[mpls-linux-general] ldp_linux add route question

[Igor V. <ch...@fl...>]

Hello all,

Consider this setup:

LER2------LSR1-------LER1

Let's assume LER2 is the egress for FEC1.
LSR1's IP routing table contains FEC1, (with LER2 as a gw).

LDP session establishes between LER2 and LSR1, and LER2 transmits a label
for FEC1 to LSR1.

Now, inside ldp_linux daemon on LSR1, I type

prompt>add route FEC1/32  LER1

How does LDP consider this now:
a) LER2 is no longer next hop for FEC1, LER1 is the new next hop for FEC1
b) LER1 and LER2 are both valid next hops for FEC1

?

I tested this setup. If LER1 is also the egress for FEC1, and LDP session
establishes between LER1 and LSR1, I get 2 labels for the same FEC on LSR1.
I tested this in conservative retention mode, but I'm uncertain how ldp
understands the "add route" inside the daemon. If a) is the case, then LSR1
should issue a label release message for the FEC, which it does not.

Thanks in advance,

Igor Vukomanovic