loopback interface on catalyset switches

[moamen.elhefnawy]

Hello,

I need to know if I can configure loopback interfaces on L2 switches (2950) and if yes , in which IOS

Thanks

Moamen

[ankurbhasin]

Hi Moamen,

As the 2950 is a pure 2nd layer switch, you can only have one active 3rd layer interface on it at any given time. The most logical and usual option is to use a VLAN interface - in fact, I don't think you can use any other type of 3rd layer interface on them.

HTH

Ankur

[glen.grant]

Why would you think you need to use a loopback interface on a layer 2 switch ???

[moamen.elhefnawy]

Hello,

for admin, I need to create loopback interface and use it as the admin IP to reach the switch

I know that the admin ip configured under interface vlan1

but I'm asking because I have a switch that has the int loopback in his menu when using

conf t# int ?

I can found loopback , but I can't configured it

#####

switch(config)#interface ?

Async Async interface

BVI Bridge-Group Virtual Interface

Dialer Dialer interface

FastEthernet FastEthernet IEEE 802.3

Group-Async Async Group interface

Lex Lex interface

Loopback Loopback interface<<<<<

Multilink Multilink-group interface

Null Null interface

Port-channel Ethernet Channel of interfaces

Tunnel Tunnel interface

Virtual-Template Virtual Template interface

Virtual-TokenRing Virtual TokenRing

Vlan Catalyst Vlans

range interface range command

#########

System image file is "flash:c2950-i6q4l2-mz.121-22.EA3"

but when I'm trying to configure it the switch refused

Thanks & BR

Moamen

[ankurbhasin · Accepted solution]

Hi Moamen,

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

[moamen.elhefnawy]

Hello Ankur

Thanks very much , it is clear now

Moamen