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+lastproofread  
+2023-01-20
+
+# 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.
+
+<div class="note">
+
+<div class="title">
+
+Note
+
+</div>
+
+There can only be one loopback `lo` interface on the system. If
+you need multiple interfaces, please use the `dummy-interface`
+interface type.
+
+</div>
+
+<div class="hint">
+
+<div class="title">
+
+Hint
+
+</div>
+
+A loopback interface is always up, thus it could be used for
+management traffic or as source/destination for and `IGP (Interior
+Gateway Protocol)` like `routing-bgp` so your internal BGP link is not
+dependent on physical link states and multiple routes can be chosen to the
+destination. A `dummy-interface` Interface should always be preferred
+over a `loopback-interface` interface.
+
+</div>
+
+## Configuration
+
+### Common interface configuration
+
+<div class="cmdinclude" var0="loopback" var1="lo">
+
+/\_include/interface-address.txt
+
+</div>
+
+<div class="cmdinclude" var0="loopback" var1="lo">
+
+/\_include/interface-description.txt
+
+</div>
+
+## Operation
+
+<div class="opcmd">
+
+show interfaces loopback
+
+Show brief interface information.
+
+``` 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
+```
+
+</div>
+
+<div class="opcmd">
+
+show interfaces loopback lo
+
+Show detailed information on the given loopback interface <span class="title-ref">lo</span>.
+
+``` none
+vyos@vyos:~$ show interfaces loopback lo
+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
+```
+
+</div>