MPLS Label

Hi Guys,


I am watching Brian CCIE SP video and following his practical on my pc in dynamips.

From R8 when I do the trace the router is showing the MPLS lable even though this router is not running mpls

Please guide

3600 Software (C3640-JK9S-M), Version 12.4(16), RELEASE SOFTWARE (fc1)




Type escape sequence to abort.

Tracing the route to


  1 36 msec 32 msec 8 msec

  2 [MPLS: Label 26 Exp 0] 44 msec 8 msec 24 msec

  3 [MPLS: Label 26 Exp 0] 16 msec 32 msec 24 msec

  4 [MPLS: Label 27 Exp 0] 20 msec 20 msec 20 msec

  5 20 msec *  68 msec




When I enabled CellModeATM and confiured my R1 and R2 and tried to trace from R3 the loopback of R2 my CellModeATM is not hidden in trace, why? please help




Type escape sequence to abort.

Tracing the route to


  1 [MPLS: Label 25 Exp 0] 68 msec 20 msec 52 msec

  2 [MPLS: Label 0 Exp 0] 16 msec 16 msec 64 msec

  3 16 msec *  72 msec





  • Try disabling mpls ip ttl-expiration in your core where you are running MPLS.


    Thank you,



  • Hi Miguel,

    Thanks for the reply, I do not want to disable the mpls ttl-expiration in my core, by default router 8 is not running mpls so my understanding is whin I do the traceroute from router 8 it should not show me the mpls label.




  • No matters if you use MPLS or not.

    If a packet goes from router that is not MPLS enabled and traverses through MPLS path

    toward destination it will have labels imposed & same will be shown in traceroute.

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