Planning Your TCP/IP Network (Task)

This chapter describes the issues you must resolve in order to create your network in an organized, cost-effective manner. After you resolve these issues, you can devise a plan for your network to follow as you configure and administer your network in the future.

This chapter contains the following information:

• Designing the Network

• Setting Up an IP Address Scheme

• Naming Entities on Your Network

• Registering Your Network

• Adding Routers

Designing the Network

When you design your network, you must decide what type of network best meets the needs of your organization. Some of the planning decisions you make involve the following network hardware:

• Number of host machines your network can support

• Type of network media to use: Ethernet, token ring, FDDI, and so on

• Network topology, the layout and connections of the network hardware

• Types of hosts the network supports: standalone and dataless

Based on these factors, you can determine the size of your local area network.

Note - How you plan the network hardware is outside the scope of this manual. For assistance, refer to the manuals that come with your hardware.

Network Planning Tasks

After you complete your hardware plan, you are ready to begin network planning, from the software perspective.

As part of the planning process, you must do the following:

1. Obtain a network number and, if applicable, register your network domain with the InterNIC.

2. Devise an IP addressing scheme for your hosts, after you receive your IP network number.

3. Create a list that contains the IP addresses and host names of all machines on your network. Use the list to build network databases.

4. Determine which name service to use on your network: NIS, NIS+, DNS, or the network databases in the local /etc directory.

5. Establish administrative subdivisions, if appropriate for your network.

6. Determine if your network is large enough to require routers, and, if appropriate, create a network topology that supports them.

7. Set up subnets, if appropriate, for your network.

The remainder of this chapter explains how to plan your network.

Setting Up an IP Address Scheme

The number of machines that you expect to support affects how you configure your network. Your organization might require a small network of several dozen standalone machines that are located on one floor of a single building. Alternatively, you might need to set up a network with more than 1000 hosts in several buildings. This arrangement can require you to further divide your network into subdivisions that are called subnets. The size of your prospective network affects the following factors:

• Network class that you apply for

• Network number that you receive

• IP addressing scheme that you use for your network

Administering Network Numbers

If your organization has been assigned more than one network number, or uses subnets, appoint a centralized authority within your organization to assign network numbers. That authority should maintain control of a pool of assigned network numbers, and assign network, subnet, and host numbers as required. To prevent problems, ensure that duplicate or random network numbers do not exist in your organization. If you are planning to transition to IPv6, see Chapter 17, Transitioning From IPv4 to IPv6 (Reference).

Designing Your IPv4 Addressing Scheme

After you receive your network number, you can then plan how to assign the host parts of the IPv4 address.

The following table shows the division of the IPv4 address space into network and host address spaces. For each class, "Range" specifies the range of decimal values for the first byte of the network number. "Network Address" indicates the number of bytes of the IPv4 address that are dedicated to the network part of the address. Each byte is represented by xxx. "Host Address" indicates the number of bytes that are dedicated to the host part of the address. For example, in a class A network address, the first byte is dedicated to the network, and the last three bytes are dedicated to the host. The opposite designation is true for a class C network.

Table 3-1 Division of IPv4 Address Space

The numbers in the first byte of the IPv4 address define whether the network is class A, B, or C. InterNIC assigns the numbers. The remaining three bytes have a range from 0-255. The numbers 0 and 255 are reserved. You can assign the numbers 1-254 to each byte, depending on the network number that is assigned to you.

The following table shows which bytes of the IPv4 address are assigned to you. The following table also shows the range of numbers within each byte that are available for you to assign to your hosts.

Table 3-2 Range of Available Numbers