MPLS TE path preemption

hello,everybody. i'd like to ask is there any preemption mechanism among TE path

say if you have a tunnel with 2 paths : dynamic and explicit.. Explicit is used first. when link is down in the network,dynamic is used.

but what if that link comes up again.. how the originally selected explicit path can be preempted back automatically. Is that possible?

i mean not creating another tunnels,or using fast-reroute option..

 

 

 

 

regards,

Nizami

Comments



  • Re: [CCIE SP] MPLS TE path preemption


    MPLS Traffic-eng priority command will fix that and adjust the TE timers in global





    On 3/18/09 7:26 PM, "nizami" <[email protected]> wrote:



    hello,everybody. i'd like to ask is there any preemption mechanism among TE path



    say if you have a tunnel with 2 paths : dynamic and explicit.. Explicit is used first. when link is down in the network,dynamic is used.



    but what if that link comes up again.. how the originally selected explicit path can be preempted back automatically. Is that possible?



     



     



     



     



    regards,



    Nizami









    Internetwork Expert - The Industry Leader in CCIE Preparation

    http://www.internetworkexpert.com



    Subscription information may be found at:

    http://www.ieoc.com/forums/ForumSubscriptions.aspx



  • priority is for comparing several tunnels,but i need comparison among paths on the same tunnel.

  • Within tunnel interface the path-option with lowest number (valid path) will be selected first.

    preempt will be done with 'mpls traffic-eng reoptimize' manually or configured by timers

    Below: two samples with three valid path-options. Lowest number always selected

    Jon

    ******************************************************************

    interface Tunnel10
     ip unnumbered Loopback0
     mpls ip
     tunnel destination 124.1.4.4
     tunnel mode mpls traffic-eng
     tunnel mpls traffic-eng autoroute announce
     tunnel mpls traffic-eng priority 7 7
     tunnel mpls traffic-eng bandwidth  2500
     tunnel mpls traffic-eng path-option 5 explicit name TE_1
     tunnel mpls traffic-eng path-option 8 dynamic
     tunnel mpls traffic-eng path-option 10 explicit name TE_2


    SPRack1R1#sh mpl tr tunnels

    Name: SPRack1R1_t10                       (Tunnel10) Destination: 124.1.4.4
      Status:
        Admin: up         Oper: up     Path: valid       Signalling: connected

        path option 5, type explicit TE_1 (Basis for Setup, path weight 160)
        path option 8, type dynamic
        path option 10, type explicit TE_2w

    ***************************************************************************'
    interface Tunnel10
     ip unnumbered Loopback0
     mpls ip
     tunnel destination 124.1.4.4
     tunnel mode mpls traffic-eng
     tunnel mpls traffic-eng autoroute announce
     tunnel mpls traffic-eng priority 7 7
     tunnel mpls traffic-eng bandwidth  2500
     tunnel mpls traffic-eng path-option 2 dynamic
     tunnel mpls traffic-eng path-option 5 explicit name TE_1
     tunnel mpls traffic-eng path-option 10 explicit name TE_2


    SPRack1R1#sh mpl tr tunnels

    Name: SPRack1R1_t10                       (Tunnel10) Destination: 124.1.4.4
      Status:
        Admin: up         Oper: up     Path: valid       Signalling: connected

        path option 2, type dynamic (Basis for Setup, path weight 12)
        path option 5, type explicit TE_1
        path option 10, type explicit TE_2

     












  • There's not really an automatic preemption.  But you can use the
    reoptimization timers to speed that up.  By default, tunnely are checked every
    hour (3600 seconds).

     

    Scott

     

    From: [email protected]
    [mailto:[email protected]] On Behalf Of nizami

    Sent: Wednesday, March 18, 2009 1:26 PM

    To: [email protected]

    Subject: [CCIE SP] MPLS TE path preemption

     

    hello,everybody. i'd like to ask is there any preemption mechanism among TE
    path

    say if you have a tunnel with 2 paths : dynamic and explicit.. Explicit is
    used first. when link is down in the network,dynamic is used.

    but what if that link comes up again.. how the originally selected explicit
    path can be preempted back automatically. Is that possible?

     

     

     

     

    regards,

    Nizami







    Internetwork Expert - The Industry Leader in CCIE Preparation

    http://www.internetworkexpert.com



    Subscription information may be found at:

    http://www.ieoc.com/forums/ForumSubscriptions.aspx
















  • There's not really an automatic preemption.  But you can use the
    reoptimization timers to speed that up.  By default, tunnely are checked every
    hour (3600 seconds).

     

    Scott

     

    From: [email protected]
    [mailto:[email protected]] On Behalf Of nizami

    Sent: Wednesday, March 18, 2009 1:26 PM

    To: [email protected]

    Subject: [CCIE SP] MPLS TE path preemption

     

    hello,everybody. i'd like to ask is there any preemption mechanism among TE
    path

    say if you have a tunnel with 2 paths : dynamic and explicit.. Explicit is
    used first. when link is down in the network,dynamic is used.

    but what if that link comes up again.. how the originally selected explicit
    path can be preempted back automatically. Is that possible?

     

     

     

     

    regards,

    Nizami







    Internetwork Expert - The Industry Leader in CCIE Preparation

    http://www.internetworkexpert.com



    Subscription information may be found at:

    http://www.ieoc.com/forums/ForumSubscriptions.aspx





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