CDP and ATM interfaces

[rshout]

We are migrating the core of our WAN network from frame relay to ATM. The WAN backbone consists of 7200VXR routers connected to IGX8410s over ATM/OC3, with the IGX8410s interconnected via ATM/T3. A large number of small remote sites will be connected to this network as frame relay on the remote side.

Anyway, apparently CDP is not supported on ATM interfaces. In the past, I have found this feature to be useful in both troubleshooting and for network managment related tasks.

Is their any way to get CDP to work over ATM interfaces or to obtain the same information in some other way?

And just out of curiosity, why isn't CDP supported on ATM interfaces and will it ever be supported?

Thanks in advance.

[p.guillaume]

CDP is supported over atm...

[rshout]

Yes, and no. Here is the response I got from Cisco which pretty much answers my question and offers some hope:

A couple of different issues to your question. As far as CDP on ATM, it is not supported on ATM PVCs, only LANE at this time. There is a feature request for it to be added, but it will not be complete until later 12.2 code (see more details below).

As for Interworking, as you are aware to convert frame to cells, the data gets pulled out of the frame, put into cells, then put back into a new frame. This conversion causes protocol identification (CDP) to be lost. The spec for SIW doesn't specify how to convert CDP since CDP is proprietary. This can be seen by the "unknown protocol errors" which indicates that CDP is being dropped. Unfortunately, I am told there is no request to have this added to the specs. Let me know if this answers your questions. Otherwise, I will go ahead and close the case by close of business today.

[bryan-gregory]

Yes, I agree with you rshout. In the near future.

[szemi]

Robert,

Did you manage to get more specific info about CDP over ATM PVCs? When will that "later" 12.2 IOS come out? I would need some way to make CDP run over PVCs to be able to display them in CW2000.

Maybe you could send me the TAC case number you opened in this matter...

Thanks in advance,

Andras

[o.montee]

dear,

When is foreseen the IOS supporting CDP over ATM and which is the version ?

Is this version already available on Cisco web site ?

[ryan.hicks]

One reason why it is not supported on anything except LANE is because layer 2 cdp packets show up as errors in the frf.8 SIW (frame to ATM conversion) and some carriers discard them. If you are looking to manage these devices and get stats through Cisco Works usually (on other interfaces) CDP has to be enabled. On ATM interfaces, you would have to have ILMI enabled. ILMI may be what your looking for.

[msperl]

I know CDP is a layer2 feature and ATM only supports

layer3 because AAL5 support

Michael