MPLS Path switch

[Wippe]

R1 can reach R4 through R2 and R3，R2 is the main path

When I turn off the direct interface between R2 and R1，always lose at least 8 packets。

I was used ISIS-BFD between R1 and R2,R1 and R3

LDP-IGP SYN is also used in R1 , R2 and R3

But nothing changed,what should i do to to reduce packet loss？

[M02@rt37]

Hello @Wippe 

Do you check BFD timers and verify that BFD sessions are up ?

LDP sessions are established ?

on ISIS process do you configure ?

mpls ldp sync

[Wippe]

Sure, use "bfd interval 999 min_rx 999 multiplier 5" and LDP sessions are established

[Wippe]

yeah，you are right

However, in the mpls area, as they are all IBGP, IGP is needed to control routing

[Wippe]

When I change the metrics of ISIS, there will be no packet loss

But when i shutdown the interface , there will be loss

Whats the problem?

[M02@rt37]

@Wippe 

When you change the ISIS metrics, it triggers a topology change, and the routers recalculate the routing table. This might be happening faster than when you manually shut down the interface. Check the convergence time after shutting down the interface.

[M02@rt37]

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[MHM Cisco World]

LDP-IGP SYN <<- this trick point can I see config of mpls igp syn