156 ITG engineering guidelines
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, butthe 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 packetizedvoice 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 Trunk3.01 (and later) ELAN subnet
because remote support access is provided by Remote Access Server
(RAS) on the TLAN subnet.
•Remote support access is not required, and there is no firewall router
between the ELAN subnet and the TLAN subnet.
Nortel Communication Server 1000
IP TrunkFundamentals
NN43001-563 02.01 Standard
Release 5.5 21 December 2007
Copyright© 2007, Nor tel Networks
.