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Planning an IPv4 Addressing Scheme (Tasks
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 network plan as you configure and administer your network in the future.
This chapter contains the following information:
For tasks for configuring a network, refer to Chapter 5, Configuring TCP/IP Network Services and IPv4 Addressing (Tasks).
Network Planning (Task Map)
Task | Description | For Information |
|---|---|---|
1. Plan your hardware requirements and network topology | Determine the types of equipment that you need and the layout of this equipment at your site. |
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2. Obtain a registered IP address for your network | Your network must have a unique IP address if you plan to communicate outside your local network, for example, over the Internet. | Refer to Obtaining Your Network's IP Number. |
3. Devise an IP addressing scheme for your systems, based on your IPv4 network prefix or IPv6 site prefix. | Determine how addresses are to be deployed at your site. | Refer to Designing an IPv4 Addressing Scheme or refer to Preparing an IPv6 Addressing Plan. |
4. Create a list that contains the IP addresses and host names of all machines on your network. | Use the list to build network databases | Refer to Network Databases |
5. Determine which name service to use on your network. | Decide whether to use NIS, LDAP, DNS, or the network databases in the local /etc directory. | |
6. Establish administrative subdivisions, if appropriate for your network | Decide if your site requires that you divide your network into administrative subdivisions | Refer to Administrative Subdivisions |
7. Determine where to place routers in the network design. | If your network is large enough to require routers, create a network topology that supports them. | Refer to Planning for Routers on Your Network |
8. If required, design a strategy for subnets. | You might need to create subnets for administering your IP address space or to make more IP addresses available for users. | For IPv4 subnet planning, refer to What Is Subnetting? For IPv6 subnet planning, refer to Creating a Numbering Scheme for Subnets |
Determining the Network Hardware
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 must make involve the following network hardware:
The network topology, the layout, and connections of the network hardware
The number of host systems your network can support
The types of hosts that the network supports: standalone and dataless
The types of servers that you might need
The type of network media to use: Ethernet, Token Ring, FDDI, and so on
Whether you need bridges or routers extend this media or connect the local network to external networks
Whether some systems need separately purchased interfaces in addition to their built in interfaces
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.
Deciding on an IP Addressing Format for Your Network
The number of systems that you expect to support affects how you configure your network. Your organization might require a small network of several dozen standalone systems that are located on one floor of a single building. Alternatively, you might need to set up a network with more than 1,000 systems in several buildings. This setup can require you to further divide your network into subdivisions that are called subnets.
When you plan your network addressing scheme, consider the following factors:
The type of IP address that you want to use: IPv4 or IPv6
The number of potential systems on your network
The number of systems that are multihomed or routers, which require an IP address for each interface
Whether to use private addresses on your network
Whether to have a DHCP server that manages pools of IPv4 addresses
The worldwide growth of the Internet since 1990 has resulted in a shortage of available IP addresses. To remedy this situation, the Internet Engineering Task Force (IETF) has developed a number of IP addressing alternatives. Types of IP addresses in use today include the following:
If your organization has been assigned more than one IP address for your network or uses subnets, appoint a centralized authority within your organization to assign network IP addresses. That authority should maintain control of a pool of assigned network IP addresses, and assign network, subnet, and host addresses as required. To prevent problems, ensure that duplicate or random network numbers do not exist in your organization.
IPv4 Addresses
These 32-bit addresses are the original IP addressing format that was designed for TCP/IP. Originally, IP networks have three classes, A, B, and C. The network number that is assigned to a network reflects this class designation plus 8 or more bits to represent a host. Class-based IPv4 addresses require you to configure a netmask for the network number. Furthermore, to make more addresses available for systems on the local network, these addresses were often divided into subnets.
Today, IP addresses are referred to as IPv4 addresses. Although you can no longer obtain class-based IPv4 network numbers from an ISP, many existing networks still have them. For more information about administering IPv4 addresses, refer to Designing Your IPv4 Addressing Scheme.
IPv4 Addresses in CIDR Format
The IETF has developed Classless Inter-Domain Routing (CIDR) addresses as a short to medium term fix for the shortage of IPv4 addresses. In addition, CIDR format was designed as a remedy to the lack of capacity of the global Internet routing tables. An IPv4 address with CIDR notation is 32 bits in length and has the same dotted decimal format. However, CIDR adds a prefix designation after the rightmost byte to define the network portion of the IPv4 address. For more information, refer to Designing Your CIDR IPv4 Addressing Scheme.
DHCP Addresses
The Dynamic Host Configuration Protocol (DHCP) protocol enables a system to receive configuration information from a DHCP server, including an IP address, as part of the booting process. DHCP servers maintain pools of IP address from which to assign addresses to DHCP clients. A site that uses DHCP can use a smaller pool of IP addresses than would be needed if all clients were assigned a permanent IP address. You can set up the Solaris DHCP service to manage your site's IP addresses, or a portion of the addresses. For more information, refer to Chapter 12, About Solaris DHCP (Overview).