Cabletron Systems EMM-E6 Ethernet manual IP Addresses

REVIEW OF ADDRESSING

As MAC addresses are often used to perform management and control functions for networking hardware, it is important to be able to identify a MAC address when it is requested or returned by network management. Since most MAC addresses are set at manufacture and cannot be altered by users, this manual does not examine MAC addressing in greater detail.

1.10.2IP Addresses

Each network interface or TCP/IP host is identified by a 32-bit binary number called the Internetwork Protocol (IP) address. An IP address represents a connection to the network, but does not identify any specific physical device location (physical locations are determined by MAC Addresses, discussed earlier in this chapter). Every IP address is made up of four 8-bit binary numbers (octets). Each octet is translated into its decimal equivalent and represented using Dotted Decimal Notation (DDN). The DDN format is XXX.XXX.XXX.XXX. Any of the four DDN values, called fields, can range from 1 (octet 0000 0001) to 255 (octet 1111 1111). An IP address is made up of two portions, the Network ID and a Host ID. Network IDs refer to a particular network and are assigned by the Internet Assigned Numbers Authority (IANA). The IANA assigns fixed numbers to one, two, or three of the fields in order to provide a unique Network ID.

Once a Network ID has been assigned, the Network Manager assigns individual Host IDs by configuring different values (within the allowable ranges) for the octets not set by the IANA. This allows individual hosts on the network to be identified by distinct numerical addresses.

There are three classes of IP addresses which define the Network and Host ID numbering scheme. Tables 1-1 through 1-3 describe the classes. The bold type in these tables indicates a field assigned by the IANA, the Network ID. Any time the term “host” is found in the DDN format example address, it indicates a Host ID field, which may be assigned by the network manager.

EMM-E6 User’s Guide 1-23