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diff --git a/docs/interfaces/loopback.rst b/docs/interfaces/loopback.rst new file mode 100644 index 00000000..f7519631 --- /dev/null +++ b/docs/interfaces/loopback.rst @@ -0,0 +1,75 @@ +.. _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 <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 <description> + + Assign given `<description>` 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: <LOOPBACK,UP,LOWER_UP> 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 |