Tuning the MPLS Traffic-engineering Reoptimization Timers

-Referring to the previous configuration, tunnel 1 preferred path is R1>R4>R2.


R1#show mpls traffic-eng tunnels tunnel 1

Name: R1_t1                               (Tunnel1) Destination: 2.2.2.2
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected

    path option 10, type explicit R1-R4-R2 (Basis for Setup, path weight 2)
    path option 20, type dynamic

    RSVP Path Info:
      My Address: 192.168.14.1
      Explicit Route: 192.168.14.4 192.168.24.4 192.168.24.2 2.2.2.2


-If one of the link along the path of R1>R4>R2 is down, the preferred path will be R1>R2.

R1(config)#int fa0/1
R1(config-if)#shutdown

R1#show mpls traffic-eng tunnels tunnel 1

Name: R1_t1                               (Tunnel1) Destination: 2.2.2.2
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected

    path option 20, type dynamic (Basis for Setup, path weight 10)
    path option 10, type explicit R1-R4-R2

   Shortest Unconstrained Path Info:
    Path Weight: 10 (TE)
    Explicit Route: 192.168.12.1 192.168.12.2 2.2.2.2


-When the failed link comes back online, the tunnel is not using the preferred path R1>R4>R2 immediately though the shortest constraint path is R1>R4>R2 due to the default timer to re-optimize the tunnel is being 3600 seconds which is 1 hour.

R1(config)#int fastEthernet 0/1
R1(config-if)#no sh

R1#show mpls traffic-eng tunnels tunnel 1

Name: R1_t1                               (Tunnel1) Destination: 2.2.2.2
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected

    path option 20, type dynamic (Basis for Setup, path weight 10)
    path option 10, type explicit R1-R4-R2

     RSVP Path Info:
      My Address: 192.168.12.1
      Explicit Route: 192.168.12.2 2.2.2.2
 
  Shortest Unconstrained Path Info:
    Path Weight: 2 (TE)
    Explicit Route: 192.168.14.1 192.168.14.4 192.168.24.4 192.168.24.2                    2.2.2.2

  -Let's configure the tunnel to re-optimize every 30 seconds. After 30 seconds, the tunnel will be using back the preferred path R1>R4>R2.

 R1(config)#mpls traffic-eng reoptimize timers frequency 30

R1#show mpls traffic-eng tunnels tunnel 1

Name: R1_t1                               (Tunnel1) Destination: 2.2.2.2
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected

    path option 10, type explicit R1-R4-R2 (Basis for Setup, path weight 2)
    path option 20, type dynamic

    RSVP Path Info:
      My Address: 192.168.14.1
      Explicit Route: 192.168.14.4 192.168.24.4 192.168.24.2 2.2.2.2
   
  Shortest Unconstrained Path Info:
    Path Weight: 2 (TE)
    Explicit Route: 192.168.14.1 192.168.14.4 192.168.24.4 192.168.24.2
                    2.2.2.2