max. number of loopback interfaces on a 3560-8PC-S or a 2960TC-8-L

[ciscoprolin]

Dear community,

our application monitoring engineer needs to be able to ping thousands of IP addresses and we decided to offer the following solution to him:  a Cisco 8 port Office Switch such as a 3560-8PC-S or a 2960TC-8-L.

The Problem we're now facing is that only up to 64 loopback Interfaces (0 - 63) could be created. It's not possible to create a loopback Interface with the num value 64 or higher. Any ideas what we could do to resolve this issue ?

We're running IOS 12.2(55)EX2. Peculiarly, 0-2147483647 is offered when you enter Interface loopback ?  but fact is we can't generate a loopback Interface 64 or higher.

Switch(config)#int lo ?
  <0-2147483647>  Loopback interface number

Thanks very much and best regards,

Thorsten

[Karsten Iwen]

I'm not sure if I really understand your needs, but with the help of secondary addresses, an interface can have more than one ip-address configured. But I never tested if that really scales to "thousands" ...

[ciscoprolin]

Hi Karsten,

thanks. Secondary IP's would also be an option. That's a good idea. I have just found out that more than 64 loopbacks are possible with IOS version 15.x. With 12.x it's limited.

Thanks,

Thorsten

[ciscoprolin]

Hi,

sorry my previous statement was not 100% correct. While I was able to create a loopback interface with the num value 64 I was again not able to create more than 64 loopbacks in the sum with IOS 15. So the question is still open.

Do I maybe need IP Services on a L3based switch ?

Thanks for your help,

Thorsten

[Karsten Iwen · Accepted solution]

Just tested it on a WS-C3560-8PC with 15.0(2)SE5 IPServices, and also there it stopped after 64 Loopbacks.

What about a small Linux-PC for that?

[ciscoprolin]

Hi Karsten,

thanks. I think I will go for the alternative solution and try it with IP secondaries on just one loopback interface. I was able to create 2000 IP secondaries under one loopback interface (probably even more would have been possible but 2000 are sufficient for the moment). Thanks so much for your appreciated help.

Cheers,

Thorsten

[ciscoprolin]

Hi Karsten,

thanks. Secondary IP's would also be an option. That's a good idea. I have just found out that more than 64 loopbacks are possible with IOS version 15.x. With 12.x it's limited.

Thanks,

Thorsten