Loopback interfaces

A loopback interface is a software-only interface that emulates a physical interface. This interface is reachable on IPv4 and IPv6 through multiple physical interfaces. The loopback interface helps to overcome path failures. It is accessible from any physical interface. If one interface goes down, you can access the loopback interface from another.

Loopback interfaces can be used for:

  • AAA

  • BGP

  • DNS

  • HTTP

  • ICMP

  • IPsec flow offload—Secure Firewall 1200/3100/4200 /6100 only

  • NetFlow

  • SNMP

  • SSH

  • Static and dynamic VTI tunnels

  • Syslog

The Firewall Threat Defense can distribute the loopback address using dynamic routing protocols, or you can configure a static route on the peer device to reach the loopback IP address through one of the Firewall Threat Defense's physical interfaces. You cannot configure a static route on the Firewall Threat Defense that specifies the loopback interface.