11-01-2006 08:28 AM - edited 03-05-2019 12:33 PM
Hi, want to get more informaiton about workings of CDP. In particular about: 1) why CDP needs SNAP encapsualtion 2) does Frame Relay run using SNAP? 3) Some text says ATM does NOT support CDP some say it does?
If someone enlighten me on this or refer to a decent documentatio on this topic, please. thanks Tariq
11-01-2006 05:47 PM
Tariq;
CDP runs on all media that support SNAP, including Ethernet, Frame Relay, and ATM physical media. CDP runs over the data link layer only. Therefore, two systems that support different network-layer protocols can learn about each other.
I would say the main reason SNAP is needed is because of the spread of different media that support it seems to be more of an interoperability issue.
11-01-2006 09:30 PM
Hi Adam
Many thanks for that. What I can see from some documents:
1) SNAP ecapsulation is what CDP frames are enveloped in. So if the configured connection such as Frame Relay can carry frame then CDP would work.
2) Not all models of ATM devices and all versions of IOS support CDP on ATM interfaces. It seems high end ATM routers with IOS 12.2 can support CDP.
Another question is if CDP is supported on SONET/SDH?
What I can't find is a more detailed document on CDP... Any ideas?
Thanks again.
11-02-2006 05:00 AM
of course there is the cisco provided info on CDP as linked below:
http://www.cisco.com/en/US/tech/tk648/tk362/tk100/tsd_technology_support_sub-protocol_home.html
here are a couple more links with the information displayed nicely:
11-05-2006 01:20 PM
Hi ,
CDP support is introduced in Cisco IOS Software Release 12.2(8)T. Currently, CDP is only supported on AAL5SNAP RFC 1483 PVCs and only on point-to-point subinterfaces. Multipoint subinterface support is not planned as yet.
Below link gives good example for ATM.
http://www.cisco.com/en/US/tech/tk39/tk48/technologies_q_and_a_item09186a008011a901.shtml#qa23
Thanks,
satish
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide