Single Subnet Option For Voice And Management - Nortel 1000 Description, Installation And Operation Manual

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.
• Remote support access is not required, and there is no firewall router
between the ELAN subnet and the TLAN subnet.
ITG engineering guidelines
IP Trunk Description, Installation, and Operation
Page 211 of 644