Difference between LDP and TDP anyone?

[NAVIN PARWAL]

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

[romccallum]

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.

[Harold Ritter]

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,

[romccallum]

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 :-)