Let's check that I can failover and could use the loopback. The first path is not going to be available anymore. If I do a show ip route now, I can see the I can still ping That's the way we want to use loopbacks.
We can get to our routers no matter what path we've got available and still using the same IP address. Is there connectivity to the loopback interfaces from the PCs? Why or why not? There is no connectivity from the PCs to the loopback interfaces because they are not in the routing tables of the routers apart from the local loopback interface on each router. The loopback interfaces are not in the routing tables because they are in the C D An interface might be unavailable because of a problem unrelated to the device's configuration or operation.
You can use the loopback interface to address these issues. The loopback interface is always up and it is reachable as long as the route to that IP address is available in the IP routing table. Hence you can use the loopback interface for diagnostics and troubleshooting purposes. Protocols such as OSPF use the loopback address to determine protocol-specific properties for the device or network.
Further, some commands such as ping mpls require a loopback address to function correctly. For most purposes, though, it is only necessary to use one IP address, and that is This IP has the hostname of localhost mapped to it. Like other network adapters, the loopback device shows up in the output of ifconfig. Its name is lo. One common, production i. In a web browser, go to:. All the If you come from a Windows background, you might expect loopback to itself be a synonym of localhost and thus to be able to ping loopback , connect to servers on loopback , and so forth.
That behavior is peculiar to Windows. The general concept of loopback is a mechanism through which a message or signal ends up or loops back to where it started. So there are a few other ways loopback is use in Ubuntu that should not be confused with the loopback device in networking. This is usually called a loop device and not a loopback device , but the term loopback file interface is occasionally used.
Pulseaudio's loopback module facilitates this. Here, it is correct to use the term loopback , but like loop mounts, this also has nothing to do with the loopback device in networking. And nothing to do with loop mounts, either. Ubuntu Community Ask! Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. In the same way, if you configure a loopback interface lo1 with IP address You can configure multiple IP addresses on a loopback interface lo0 to lo7.
Up to thirty-two IP addresses are supported on a loopback interface. The following example shows valid IP address configurations on two loopback interfaces. To display the list of loopback interfaces which have been assigned IP addresses, enter the show ip command.
The following example displays the IP addresses configured for two user-defined loopback interfaces lo1 and lo2. To display the default loopback address, enter the show ip route command as shown in the example below.
To display the loopback interfaces configured on the switch in a list of IP routing entries displayed according to destination IP address, enter the show ip route command.
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