Loopback Interfaces

Loopback interfaces are internal interfaces available for use in TNSR for routing and other internal traffic handling purposes such as acting as a bridged virtual interface (Bridge Interfaces).

Loopback Configuration

Before a loopback interface can be configured, a loopback instance must be created by the interface loopback <name> command. This command enters config-loopback mode. The loopback must be given a unique name and a positive numeric instance identifier.

The following commands are available in config-loopback mode:

instance:

A required instance identifier. This value is used to generate the loopback interface name in TNSR in the form of loop<id>. For example, with an id of 1, the loopback interface name is loop1.

description:

A brief text description of this loopback instance.

mac-address:

An optional MAC address to use for the loopback interface. If omitted, TNSR will generate a MAC in the form of de:ad:00:00:00:<id>.

Note

Configurations with more than 256 loopback interfaces must define unique MAC addresses for each interface manually.

TNSR will generate a maximum of 256 automatic MAC addresses in this format, 00 through FF. After reaching 256 automatic MAC addresses, new addresses will start over again at 00 and conflict with the automatic addresses on earlier interfaces.

Loopback Example

This example creates a new loopback object named mgmtloop with an instance identifier of 1:

tnsr(config)# interface loopback mgmtloop
tnsr(config-loopback)# instance 1
tnsr(config-loopback)# exit

Upon commit, the new interface will be available for use by TNSR. The interface will be designated loop<instance id>, in this case, loop1. It can then be configured in the same manner as other interfaces:

tnsr(config)# interface loop1
tnsr(config-interface)# ip address 10.25.254.1/24
tnsr(config-interface)# exit