How To Configure Virtual Interfaces - Cisco 6000 Series Configuration Manual

Configuring Virtual Loopback and Null Interfaces
After switchover, the virtual interfaces all are present on the standby (now active) RP. Their state and
configuration are unchanged and there has been no loss of forwarding (in the case of tunnels) over the interfaces
during the switchover. The routers use nonstop forwarding (NSF) over bundles and tunnels through the
switchover of the host RP.
Note
The user need not configure anything to guarantee that the standby interface configurations are maintained.
Note Protocol configuration such as tacacs source-interface, snmp-server trap-source, ntp source, logging
source-interface do not use the virtual management IP address as their source by default. Use the ipv4 virtual
address use-as-src-addr command to ensure that the protocol uses the virtual IPv4 address as its source
address. Alternatively, you can also configure a loopback address with the designated or desired IPv4 address
and set that as the source for protocols such as TACACS+ using the tacacs source-interface command.

How to Configure Virtual Interfaces

This section contains the following procedures:
Configuring Virtual Loopback Interfaces
This task explains how to configure a basic loopback interface.
Note The IP address of a loopback interface must be unique across all routers on the network. It must not be used
by another interface on the router, and it must not be used by an interface on any other router on the network.
SUMMARY STEPS
1. configure
2. interface loopback interface-path-id
3. ipv4 address ip-address
4. Do one of the following:
5. show interfaces type interface-path-id
DETAILED STEPS
Command or Action
Step 1
configure
Example:
Interface and Hardware Component Configuration Guide for Cisco NCS 6000 Series Routers, IOS XR Release 6.4.x
• end
• commit
How to Configure Virtual Interfaces
Purpose
Enters XR configuration mode.
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