Loopback

Loopback interfaces are virtual logical interfaces that provide a stable, always-up reference point for network services including routing protocol router IDs, management access, and service endpoints that remain accessible regardless of physical interface states. They support full Layer 3 functionality including IPv4 and IPv6 addressing, routing protocol participation (OSPF, BGP), MPLS services, and advanced features such as BFD for fast failure detection and network monitoring applications. Loopback interfaces are essential for network design best practices, providing consistent reachability for critical services, enabling effective network troubleshooting, and serving as anchor points for overlay networks, VPN services, and network management systems.

Diagram

Classes

interfaces (iosxe.devices.configuration)

Name	Type	Constraint	Mandatory	Default Value
loopbacks	List	`[loopbacks]`	No

loopbacks (iosxe.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory
id	Integer		Yes
interface_groups	List	String	No
description	String		No
shutdown	Boolean	`true`, `false`	No
vrf_forwarding	String		No
ipv4	Class	`[ipv4]`	No
ipv6	Class	`[ipv6]`	No
arp_timeout	Integer	min: `0`, max: `2147483`	No
load_interval	Integer	min: `30`, max: `600`	No
mpls	Class	`[mpls]`	No
ospf	Class	`[ospf]`	No
ospfv3	Class	`[ospfv3]`	No
pim	Class	`[pim]`	No

ipv4 (iosxe.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory
address	IP		No
address_mask	IP		No
proxy_arp	Boolean	`true`, `false`	No
access_group_in	String		No
access_group_out	String		No
redirects	Boolean	`true`, `false`	No
unreachables	Boolean	`true`, `false`	No
unnumbered	String		No

ipv6 (iosxe.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory
enable	Boolean	`true`, `false`	No
addresses	List	`[addresses]`	No
link_local_addresses	List	IP	No
address_autoconfig_default	Boolean	`true`, `false`	No
address_dhcp	Boolean	`true`, `false`	No
mtu	Integer	min: `1280`, max: `9976`	No

mpls (iosxe.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory	Default Value
ip	Boolean	`true`, `false`	No
mtu	Integer		No

ospf (iosxe.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory
cost	Integer	min: `1`, max: `65535`	No
dead_interval	Integer	min: `1`, max: `65535`	No
hello_interval	Integer	min: `1`, max: `65535`	No
mtu_ignore	Boolean	`true`, `false`	No
network_type	Choice	`broadcast`, `non-broadcast`, `point-to-multipoint`, `point-to-point`	No
priority	Integer	min: `0`, max: `255`	No
ttl_security_hops	Integer	min: `1`, max: `254`	No
process_ids	List	`[process_ids]`	No
message_digest_keys	List	`[message_digest_keys]`	No

ospfv3 (iosxe.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory	Default Value
network_type	Choice	`broadcast`, `non-broadcast`, `point-to-multipoint`, `point-to-point`	No
cost	Integer	min: `1`, max: `65535`	No

pim (iosxe.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory
passive	Boolean	`true`, `false`	No
dense_mode	Boolean	`true`, `false`	No
sparse_mode	Boolean	`true`, `false`	No
sparse_dense_mode	Boolean	`true`, `false`	No
bfd	Boolean	`true`, `false`	No
border	Boolean	`true`, `false`	No
bsr_border	Boolean	`true`, `false`	No
dr_priority	Integer	min: `0`, max: `4294967294`	No

addresses (iosxe.devices.configuration.interfaces.loopbacks.ipv6)

Name	Type	Constraint	Mandatory	Default Value
prefix	IP		Yes
eui_64	Boolean	`true`, `false`	No

process_ids (iosxe.devices.configuration.interfaces.loopbacks.ospf)

Name	Type	Constraint	Mandatory	Default Value
id	Integer	min: `1`, max: `65535`	No
areas	List	String	No

message_digest_keys (iosxe.devices.configuration.interfaces.loopbacks.ospf)

Name	Type	Constraint	Mandatory
id	Integer	min: `1`, max: `255`	Yes
md5_auth_key	String		No
md5_auth_type	Choice	`0`, `7`	No

Examples

iosxe:
  devices:
    - name: Device1
      configuration:
        interfaces:
          loopbacks:
            - id: 0
              description: Loopback0
              ip_address: 5.5.5.5
              ip_address_mask: 255.255.255.0

Full example:

iosxe:
  devices:
    - name: Device1
      configuration:
        interfaces:
          loopbacks:
            - id: 1
              description: Production Loopback 2
              shutdown: false
              vrf_forwarding: prod
              arp_timeout: 30
              load_interval: 30
              ipv4:
                address: 192.168.2.1
                address_mask: 255.255.255.0
                proxy_arp: true
                access_group_in: ACL_IN
                access_group_out: ACL_OUT
                redirects: false
                unreachables: false
              ipv6:
                enable: true
                addresses:
                  - prefix: 2001::1
                    prefix_length: 64
                link_local_addresses:
                  - fe80::1
                mtu: 1450
              bfd:
                enable: true
                local_address: 172.16.1.1
                interval: 120
                interval_multiplier: 3
                interval_min_rx: 100
                echo: false
              mpls:
                mtu: 1450
                ip: true
              ospf:
                cost: 50
                dead_interval: 3
                hello_interval: 1
                mtu_ignore: true
                network_type: point-to-multipoint
                priority: 1
                ttl_security_hops: 2
                process_ids:
                  - id: 1
                    areas:
                      - "0.0.0.0"
              ospfv3:
                network_type: point-to-point
                cost: 50
              pim:
                dense_mode: true
                bfd: true
                border: true
                bsr_border: true
                dr_priority: 100