# Loopback Interface Configuration Mode Commands

Use the Loopback Interface Configuration mode to create and manage loopback interfaces that provide IP addresses that are always available and reachable from any interface within a given context.

IMPORTANT:

The commands or keywords/variables that are available are dependent on platform type, product version, and installed license(s).
crypto-map

Applies the specified IPSec crypto-map to this interface.
Platform:

ASR 5000

ASR 5500
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    crypto-map map_name [ secondary-address
     sec_ip_addr ]

no

Deletes the application of the crypto map on this interface.
map_name

Specifies the name of the crypto map being applied. The name is an alphanumeric string of 1 through 127 characters that is case sensitive.
secondary-address sec_ip_addr

Applies the crypto map to the secondary address for this interface that is specified by sec_ip_addr. sec_ip_addr must be specified using the IPv4 dotted-decimal or IPv6 colon-separated-hexadecimal notation.
Usage:

In order for ISAKMP and/or manual crypto maps to work, they must be applied to a specific interface using this command. Dynamic crypto maps should not be applied to interfaces.

The crypto map must be configured in the same context as the interface.
Example:
To apply the IPSec crypto map named cmap1 to this interface, use the following command:

    crypto-map  cmap1

description

Use this command to configure the descriptive text for the current interface.
Platform:

ASR 5000

ASR 5500
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    description textno description

no

Clears the description for the interface.
text

Specifies the descriptive text to use. Fortext, enter an alphanumeric string of 0 through 79 characters. If spaces or special characters are required, the stirng must be bracketed with double quotation marks.
Usage:

Set the description to provide any useful information on the interface’s primary function, services, end users.
Example:

    description sampleInterfaceDescriptiveText

end

Exits the current configuration mode and returns to the Exec mode.
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    end

Usage:

Use this command to return to the Exec mode.
exit

Exits the current mode and returns to the parent configuration mode.
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    exit

Usage:

Use this command to return to the parent configuration mode.
ip address

Use this command to configure the IP options for the current interface.
Platform:

ASR 5000

ASR 5500
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    ip address { ip_address ip_mask | ip_address/bitmask } [ secondary | srp-activate ]

    no ip address ip_address

no

Deletes the IP address you specify from the interface configuration.
address {ip_address ip_mask | ip_address/bitmask} [ secondary | srp-activate ]

Configures the IP address and network mask for the interface.

Enter an ip_address ip_mask to specify an IP address and the subnet mask pair that identifies the IP address of the interface. ip_address is entered in IPv4 dotted-decimal or IPv6 colon-separated-hexadecimal notation. Currently, the only value accepted for ip_mask is 255.255.255.255 (IPv4) or 120 (IPv6) .

For the network mask, ip_address/net_mask, enter the IP address and the length in bits of the network mask, Fo example, 192.168.1.0/32 (IPv4) or fe80::c0a8:100/32 (IPV6). Currently, the only value accepted for bit_mask is 32.

Use the secondary keyword ito configure a secondary IP address on the interface. This is referred to as multi-homing of the interface.

Use the srp-activate keyword to activate the IP address for Interchassis Session Recovery (ICSR).
Usage:

Create and manage loopback interfaces for the current context.
Example:
The following command configures IP address to associate with the interface:

    ip address 1.2.3.4 255.255.255.255

The following command removes the associated IP address for the interface:

    no ip address 10.2.3.4

ip vrf

Use this command to configure the IP VPN Routing Forwarding (VRF) instance for the current interface.
Platform:

ASR 5000

ASR 5500
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    ip vrf forwarding vrf_nameno vrf forwarding

no

Deletes the IP VRF instance you specify from the interface configuration.
vrf_name

Specifies the preconfigured IP VRF instance name to be used with this interface.

For vrf_name, enter a VRF instance name that was preconfigured via the ip vrf forwarding command in Context Configuration mode.
Usage:

Use this command to associate a preconfigured IP VRF instance for the current interface.
Example:

The following command associates a preconfigured IP VRF instance named vrf_1 with this interface:

    ip vrf forwarding vrf_1

ipv6 address

Use this command to configure the IPv6 options for the current interface.
Platform:

ASR 5000

ASR 5500
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    ipv6 address ipv6_address ip_mask [ srp-activate ]no iv6p address ipv6_address

no

Deletes the specified IPv6 address from the interface configuration.
address ipv6_address ip_mask

Configures the IP address and network mask for the interface.

ipv6_address ip_mask specifies an IP address and the subnet mask pair that identifies the IPv6 address of the interface. Specify ipv6_address in IPv6 colon-separated-hexadecimal notation.
srp-activate

Activates the IPv6 address for Session Recovery.
Usage:

Create and manage loopback interfaces for the current context and enable Session Redundancy Protocol (SRP) when appropriate.
Example:
The following command configures an IPv6 address to associate with the interface and enables SRP:

    ipv6 address 2001:268:2008:b::1021/128
    srp-activate