Routing

Hello,

We are running large MPLS network with the label distribution protocol being LDP. I want to have RSVP based link protection on a sinlge link on the network. Could I build a RSVP LSP between the directly adjacent routers, tunnel LDP over it and protect the RSVP LSP? The topology I am considering is:

 _____                     _____
|     |  <---RSVP LSP---> |     | 
| R2  |-------------------| R1  |
|_____|                   |_____|
    \			    /
     \	                   /
      \ _____	     _____/
       |     |      |     |
       | R4  |------| R3  |
       |_____|      |_____|
           

 The bypass LSP will go via R1-R3-R4-R2. Will this work? In event of the link between R1-R2 going down, will the LDP between R1 and R2 stay up? Will the transit MPLS traffic crossing R1 and R2 be protected and preprogrammed in the PFE?

Sure!

For example rsvp fast-reroute with per flow load balancing (preprogram pfe)will do the trick. When LSP ldp tunneling is enabled LDP session(control path) is targeted ( b/w endpoints loopback addr) and shouldn't be affected by link failure. Data path will switch over detour LSP in miliseconds.

Krasi

Thanks Krasi. I am considering running this solution throughout the whole network. We have around 50 nodes all running LDP. I want to add the fast-reroute capability but keep the LDP. So, I plan to run RSVP LSPs only between the directly connected notes and tunnel LDP on top of it without having fill mesh RSVP between all notes. Do you see any possible issues with this ?

That is one of the recommended solutions(<50ms protection) for large N^2 rsvp full mesh scaling. 

Krasi