mpls session

[Just Kennie]

london#show mpls ldp parameters

Protocol version: 1

Downstream label generic region: min label: 16; max label: 100000

Session hold time: 180 sec; keep alive interval: 60 sec

Discovery hello: holdtime: 15 sec; interval: 5 sec

Discovery targeted hello: holdtime: 90 sec; interval: 10 sec

Downstream on Demand max hop count: 255

LDP for targeted sessions

LDP initial/maximum backoff: 15/120 sec

LDP loop detection: off

-----whats the difference and effect of the below timers..

Session hold time: 180 sec; keep alive interval: 60 sec

Discovery hello: holdtime: 15 sec; interval: 5 sec

Discovery targeted hello: holdtime: 90 sec; interval: 10 sec

[Giuseppe Larosa]

Hello Kennie,

LDP uses UDP port 646 for discovery sending packets with a multicast destination and a source = LDP router-id and a destination 224.0.0.2 with TTL=1.

They are used to discover possible neighbors.

use sh mpls ldp discovery to check the state of LDP sessions.

so discovery timers applies to UDP

session parameters are for the TCP sessions built on port TCP 646.

Label exchange happens on TCP sessions.

targeted sessions are another type of session between non adjacent nodes (example EoMPLS )

the LDP router-id has to be advertised in the IGP in use.

The IGP has to be classless.

Hope to help

Giuseppe