Nortel Networks NN43001-563 - Manual (Page 157)

IP Trunk 3.01 (and later) LAN installation and configuration 157
The TLAN subnet has a range of addresses from 10.0.0.1 to 10.0.0.127.
The ELAN subnet is in a separate subnet, with a range of addresses from
10.0.0.129 to 10.0.0.160. This configuration results in smaller TLAN subnet
addresses, but it fulfills the requirement that subnets do not overlap.
Selecting public or private IP addresses
Consider a number of factors to determine if the TLAN and ELAN subnets
will use private (internal IP addresses) or public IP addresses.
Private IP addresses
Private IP addresses are internal IP addresses that are not routed over the
internet. They can be routed directly between separate intranets, provided
that there are no duplicated subnets in the private IP addresses. Private IP
addresses can be used to configure the TLAN and ELAN subnets, so that
scarce public IP addresses are used efficiently.
Three blocks of IP addresses have been reserved for private intranets:
• 10.0.0.0 – 10.255.255.255
• 172.16.0.0 – 172.31.255.255
• 192.168.0.0 – 192.168.255.255
Some routers and firewalls provide a Network Address Translation (NAT)
function that allows the customer to map a registered globally unique public
IP address to a private IP address without re-numbering an existing private
IP address autonomous domain. NAT allows private IP addresses to be
accessed selectively over the internet.
Public IP addresses
Public IP addresses can be used for the TLAN and ELAN subnets, but
consume limited resources.
This has the same result as the private IP address solution, but the ELAN
subnet is accessible from the internet without NAT.
Single subnet option for voice and management
Although not recommended, the "single subnet" option for voice and
management could be used in the following situations:
• The combined voice and management traffic on the ELAN subnet is so
low that there is no impact on packetized voice QoS performance.
• The customer is willing to tolerate occasional voice quality impairments
caused by excessive management traffic.
• There is no modem router on the IP Trunk 3.01 (and later) ELAN subnet
because remote support access is provided by Remote Access Server
(RAS) on the TLAN subnet.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.