:lastproofread: 2023-01-20 .. _dummy-interface: ##### Dummy ##### The dummy interface is really a little exotic, but rather useful nevertheless. Dummy interfaces are much like the :ref:`loopback-interface` interface, except you can have as many as you want. .. note:: Dummy interfaces can be used as interfaces that always stay up (in the same fashion to loopbacks in Cisco IOS), or for testing purposes. .. hint:: On systems with multiple redundant uplinks and routes, it's a good idea to use a dedicated address for management and dynamic routing protocols. However, assigning that address to a physical link is risky: if that link goes down, that address will become inaccessible. A common solution is to assign the management address to a loopback or a dummy interface and advertise that address via all physical links, so that it's reachable through any of them. Since in Linux-based systems, there can be only one loopback interface, it's better to use a dummy interface for that purpose, since they can be added, removed, and taken up and down independently. ************* Configuration ************* Common interface configuration ============================== .. cmdinclude:: /_include/interface-address.txt :var0: dummy :var1: dum0 .. cmdinclude:: /_include/interface-description.txt :var0: dummy :var1: dum0 .. cmdinclude:: /_include/interface-disable.txt :var0: dummy :var1: dum0 .. cmdinclude:: /_include/interface-vrf.txt :var0: dummy :var1: dum0 ********* Operation ********* .. opcmd:: show interfaces dummy Show brief interface information. .. code-block:: none vyos@vyos:~$ show interfaces dummy Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down Interface IP Address S/L Description --------- ---------- --- ----------- dum0 172.18.254.201/32 u/u .. opcmd:: show interfaces dummy <interface> Show detailed information on given `<interface>` .. code-block:: none vyos@vyos:~$ show interfaces dummy dum0 dum0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 26:7c:8e:bc:fc:f5 brd ff:ff:ff:ff:ff:ff inet 172.18.254.201/32 scope global dum0 valid_lft forever preferred_lft forever inet6 fe80::247c:8eff:febc:fcf5/64 scope link valid_lft forever preferred_lft forever RX: bytes packets errors dropped overrun mcast 0 0 0 0 0 0 TX: bytes packets errors dropped carrier collisions 1369707 4267 0 0 0 0