User Manual

6-1
6: IP
This chapter explains some important concepts about IP addressing, configuration, and routing.
To configure IP for remote networking, see Chapter 4, Basic Remote Networking, and Chapter 5, Additional
Remote Networking. For specific IP commands, see IP/Network Commands on page 12-16.
This chapter is divided as follows:
◆ IP Addresses, page 6-1, describes how the SCS handles IP address assignment.
◆ Subnet Masks, page 6-5, explains how the SCS works with subnetworks.
◆ Name Resolving, page 6-6 discusses name resolution.
◆ Header Compression, page 6-8, covers how to enable and disable IP header compression.
◆ Establishing Sessions, page 6-8, describes SSH, Telnet, and Rlogin sessions.
◆ IP Security, page 6-14, discusses how to configure the IP security table.
◆ Displaying the IP Configuration, page 6-20, explains the parameters of the Show IP command.
◆ Examples, page 6-22, shows examples of the SCS in various real-life situations.
6.1 IP Addresses
Each TCP/IP node on a network has a unique IP address. The IP address provides the information needed
to forward packets on the local network and across multiple networks if necessary. IP addresses are
specified as n.n.n.n, where each n is a number from 0 to 254; for example, 192.0.1.99.
You must assign the SCS a unique IP address. This IP address will also be used for each individual serial
port on the SCS.
IP addresses contain three pieces of information: the network, the subnet, and the host. The network
portion of the IP address is determined by the network type: Class A, B, or C.
Table 6-1: Network Portion of IP Address
Network Class Network Portion of Address
Class A First byte (2nd, 3rd, and 4th bytes are the host)
Class B First 2 bytes (3rd and 4th bytes are the host)
Class C First 3 bytes (4th byte is the host)