10-08-2005 08:21 PM
Folks,
Can someone send me a documentation that explains the main difference between LDP and TDP.
After what version of IOS did cisco start implementing LDP as the default label distribution protocol?
How do i convert from TDP to LDP?
Can TDP and LDP coexist?
Thanks
10-10-2005 04:36 AM
LDP is quite similar to TDP.
LDP is standardized by IETF
LDP has more features such as abort, MD5 authentication, notification, backoff logic etc.
TDP is the default on Cisco routers
LDP is the default with this global config -
mpls ldp protocol ldp
LDP/TDP operates in three steps -
Neighbor Discovery
Session establishment
Label Distribution/exchange
Once labels are exchanged, LIB is built
LIB and FIB together helps to build LFIB
TDP Neighbors are discovered via TDP Hellos (like most of the routing protocols)
TDP Hellos are sent to 255.255.255.255
TDP hellos are sent to UDP port = 711
TDP hellos are sent only after mpls ip is configured on an interface
LDP Neighbors are discovered via LDP Hellos (like most of the routing protocols)
LDP Hellos are sent to 224.0.0.2
LDP hellos are sent to UDP port = 646
LDP hellos are sent only after both mpls ip and mpls label protocol ldp are configured on an interface ** unless you have the global command in.
and yes ldp and tdp can coexist but you cannot mix them on an interface i.e. R1 s1/0 connects to R2 s2/0. In this scenario you MUST have either LDP or TDP on each interface, otherwise they will not for a neighbourship.
10-10-2005 07:50 AM
Robert,
Good summary. Just a few clarifications.
- The default has been changed to LDP in 12.4, 12.4T and 12.2S.
- "mpls label protocol both" can be used on multi-access links where neighbors might be running a different protocols.
- TCP port 646 and 711 are also respectively used by LDP and TDP for the purpose of label information exchange.
Hope this helps,
10-10-2005 11:37 PM
cheers H didnt know about the "both" command, although in my environment i dont need it - all links are p-t-p. But I can see where I might need this :-)
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