From: Eric Hill (eric_at_[hidden])
Date: 2007-06-06 10:49:27
I have been requested to write a tiny diagnostic application that will
listen for Cisco Discovery Protocol (CDP) messages from Cisco switches on
a workstation so that the workstation will "know" what switch port it is
plugged into. I have found the following information with my limited
google-foo:
CDP Packet Format:
http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm#xtocid12
CDP Information:
http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a0080094713.shtml#cdp
The latter link says that CDP uses a destination multicast address
01-00-0c-cc-cc-cc, HDLC protocol type 0x2000 on an Ethernet segment. This
is where I get lost. Is that an Ethernet MAC broadcast, or a socket-based
broadcast? Can I capture those CDP advertisements with asio?
Eric