Switch User Manual

14 An Introduction to IP Routing Protocols

Class

Address Range Mask

Number of

Networks

Nodes per

Network

224.0.0.0 -

239.255.255.254

Note: Class D addresses are primarily reserved for multicast operations although

the addresses 224.0.0.5 and 224.0.0.6 are used by OSPF and 224.0.0.9 is used

by RIP.

240.0.0.0 -

240.255.255.255

Note: Class E addresses are reserved for research purposes.

To express an IP address in dotted-decimal notation, each octet of the

IP address is converted to a decimal number and separated by decimal

points. For example, the 32-bit IP address 10000000 00100000 00001010

10100111 is expressed in dotted-decimal notation as 128.32.10.167.

Each IP address class, when expressed in binary notation, has a different

boundary point between the network and host portions of the address, as

illustrated in "Network and host boundaries in IP address classes" (page

14). The network portion is a network number ﬁeld from 8 through 24 bits.

The remaining 8 through 24 bits identify a speciﬁc host on the network.

Network and host boundaries in IP address classes

Subnet addressing

Subnetworks (or subnets) are an extension of the IP addressing scheme.

Subnets allow an organization to use one IP address range for multiple

networks. Subnets are two or more physical networks that share a common

network-identiﬁcation ﬁeld (the network portion of the 32-bit IP address).

Nortel Ethernet Routing Switch 5500 Series

Conﬁguration-IP Routing Protocols

NN47200-503 03.01 Standard

5.1 27 August 2007