leases them to devices on request. Manual Configuration: This involves manually assigning a static IP address to a device. It is typically used for devices that require a consistent IP address, such as servers or network printers. The administrator manually enters the desired IP address, along with other network settings, directly into the device's network configuration. Zero-configuration Networking (Zeroconf): Zeroconf, also known as Automatic Private IP Addressing (APIPA), allows devices on a network to automatically assign IP addresses to themselves without a central server. It is commonly used in small home or office networks where there is no DHCP server available. Link-Local Addressing: Link-local addresses are IP addresses that are automatically assigned to devices on a local network segment without the need for a DHCP server. These addresses are typically used for network troubleshooting or communication within a small local network. Static IP Reservation: In some cases, network administrators may choose to use DHCP but reserve specific IP addresses for certain devices. This ensures that these devices always receive the same IP address each time they connect to the network. Dynamic DNS (DDNS): DDNS allows devices with dynamic IP addresses (addresses that change periodically) to be accessed by a hostname instead of the IP address. It involves using a service that updates the DNS records whenever the device's IP address changes. The method used to assign IP addresses depends on the network setup, device requirements, and network administrator's preferences.

Which method is used to assign ip address?

Dynamic Host Configuration Protocol (DHCP) is a network protocol used to assign IP addresses to devices on a network.

How to allocate ip address for network design?

Determine the IP address range to be allocated: Determine the total number of IP addresses needed and then calculate the appropriate IP address range based on the number of devices that need to be connected. Design the subnet mask: Design a subnet mask to divide the IP address range into subnets. Allocate the IP addresses: Allocate IP addresses to each device on the network based on their individual subnet masks. Configure the network devices: Configure the network devices with their assigned IP addresses and the appropriate subnet mask. Test the network: Test the network to ensure that all devices are assigned the correct IP addresses and the network is functioning properly.

How are IP adresses assigned to nodes in a network?

IP addresses are assigned to nodes in a network through DHCP (Dynamic Host Configuration Protocol). A DHCP server assigns a unique IP address to each node in a network from a pool of available IP addresses. The node then requests a lease from the DHCP server and stores the address for the duration of the lease.

When should a network administrator assign static IP addresses to network devices?

A network administrator should assign static IP addresses to network devices when the devices need to be accessed remotely and securely, or when the device needs to host services such as a web server, FTP server, or database. Static IP addresses are also useful for assigning devices to VLANs, managing traffic flow to and from the device, and configuring quality of service (QoS).

IP Subnet Calculator

This calculator returns a variety of information regarding Internet Protocol version 4 (IPv4) and IPv6 subnets including possible network addresses, usable host ranges, subnet mask, and IP class, among others.

IPv4 Subnet Calculator

Ipv6 subnet calculator.

Related Bandwidth Calculator | Binary Calculator

A subnet is a division of an IP network (internet protocol suite), where an IP network is a set of communications protocols used on the Internet and other similar networks. It is commonly known as TCP/IP (Transmission Control Protocol/Internet Protocol).

The act of dividing a network into at least two separate networks is called subnetting, and routers are devices that allow traffic exchange between subnetworks, serving as a physical boundary. IPv4 is the most common network addressing architecture used, though the use of IPv6 has been growing since 2006.

An IP address is comprised of a network number (routing prefix) and a rest field (host identifier). A rest field is an identifier that is specific to a given host or network interface. A routing prefix is often expressed using Classless Inter-Domain Routing (CIDR) notation for both IPv4 and IPv6. CIDR is a method used to create unique identifiers for networks, as well as individual devices. For IPv4, networks can also be characterized using a subnet mask, which is sometimes expressed in dot-decimal notation, as shown in the "Subnet" field in the calculator. All hosts on a subnetwork have the same network prefix, unlike the host identifier, which is a unique local identification. In IPv4, these subnet masks are used to differentiate the network number and host identifier. In IPv6, the network prefix performs a similar function as the subnet mask in IPv4, with the prefix length representing the number of bits in the address.

Prior to the introduction of CIDR, IPv4 network prefixes could be directly obtained from the IP address based on the class (A, B, or C, which vary based on the range of IP addresses they include) of the address and the network mask. Since the introduction of CIDRs, however, assigning an IP address to a network interface requires both an address and its network mask.

Below is a table providing typical subnets for IPv4.

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DHCP Secured IP Address Assignment

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The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

Table Of Contents DHCP Secured IP Address Assignment Contents Prerequisites for DHCP Secured IP Address Assignment Restrictions for DHCP Secured IP Address Assignment Information About DHCP Secured IP Address Assignment DHCP Operation in Public Wireless LANs Security Vulnerabilities in Public Wireless LANs ARP Entries and DHCP Bindings DHCP Secure IP Address Assignment Configuring Database Agents to Store DHCP Secured IP Addresses Configuring DHCP Accounting and DHCP Secured IP Address Assignment How to Configure DHCP Secured IP Address Assignment Securing ARP Table Entries to DHCP Leases Securing Insecure ARP Table Entries Troubleshooting Tips What to Do Next Verifying that ARP Table Entries Have Been Secured Securing Insecure ARP Table Entries Configuration Examples for DHCP Secured IP Address Assignment Securing an ARP Table Entry to an DHCP Lease Example Verifying Secured ARP Table Entries Example Where to Go Next Additional References Related Documents Standards MIBs RFCs Technical Assistance Command Reference update arp show ip dhcp server statistics DHCP Secured IP Address Assignment The DHCP Secure IP Address Assignment feature introduces the capability to secure ARP table entries to Dynamic Host Configuration Protocol (DHCP) leases in the DHCP database. This feature secures and synchronizes the MAC address of the client to the DHCP binding, preventing unauthorized clients or hackers from spoofing the DHCP server and taking over a DHCP lease of an authorized client. When this feature is enabled and the DHCP server assigns an IP address to the DHCP client, the DHCP server adds a secure ARP entry to the ARP table with the assigned IP address and the MAC address of the client. This ARP entry cannot be updated by any other dynamic ARP packets, and this ARP entry will exist in the ARP table for the configured lease time or as long as the lease is active. The secured ARP entry can be deleted only by an explicit termination message from the DHCP client or by the DHCP server when the DHCP binding expires. This feature can be configured for a new DHCP network or used to upgrade the security of an existing network. The configuration of this feature does not interrupt service and is not visible to the DHCP client. Feature Specifications for the DHCP Secured IP Address Assignment feature Feature History   Release Modification 12.2(15)T This feature was introduced. 12.2(27)SBA This feature was integrated into Cisco IOS Release 12.2(27)SBA. Finding Support Information for Platforms and Cisco IOS Software Images Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear. Contents • Prerequisites for DHCP Secured IP Address Assignment • Restrictions for DHCP Secured IP Address Assignment • Information About DHCP Secured IP Address Assignment • How to Configure DHCP Secured IP Address Assignment • Configuration Examples for DHCP Secured IP Address Assignment • Additional References • Command Reference Prerequisites for DHCP Secured IP Address Assignment This document assumes that your network is configured to run DHCP. You will also need to complete the following tasks before you can configure this feature: • Identify an external File Transport Protocol (FTP), Trivial File Transfer Protocol (TFTP), or remote copy protocol (rcp) server that you will use to store the DHCP bindings database. • Configure the pool of IP addresses that you will enable the DHCP server to assign and the IP addresses that you will exclude. Restrictions for DHCP Secured IP Address Assignment The following restrictions apply to the DHCP Secured IP Address Assignment feature: • This feature can only be configured for directly connected clients on LAN interfaces and wireless LAN interfaces. • When this feature is configured, client ARP entries that are created by a DHCP server cannot be removed from the ARP table by the clear arp-cache command. This is designed behavior. Information About DHCP Secured IP Address Assignment To configure this feature, you must understand the following concepts • DHCP Operation in Public Wireless LANs • Security Vulnerabilities in Public Wireless LANs • ARP Entries and DHCP Bindings • DHCP Secure IP Address Assignment • Configuring Database Agents to Store DHCP Secured IP Addresses • Configuring DHCP Accounting and DHCP Secured IP Address Assignment DHCP Operation in Public Wireless LANs The configuration of DHCP in a public wireless LAN (PWLAN) simplifies the configuration of wireless clients and reduces the overhead necessary to maintain the network. DHCP clients are leased IP addresses by the DHCP server and then authenticated by the Service Selection Gateway (SSG), which allows the clients to access network services. The DHCP server and client exchange DHCP messages for IP address assignments. When a DHCP server assigns an IP address to a client, a DHCP binding is created. The IP address is leased to the client until the client explicitly releases the IP address and disconnects from the network. When the client explicitly disconnects from the network, the DHCP lease is terminated by the DHCP server, and the IP address is returned to the DHCP pool. Security Vulnerabilities in Public Wireless LANs If the DHCP lease is not explicitly terminated by the client, the SSG will terminate the lease only when the ping-idle timer expires. This type of termination typically occurs in a PWLAN when an authenticated client moves out of range of the access point. This type of disconnection can expose a security vulnerability during the period of time it takes for the ping-idle timer to expire. By design, DHCP will maintain this lease if it receives an acknowledgement from the client. However, DHCP ARP table entries are dynamic and DHCP alone does not have the capability to secure the transmission and storage of the DHCP binding or verify the integrity of the information that is sent from the client. This exposes the PWLAN to the following security risks: • An unauthorized client or hacker can gain unauthorized access to the network. • The authorized client will be billed for cost-based services that the unauthorized client uses. A hacker can exploit this vulnerability by snooping for leases that have been dropped by the client but have not expired in the DHCP database. Once the hacker detects the unexpired lease, he or she can quickly reconfigure a laptop to use the unexpired lease. Because DHCP ARP entries are dynamic, a hacker can take control of the unexpired lease and access the network, posing as the authenticated client. ARP Entries and DHCP Bindings ARP table entries are dynamic by design. Request and reply ARP packets are sent and received by all the networking devices in a network. In a DHCP network, the DHCP server stores the leased IP address to the MAC address or the client-identifier of the client in the DHCP binding. But as ARP entries are learned dynamically, an unauthorized client can spoof the IP address given by the DHCP server and start using that IP address. The MAC address of this unauthorized client will replace the MAC address of the authorized client in the ARP table and this will allow the unauthorized client to freely use the spoofed IP address. DHCP Secure IP Address Assignment The DHCP Secure IP Address Assignment feature introduces the capability to add an ARP entry binding the MAC address of the client to the DHCP offered IP address. The ARP table entry and DHCP binding can only be deleted by the DHCP server when a DHCP lease expires or is terminated by the client. The ARP table entry will not be overwritten if the DHCP server receives any unsolicited ARP request messages. When the DHCP lease expires or the client terminates the lease, the DHCP server will destroy the DHCP binding and the leased IP address is returned to the DHCP address pool. The secure ARP entry will be removed from the ARP table. Note This feature does not secure ARP table entries for BOOTP clients. When the DHCP Secured IP Address feature is enabled, the ARP table entries and corresponding DHCP leases are secured automatically for all new leases and DHCP bindings. However, existing active leases are not secured. These leases are still insecure until they are renewed. When the lease is renewed, it is treated as a new lease and will be secured automatically. If this feature is disabled on the DHCP server, all existing secured ARP table entries will automatically change to dynamic ARP entries. Configuring Database Agents to Store DHCP Secured IP Addresses The DHCP Secured IP Address feature also supports the configuration of DHCP database agents. Database agents are used to configure an IOS DHCP server to store DHCP binding information for recovery after a router is reloaded. When this feature is enabled, secure ARP table entries can also be saved to a file, like DHCP bindings, by a DHCP database agent for recovery. These files are transferred using the File Transfer Protocol (FTP), Trivial File Transport Protocol (TFTP), or remote copy protocol (rcp). If a DHCP database agent is configured, the secured lease information is saved in a remote file system. See the following sample output: !IP address Type Hardware address Interface-index arp 10.0.0.1    1    0060.837b.964c   0 0 The "arp" keyword that precedes the IP address indicates that the secure ARP entry will be saved before the router reloads. When a router is reloaded, the DHCP bindings are added to the DHCP database and secured ARP entries are added to the ARP table. The ip dhcp database command is used to configure a database agent on an IOS DHCP server. The database agent will automatically store secure ARP table entries when this feature is configured. No new task are introduced by this feature. For more information about configuring database agents, refer to the "Configuring DHCP" chapter of the Cisco IOS IP Configuration Guide , Release 12.2: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt1/1cfdhcp.htm Configuring DHCP Accounting and DHCP Secured IP Address Assignment For an additional layer of security, the DHCP Accounting feature can be configured with the DHCP Secured IP Address Assignment feature. The DHCP Accounting feature introduces authentication, authorization, and accounting (AAA) and Remote Authentication Dial-In User Service (RADIUS) support for DHCP configuration. The introduction of AAA and RADIUS support improves PWLAN security by sending secure START and STOP accounting messages. The configuration of this feature adds a layer of security to prevent unauthorized clients or hackers from gaining illegal entry to the network by spoofing authorized DHCP leases. The configuration of these two features greatly improves the security of DHCP operation and can be used to protect PWLANs by preventing unauthorized clients or hackers from gaining illegal entry to the network by spoofing authorized DHCP leases. For more information about the DHCP Accounting feature, see the following document: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122limit/122t/122t15/ftdhcpac.htm How to Configure DHCP Secured IP Address Assignment This section contains the following procedures for configuring the DHCP Secured IP Address Assignment feature: • Securing ARP Table Entries to DHCP Leases • Verifying that ARP Table Entries Have Been Secured Securing ARP Table Entries to DHCP Leases Use the following steps to enable the DHCP Secured IP Address Assignment feature: Securing Insecure ARP Table Entries When the DHCP Secured IP Address feature is enabled, ARP table entries and their corresponding DHCP leases are secured automatically for all new leases and DHCP bindings. However, existing active leases are not secured. These leases are still insecure until they are renewed. When the lease is renewed, it is treated as a new lease and will be secured automatically. If this feature is disabled on the DHCP server, all existing secured ARP table entries will automatically change to dynamic ARP entries. SUMMARY STEPS 1. enable 2. configure { terminal | memory | network } 3. ip dhcp pool pool-name 4. update arp 5. exit DETAILED STEPS   Command or Action Purpose Step 1  enable Example: Router> enable Enables higher privilege levels, such as privileged EXEC mode. • Enter your password if prompted. Step 2  configure { terminal | memory | network } Example: Router# configure terminal Enters global configuration mode. Step 3  ip dhcp pool pool-name Example: Router(config)# ip dhcp pool WIRELESS-POOL Configures a DHCP address pool and enters DHCP pool configuration mode. Step 4  update arp Example: Router(dhcp-config)# update arp Secures insecure ARP table entries to the corresponding DHCP leases. Existing active DHCP leases will not be secured until they are renewed. Issuing the no update arp command will change secured ARP table entries back to dynamic ARP table entries. Step 5  Exit Example: Router(dhcp-config)# exit Exits DHCP pool configuration mode and enters global configuration mode. Troubleshooting Tips The clear ip dhcp binding command can be used to clear DHCP bindings and secured ARP table entries. What to Do Next The DHCP Accounting feature can be configured to provide an additional layer of security. When this feature is configured, the SSG will use secure START and STOP accounting messages to control DHCP lease assignment and termination. For more information about the DHCP Accounting feature, refer to the following document: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122limit/122t/122t15/ftdhcpac.htm The ip dhcp database command can be used to configure a database agent on an IOS DHCP server. The database agent will automatically store secure ARP table entries when this feature is configured. No new task are introduced by this feature. For more information about configuring database agents, refer to the "Configuring DHCP" chapter of the Cisco IOS IP Configuration Guide , Release 12.2: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt1/1cfdhcp.htm Verifying that ARP Table Entries Have Been Secured Use the following steps to verify that ARP table entries have been secured to their corresponding DHCP leases: Securing Insecure ARP Table Entries The show ip dhcp server statistics command has been enhanced for this feature to show how many secure ARP entries have been added by the DHCP server. SUMMARY STEPS 1. enable 2. show ip dhcp server statistics DETAILED STEPS   Command or Action Purpose Step 1  enable Example: Router> enable Enables higher privilege levels, such as privileged EXEC mode. • Enter your password if prompted. Step 2  show ip dhcp server statistics Example: Router# show ip server statistics Displays Cisco IOS Dynamic Host Configuration Protocol (DHCP) Server statistics, including secured ARP table entries. Configuration Examples for DHCP Secured IP Address Assignment • Securing an ARP Table Entry to an DHCP Lease Example • Verifying Secured ARP Table Entries Example Securing an ARP Table Entry to an DHCP Lease Example The following example configures the Cisco IOS DHCP server to secure ARP table entries to their corresponding DHCP leases within the DHCP pool named WIRELESS-POOL: Router(config)# ip dhcp pool WIRELESS-POOL Router(dhcp-config)# update arp Router(dhcp-config)# exit Note Existing active leases are not secured until they are renewed. When the lease is renewed, it is treated as a new lease and will be secured automatically. If the no update arp command is issued, all existing secured ARP table entries will automatically be changed to dynamic ARP entries. Verifying Secured ARP Table Entries Example To verify that the ARP table entries have been secured to their corresponding DHCP leases, use the show ip dhcp server statistics command. The output from this command displays the number of secure ARP table entries on the last line in the first section of the output. The following output shows that 1 secured ARP table entry exists: Router#  show ip dhcp server statistics Memory usage 13745 Address pools 1 Database agents 0 Automatic bindings 1 Manual bindings 0 Expired bindings 0 Malformed messages 0 Secure arp entries 1 Message Received BOOTREQUEST 2 DHCPDISCOVER 2 DHCPREQUEST 2 DHCPDECLINE 0 DHCPRELEASE 1 DHCPINFORM 0 Message Sent BOOTREPLY 0 DHCPOFFER 0 DHCPACK 2 DHCPNAK 0 Where to Go Next For information about configuring the DHCP Accounting feature, refer to the following document: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t15/ftdhcpac.htm Additional References For additional information related to DHCP Secured IP Address Assignment, refer to the following references: Related Documents Related Topic Document Title DHCP commands Cisco IOS IP Command Reference, Volume1 of 3: Addressing and Services , Release 12.2 DHCP configuration tasks, including the configuration of DHCP database agents Cisco IOS IP Configuration Guide , Release 12.2 DHCP accounting for the transmission of secure START and STOP messages. DHCP Accounting , Release 12.2(15)T http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t15/ftdhcpac.htm Standards Standards 1 Title No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. — 1 Not all supported standards are listed. MIBs MIBs 1 MIBs Link No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml 1 Not all supported MIBs are listed. To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://tools.cisco.com/ITDIT/MIBS/servlet/index If Cisco  MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco  MIBs page at the following URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to [email protected]. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL: http://www.cisco.com/register RFCs RFCs 1 Title RFC 2131 Dynamic Host Configuration Protocol RFC 2132 DHCP Options and BOOTP Vendor Extensions 1 Not all supported RFCs are listed. Technical Assistance Description Link Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, tools, and lots more. Registered Cisco.com users can log in from this page to access even more content. http://www.cisco.com/public/support/tac/home.shtml Command Reference This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications. New Commands • update arp Modified Commands • show ip dhcp server statistics update arp To secure dynamic Address Resolution Protocol (ARP) entries in the ARP table to their corresponding DHCP bindings, use the update arp command in DHCP pool configuration mode. To disable this command and change secure ARP entries to dynamic ARP entries, use the no form of this command. update arp no update arp Syntax Description This command has no keywords or arguments. Defaults No default behavior or values. Command Modes DHCP pool configuration Command History Release Modification 12.2(15)T This command was introduced. 12.2(27)SBA This command was integrated into Cisco IOS Release 12.2(27)SBA. Usage Guidelines The update arp DHCP pool configuration command is used to secure ARP table entries and their corresponding DHCP leases. However, existing active leases are not secured. These leases will remain insecure until they are renewed. When the lease is renewed, it is treated as a new lease and will be secured automatically. If this feature is disabled on the DHCP server, all existing secured ARP table entries will automatically change to dynamic ARP entries. This command can be configured only under the following conditions: • DHCP network pools in which bindings are created automatically and destroyed upon lease termination or when the client sends a DHCPRELEASE message. • Directly connected clients on LAN interfaces and wireless LAN interfaces. The configuration of this command is not visible to the client. When this command is configured, secured ARP table entries that are created by a DHCP server cannot be removed from the ARP table by the clear arp-cache command. This is designed behavior. If a secure ARP entry created by the DHCP server must be removed, the clear ip dhcp binding command can be used. This command will clear the DHCP binding and secured ARP table entry. Note This command does not secure ARP table entries for BOOTP clients. Examples The following example configures the Cisco IOS DHCP server to secure ARP table entries to their corresponding DHCP leases within the DHCP pool named WIRELESS-POOL: Router(config)#  ip dhcp pool WIRELESS-POOL Router(dhcp-config)#  update arp Router(dhcp-config)#  exit Related Commands Command Description accounting (DHCP) Enables DHCP accounting for the specified server group. aaa accounting Enables AAA accounting of requested services for billing or security purposes when you use RADIUS or TACACS+. aaa group server Groups different server hosts into distinct lists and distinct methods. aaa new-model Enables the AAA access control model. aaa session-id Specifies whether the same session ID will be used for each AAA accounting service type within a call or whether a different session ID will be assigned to each accounting service type. clear arp-cache Deletes all dynamic entries from the ARP cache. clear ip dhcp binding Deletes an automatic address binding from the Cisco IOS DHCP Server database. ip dhcp database Configures a Cisco IOS DHCP Server to save automatic bindings on a remote host called a database agent. ip dhcp pool Configures a DHCP address pool on a Cisco IOS DHCP Server and enters DHCP pool configuration mode. ip radius source-interface Forces RADIUS to use the IP address of a specified interface for all outgoing RADIUS packets. radius-server host Specifies a RADIUS server host. radius-server retransmit Specifies the number of times that Cisco IOS will look for RADIUS server hosts. show ip dhcp binding Displays address bindings on the Cisco IOS DHCP server. show ip dhcp server statistics Displays Cisco IOS DHCP server statistics. show ip dhcp server statistics To display Cisco IOS Dynamic Host Configuration Protocol (DHCP) server statistics, use the show ip dhcp server statistics command in privileged EXEC mode. show ip dhcp server statistics Syntax Description This command has no arguments or keywords. Command Modes Privileged EXEC Command History Release Modification 12.0(1)T This command was introduced. 12.2(27)SBA This command was integrated into Cisco IOS Release 12.2(27)SBA. Examples The following example displays DHCP server statistics. Table 1 lists descriptions for each field in the example. Router> show ip dhcp server statistics Memory usage          40392 Address pools         3 Database agents       1 Automatic bindings    190 Manual bindings       1 Expired bindings      3 Malformed messages    0 Secure arp entries    1 Message               Received BOOTREQUEST           12 DHCPDISCOVER          200 DHCPREQUEST           178 DHCPDECLINE           0 DHCPRELEASE           0 DHCPINFORM            0 Message               Sent BOOTREPLY             12 DHCPOFFER             190 DHCPACK               172 DHCPNAK               6 Table 1 show ip dhcp server statistics Field Descriptions  Field Description Memory usage The number of bytes of RAM allocated by the DHCP server. Address pools The number of configured address pools in the DHCP database. Database agents The number of database agents configured in the DHCP database. Automatic bindings The number of IP addresses that have been automatically mapped to the MAC addresses of hosts that are found in the DHCP database. Manual bindings The number of IP addresses that have been manually mapped to the MAC addresses of hosts that are found in the DHCP database. Expired bindings The number of expired leases. Malformed messages The number of truncated or corrupted messages that were received by the DHCP server. Secure arp entries The number of ARP entries that heve been secured to the MAC address of the client interface. Message The DHCP message type that was received by the DHCP server. Received The number of DHCP messages that were received by the DHCP server. Sent The number of DHCP messages that were sent by the DHCP server. Related Commands Command Description clear ip dhcp server statistics Resets all Cisco IOS DHCP server counters. Copyright © 2003-2005 Cisco Systems, Inc. All rights reserved.

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How-To Geek

How to assign a static ip address in windows 10 or windows 11.

When organizing your home network it's easier to assign each computer it's own IP address than using DHCP. Here we will take a look at doing it in XP,

Quick Links

What is a static ip address, assign static ip addresses via your router, how to set a static ip address in windows 11, how to set a static ip address in windows 10, how to set a static ip address in windows 7 or 8 using "network connections", set a static ip address in windows vista, set a static ip address in windows xp, key takeaways.

• To set a static IP address in Windows 10 or 11, open Settings -> Network & Internet and click Properties for your active network.
• Choose the "Edit" button next to IP assignment and change the type to Manual.
• Flip the IPv4 switch to "On", fill out your static IP details, and click Save.

Sometimes, it's better to assign a PC its own IP address rather than letting your router assign one automatically. Join us as we take a look at assigning a static IP address in Windows.

A static IP address is manually set to a permanent, fixed address rather than being assigned automatically by your router using a procotol known as Dynamic Host Configuration Protocol (DHCP). DHCP is a handy way for devices to connect to your network more easily, because you don't have to configure IP addressing for each new device yourself. The downside to automatic addressing is that it's possible for a device's IP address to change from time to time, which is why people choose static IPs for certain types of devices. For example:

• You have a device like a home media server that you want to be able to find using the same IP address or host name each time.
• You have certain apps that can only connect to network devices using their IP address. In particular, many older networking apps suffer this limitation.
• You forward ports through your router to devices on your network. Some routers play nice with port forwarding and dynamic IP addresses; others do not.

Whatever your reason, assigning static IP addresses to devices is not difficult, but you do have a choice to make---whether to do it from the router or on the device itself.

Related: How to Set a Static IP Address in Ubuntu

While this article covers assigning static IP addresses to PCs within Windows itself, there is another way to go about it. Many routers allow you to assign a pool of IP addresses that are handed out to specific devices (based on the device's physical, or MAC address). This method offers a couple of significant advantages:

• IP addresses are still managed by the router, meaning that you won't have to make (and keep up with) changes on each individual device.
• It's easier to assign addresses within the same IP address pool your router uses.

This article is about assigning static IP addresses directly to PCs running Windows. We've already got a great guide on How to Set Static IP Addresses On Your Router , so if that's the way you want to go, be sure to give it a read.

With all that in mind, though, let's take a look at how to assign static IP addresses within any version of Windows.

Related: How to Find Your Router's IP Address on Any Computer, Smartphone, or Tablet

To set a static IP address in Windows 11, you'll want to open Settings, go to Network & Internet, and then find the Properties for your network. Inside there you'll be able to click the Edit button for IP Assignment and then fill out the manual network details.

First, open up the Settings app and then find Network & Internet on the left-hand side. You'll be presented with a panel that shows your current network connection. You can click where it says "Properties" right underneath the network, or if you have multiple network connections you can drill down into the specific network to see the IP address details for each one . In this case it's called "Ethernet", but you will most likely see "Wi-Fi" as the option to choose.

Once you've drilled down into the network connection that you want to set a manual IP for, scroll down until you see "IP Assignment" and then click the Edit button to the right.

Once there, you'll flip the drop-down to "Manual" and switch the IPv4 switch to "On". At this point you can fill out your network details and click Save to finish.

You can also use the old-school Network Connections panel in Windows 11, so if you prefer to use that method, keep reading.

If you're interested in more advanced networking, you might need to set up a static TCP/IP route , reset the entire TCP/IP stack on Windows , check open TCP/IP ports , find your MAC address on Windows , or find your IP address from the Command Prompt . We've got you covered there too.

To set a static IP address in Windows 10, you'll need to open the Settings app and drill down to Network & Internet. From there you'll select Properties for your network, and then the Edit button next to IP Assignment where you can input a manual IP address.

First, open the Settings app and locate the Network & Internet button.

On the next screen you'll see your network status, which should show you your active network. Here you'll want to click the Properties button. If you have multiple different networks, you could select them from the left-hand menu---in our case you'll notice we have both Wi-Fi and Ethernet networks, so you'll want to pick the one that you are trying to set a manual IP address for. You'll notice this is the same method we use when we're trying to find an IP address on Windows 10 .

On the network properties screen, scroll down until you see "IP settings" and click the Edit button under "IP assignment".

In the resulting popup window, change the Edit IP settings dropdown to Manual and then flip the IPv4 switch to "On". Fill out the details, click Save, and you should be good to go.

You might need to reboot to get all of your applications to work properly, just because it's Windows.

It's worth noting that you can use the old Network Connections method to set an IP address in any version of Windows, so if you prefer that method, keep reading.

To change the computer's IP address in Windows 7, you'll need to open the "Network Connections" window. Hit Windows+R, type "ncpa.cpl" into the Run box, and then hit Enter.

In the "Network Connections" window, right-click the adapter for which you want to set a static IP address, and then select the "Properties" command.

In the properties window for the adapter, select "Internet Protocol Version 4 (TCP/IPv4)" and then click the "Properties" button.

Select the "Use the following IP address" option, and then type in the IP address, subnet mask, and default gateway that corresponds with your network setup. Next, type in your preferred and alternate DNS server addresses. Finally, select the "Validate settings upon exit" option so that Windows immediately checks your new IP address and corresponding information to ensure that it works. When you're ready, click the "OK" button.

And then close out of the network adapter's properties window.

Windows automatically runs network diagnostics to verify that the connection is good. If there are problems, Windows will give you the option of running the Network troubleshooting wizard. However, if you do run into trouble, the wizard likely won't do you too much good. It's better to check that your settings are valid and try again.

Changing your IP from DHCP to a Static address in Vista is similar to other versions of Windows, but getting to the correct location is a bit different. Open the Start Menu, right-click on Network, and select Properties.

The Network and Sharing Center opens...click on Manage network connections.

Right-click on the network adapter you want to assign an IP address and click Properties.

Highlight Internet Protocol Version 4 (TCP/IPv4) then click the Properties button.

Now change the IP, Subnet mask, Default Gateway, and DNS Server Addresses. When you're finished click OK.

You'll need to close out of Local Area Connection Properties for the settings to go into effect.

Open the Command Prompt and use the

command to verify that the changes were successful.

To set a Static IP in Windows XP, right-click the "My Network Places" icon, and then select "Properties."

Right-click the adapter for which you want to set the IP, and then select "Properties" from the context menu.

Select the "Internet Protocol (TCP/IP)" entry, and then click the "Properties" button.

Select the "Use the following IP address" option. Type in the IP address, subnet mask, default gateway, and DNS server addresses you want to use. When you're finished, click the "OK" button.

You will need to close out of the adapter's properties window before the changes go into effect.

And you can verify your new settings by using the

 command at the command prompt.

By and large, it's better to let most of your devices have their IP addresses assigned automatically by your router. Occasionally, though, you might want to set a static IP address for a particular device. While you can set static IP addresses directly on your devices (and this article has shown you how to do just that on Windows PCs), we still recommending setting up static IP addressing on your router if possible. It will just make life easier.

Related: How to Find Any Device's IP Address, MAC Address, and Other Network Connection Details

IP address management strategy

Before configuring a PPP connection profile, you should be familiar with your network IP address management strategy. This strategy influences many of the decisions throughout the configuration process including your authentication strategies, security considerations, and TCP/IP settings.

Starting in IBM® i 7.1, PPP can support both IPv4 and IPv6 addresses. A PPP connection profile can have only IPv4 enabled, only IPv6 enabled, or both IPv4 and IPv6 enabled. By default, both IPv4 and IPv6 are enabled for a PPP connection profile.

IPv4 Address Management

The IP Control Protocol (IPCP) is used to configure and enable IPv4 on both ends of a PPP link. Options related to IPCP and IPv4 address assignment are located on the TCP/IP IPv4 Settings section of a connection profile.

Originator connection profiles

Typically, the local and remote IPv4 addresses defined for an originator profile will be defined as Assigned by remote system . This enables the administrators on the remote system to have control over the IP addresses that will be used for the connection. Most all connections to Internet service providers (ISP) will be defined this way, although many ISPs can offer fixed IP addresses for an additional fee.

If you define fixed IP addresses for either the local or remote IP address, you must be sure that the remote system is defined to accept the IP addresses you have defined. One typical application is to define your local IP address as a fixed IP address and the remote to be assigned by the remote system. The system you are connecting can be defined the same way so when you connect, the two systems will exchange IP addresses with each other as a way to learn the IP address of the remote system. This might be useful for one office calling another office for temporary connectivity.

Another consideration is whether you want to enable IP address masquerading. For example, if the system connects to the Internet through an ISP, this can allow an attached network behind the system to access the Internet. Basically, the system hides the IP addresses of the systems on the network behind the local IP address assigned by the ISP, thus making all IP traffic appear to be from the system. There are also additional routing considerations for both the systems on the LAN (to ensure their Internet traffic is sent to the system) as well as the system where you need to enable the add remote system as the default route box.

Receiver connection profiles

Receiver connection profiles have many more IPv4 address considerations and options than the Originator Connection Profile does. How you configure the IP addresses depends on the IP address management plan for your network, your specific performance and functional requirements for this connection, and the security plan.

Local IP addresses

For a single receiver profile, you can define a unique IP address or use an existing local IP address on your system to identify the end of the PPP connection. For receiver profiles defined to support multiple connections at the same time, you must use an existing local IP address. If no existing local IP addresses are present, you can create a virtual IP address for this purpose.

Remote IP addresses

There are many options for assigning remote IP addresses to PPP clients. The following options can be specified on the TCP/IP page of the receiver connection profile.

IPv6 Address Management

The IPv6 Control Protocol (IPV6CP) is used to configure and enable IPv6 on both ends of a PPP link. Options related to IPV6CP and IPv6 address assignment are located on the TCP/IP IPv6 Settings section of a connection profile.

IPv6 address assignment on a PPP link differs from IPv4 since only a 64-bit interface identifier is negotiated during PPP link establishment. Stateless address autoconfiguration is then used to automatically configure IPv6 addresses for the PPP link. The IPv6 addresses are created by combining an address prefix with the PPP link's interface identifier. A link-local IPv6 address is always created for the PPP link by combining the link-local address prefix (fe80::/10) with the PPP link's interface identifier. Additional IPv6 addresses can be generated by combining a 64-bit network prefix received in a Router Advertisement message with the PPP link's interface identifier. Additional IPv6 addresses can also be assigned to the PPP link using Dynamic Host Configuration Protocol (DHCPv6).

The IBM i TCP/IP stack implements Neighbor Discovery over PPP links in order to support stateless address autoconfiguration. There are two different scenarios for Neighbor Discovery on a PPP link.

In the first scenario, the PPP connection profile has IPv6 datagram forwarding enabled and is the server side of the link. Router Advertisement messages containing information such as a 64-bit address prefix, whether the router is a default router, and the availability of DHCPv6 services are sent over the PPP link. The client side of the link can use this information to configure IPv6 addresses.

In the second scenario, the PPP connection profile does not have IPv6 datagram forwarding enabled and is the client side of the link. Router Solicit messages are sent out over the PPP link and information from Router Advertisement messages received in response are used to configure IPv6 addresses.

IBM i cannot be both the client and the server side of the link at the same time.

In the IPv4 IP address space, there are five classes: A, B, C, D and E. Each class has a specific range of IP addresses (and ultimately dictates the number of devices you can have on your network). Primarily, class A, B, and C are used by the majority of devices on the Internet. Class D and class E are for special uses.

The list below shows the five available IP classes, along with the number of networks each can support and the maximum number of hosts (devices) that can be on each of those networks. The four octets that make up an IP address are conventionally represented by a.b.c.d - such as 127.10.20.30.

Additionally, information is also provided on private addresses and loop address (used for network troubleshooting).

Class A Public & Private IP Address Range

Class A addresses are for networks with large number of total hosts. Class A allows for 126 networks by using the first octet for the network ID. The first bit in this octet, is always zero. The remaining seven bits in this octet complete the network ID. The 24 bits in the remaining three octets represent the hosts ID and allows for approximately 17 million hosts per network. Class A network number values begin at 1 and end at 127.

• First octet value range from 1 to 127
• Private IP Range: 10.0.0.0 to 10.255.255.255 (See Private IP Addresses below for more information)
• Subnet Mask: 255.0.0.0 (8 bits)
• Number of Networks: 126
• Number of Hosts per Network: 16,777,214

Class B Public & Private IP Address Range

Class B addresses are for medium to large sized networks. Class B allows for 16,384 networks by using the first two octets for the network ID. The first two bits in the first octet are always 1 0. The remaining six bits, together with the second octet, complete the network ID. The 16 bits in the third and fourth octet represent host ID and allows for approximately 65,000 hosts per network. Class B network number values begin at 128 and end at 191.

• First octet value range from 128 to 191
• Private IP Range: 172.16.0.0 to 172.31.255.255 (See Private IP Addresses below for more information)
• Subnet Mask: 255.255.0.0 (16 bits)
• Number of Networks: 16,382
• Number of Hosts per Network: 65,534

Class C Public & Private IP Address Range

Class C addresses are used in small local area networks (LANs). Class C allows for approximately 2 million networks by using the first three octets for the network ID. In a class C IP address, the first three bits of the first octet are always 1 1 0. And the remaining 21 bits of first three octets complete the network ID. The last octet (8 bits) represent the host ID and allows for 254 hosts per network. Class C network number values begins at 192 and end at 223.

• First octet value range from 192 to 223
• Private IP Range: 192.168.0.0 to 192.168.255.255 (See Private IP Addresses below for more information)
• Special IP Range: 127.0.0.1 to 127.255.255.255 (See Special IP Addresses below for more information)
• Subnet Mask: 255.255.255.0 (24 bits)
• Number of Networks: 2,097,150
• Number of Hosts per Network: 254

Class D IP Address Range

Class D IP addresses are not allocated to hosts and are used for multicasting. Multicasting allows a single host to send a single stream of data to thousands of hosts across the Internet at the same time. It is often used for audio and video streaming, such as IP-based cable TV networks. Another example is the delivery of real-time stock market data from one source to many brokerage companies.

• First octet value range from 224 to 239
• Number of Networks: N/A
• Number of Hosts per Network: Multicasting

Class E IP Address Class

Class E IP addresses are not allocated to hosts and are not available for general use. These are reserved for research purposes.

• First octet value range from 240 to 255
• Number of Hosts per Network: Research/Reserved/Experimental

Private IP Addresses

Within each network class, there are designated IP address that is reserved specifically for private/internal use only. This IP address cannot be used on Internet-facing devices as that are non-routable. For example, web servers and FTP servers must use non-private IP addresses. However, within your own home or business network, private IP addresses are assigned to your devices (such as workstations, printers, and file servers).

• Class A Private Range: 10.0.0.0 to 10.255.255.255
• Automatic Private IP Addressing (APIPA) is a feature with Microsoft Windows -based computers to automatically assign itself an IP address within this range if a Dynamic Host Configuration Protocol (DHCP) server is not available on the network. A DHCP server is a network device that is responsible for assigning IP addresses to devices on the network. At your home, your Internet modem or router likely provides this functionality. In your work place, a Microsoft Windows Server , a network firewall, or some other specialized network device likely provides this functionality for the computer at your work environment.
• Class B Private Range: 172.16.0.0 to 172.31.255.255
• Class C Private Range: 192.168.0.0 to 192.168.255.255

Special IP Addresses

• IP Range: 127.0.0.1 to 127.255.255.255 are network testing addresses (also referred to as loop-back addresses). These are virtual IP address, in that they cannot be assigned to a device. Specifically, the IP 127.0.0.1 is often used to troubleshoot network connectivity issues using the ping command . Specifically, it tests a computer's TCP/IP network software driver to ensure it is working properly. Learn how to use ping 127.0.0.1 to test your computer's TCP/IP network stack.

Summary of IPv4 Classes

Best IP training I have ever seen for IPv4 addressing ...

Tips and tricks to use sub-netting!