Subnet Addressing - Avaya 8800 Configuration Manual

Figure 1: Network and host boundaries in IP address classes
IPv6 addresses use a greater number of bits than IPv4 addresses. IPv4 addresses are 32 bits
long and expressed in decimal, whereas IPv6 addresses are 128 bits long and expressed in
hexadecimal. An example of an IPv6 address is 3ffe:1900:4545:3:200:f8ff:fe21:67cf.

Subnet addressing

Subnetworks (or subnets) extend the IP addressing scheme used by an organization to one
with an 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).
Create a subnet address by increasing the network portion to include a subnet address, thus
decreasing the host portion of the IP address. For example, in the address 128.32.10.0, the
network portion is 128.32, while the subnet is in the first octet of the host portion (10). A subnet
mask is applied to the IP address and identifies the network and host portions of the
address.
The following table illustrates how subnet masks can create differing numbers of subnets and
hosts. This example includes using the zero subnet, which is permitted on an Avaya Ethernet
Routing Switch 8800/8600.
Table 2: Subnet masks for class B and class C IP addresses
Number
of bits
Configuration — OSPF and RIP
Subnet mask Number of subnets
(recommended)
Class B
IP addresses
Number of hosts for
each subnet
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