Wednesday, April 7, 2021

Path Selection algorithm in show route protocol rsvp (inet.3 table)

Hello guys,

I have a network with Juniper vMX running MPLS (RSVP-TE is used) and we set up 2xlsp paths between the same head end and tail end routers. The CSPF metric and the reserved bandwith are different between the 2 LSPs. I see that in the inet.3 table both of them take the lowest IGP metric to reach the destination but I am not sure I understand what is the algorithm behind which route is actually selected (the arrow points to interface-2 although lsp2 seems to have higher cspf metric). Is there any logic behind which of the lsp is chosen in this case? It always chooses the lsp2 here even though it seems to have lower bandwidth and higher cspf metric. What is the arrow actually indicating in this case since it does not seem to be the best path?

The CSPF for lsp1 is 100 and for lsp2 is 200. The res. Bandwith for lsp1 is 1000m and for lsp2 is 1m.

Strangely if I change the lsp2 to 10m the arrow switches to lsp1.....

I have an inquiry related to the selection of the best path in the show route protocol rsvp output:

>show route protocol rsvp destination 1.1.1.1:

inet.3: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)

+ = Active Route, - = Last Active, * = Both

1.1.1.1 *[RSVP/7/1] 00:10:16, metric 100

via interface-1, label-switched-path lsp1

>via interface-2, label-switched-path lsp2



No comments:

Post a Comment