Cat 2950, Version 12.1(22)EA4a Can't Configure Loopback Interface

[tanbc3323]

Hi,

Like to check, is it all the Cat 2950 can create the loopback interface ?

Currently i got one Cat 2950 with Ver 12.1(22)EA4a with is can't be create the loopback interface. Any ideal ?

Please refer to attachment that i captured. Thanks !

[pkhatri]

Hi,

The reason for this is that the switch does not support IP routing - it is a layer 2 switch only.

That is why it does not make sense to be able to use loopback interfaces on the switch.

Hope that helps - pls rate the post if it does.

Paresh

[ankurbhasin]

The software will show you the presence of loopback option after interface command but this command is not supported in hardware as it is a layer 2 switch.

The IOS developed by Cisco is the general release and has some common commands but those commands will only be working if proper hardware is found.

A software loopback is a layer 3 interface and the 2950 is a layer 2 switch;the switch would need to support L3 for a loopback to work.

So this will not work on 2950 switch but will work on 3550 switch and above which are layer 3 switches.

HTH, please rate all post.

Ankur

[tanbc3323]

Hi,

Can explain more why loopback interface just apply on L3 and not L2 ? Thanks !

[pkhatri]

Hello,

A loopback address is generally used for things such as assigning router IDs for protocols such as BGP and OSPF. This means that an IP address is configured on the loopback interface which is then used by these protocols as a router ID. There are other valid uses as well: on IBGP routers, you would configure BGP sessions between loopback addresses, again IP addresses.

Now, with a L2 switch, you don't get L3 capability, except for management. Therefore, there isn't much that you can use a loopback interface for.

Hope that helps - pls rate the post if it does.

Paresh