.. _loopback-interface: ######## Loopback ######## The loopback networking interface is a virtual network device implemented entirely in software. All traffic sent to it "loops back" and just targets services on your local machine. .. note:: There can only be one loopback ``lo`` interface on the system. If you need multiple interfaces, please use the :ref:`dummy-interface` interface type. .. hint:: A lookback interface is always up, thus it could be used for management traffic or as source/destination for and :abbr:`IGP (Interior Gateway Protocol)` like :ref:`bgp` so your internal BGP link is not dependant on physical link states and multiple routes can be choosen to the destination. A :ref:`dummy-interface` Interface should always be preferred over a :ref:`loopback-interface` interface. Configuration ============= Address ------- .. cfgcmd:: set interfaces loopback lo address
Configure Loopback interface `lo` with one or more interface addresses. Address can be specified multiple times as IPv4 and/or IPv6 address, e.g. 192.0.2.1/24 and/or 2001:db8::1/64. Link Administration ------------------- .. cfgcmd:: set interfaces loopback lo description Assign given `` to interface `lo`. Description will also be passed to SNMP monitoring systems. Operation ========= .. opcmd:: show interfaces loopback Show brief interface information. .. code-block:: none vyos@vyos:~$ show interfaces loopback Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down Interface IP Address S/L Description --------- ---------- --- ----------- lo 127.0.0.1/8 u/u ::1/128 .. opcmd:: show interfaces loopback lo Show detailed information on given loopback interface `lo`. .. code-block:: none vyos@vyos:~$ show interfaces ethernet eth0 lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever RX: bytes packets errors dropped overrun mcast 300 6 0 0 0 0 TX: bytes packets errors dropped carrier collisions 300 6 0 0 0 0