ATM VPI/VCI

[nbhungalia]

I tried to configure VPI/VCI 1/888 on my IMA circuit and router didn't like it. The highest VPI/VCI it will let me configure is 1/255. I was wondering if there was any limitations on that. If anyone has any ideas, I would appreciate it. Thanks

[pkhatri · Accepted solution]

Hi,

I'm not sure what platform you are attempting this on but on quite a few platforms, the total amount of bit-space available for VPI+VCI on the SAR chip is limited to a number less than what the ATM standards state.

On most of the IOS-based platforms, you can configure higher VCI values by sacrificing the VPI range. The command usually used to do this is: 'atm vc-per-vp' or something similar.

For example, on certain platforms, the max amount of bits available for VPI+VCI is 14 bits. So you could, for example, use 4 bits for VPI (0-15) and 10 bits for VCI (0-1023).

Hope that helps,

Paresh.

[nbhungalia]

This is on Cisco 3745 router running IOS 12.2(15)T14

[smif101 · Accepted solution]

Try using the command

atm vc-per-vp 1023

This will allow you a lower amount of VPI's (1-15) that in turn will grant you a higher number of VCI's.