Link Layer Discovery Protocol

We have had some conversations lately over the use of link layer protocols to discover the local network topology. Specifically, some of our devices attempt to identify their neighbors using Cisco Discovery Protocol (CDP). Other devices do not understand the protocol and propagate these link layer packets. Depending on the size of the network, this may be causing problems. It turns out that we are not the only ones to have this issue and the industry has been addressing the issue by standardizing a Link Layer Discover Protocol (LLDP) in IEEE 802.1AB. In addition, the Telecommunications Industry Association (TIA) has created an enhancement called Media Endpoint Discovery. This enhancement addresses Voice over IP (VoIP) deployment and troubleshooting issues.

References

A. Bierman and K. Jones, ‘Physical Topology MIB’, The Internet Engineering Task Force Request For Comments Repository (September 2000) <http://www.ietf.org/rfc/rfc2922.txt> [accessed Tuesday, April 3, 2007]

IEEE Computer Society LAN/MAN Standards Committee, ‘IEEE Std 802.1AB^TM-2005 — Station and Media Access Control Connectivity Discovery’, IEEE Standard for Local and metropolitan area networks (6 May 2005) <http://standards.ieee.org/getieee802/download/802.1AB-2005.pdf> [accessed Tuesday, April 3, 2007]

Telecommunications Industry Association, ‘Link Layer Discovery Protocol for Media Endpoint Devices’, TIA Standards, Telecommunications, IP Telephony Infrastructure (April 6, 2006) <http://www.tiaonline.org/standards/technology/voip/documents/ANSI-TIA-1057_final_for_publication.pdf> [accessed Tuesday, April 3, 2007]

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