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Forum Replies

  1. milan9 says:

    Great as always. Just one minor issue. On the first topology picture, shouldnt the provider AS number be 123 as you stated in text instead of AS 234 or vice versa?

  2. Marek,
    This topic can become less confusing if you think about what is going on in the control plane vs the data plane. The RTs are used in the control plane to associate ROUTES with VRFs. The VPN label is used in the data plane to associate PACKETS with VRFs.

    Check out this great article that talks about why RDs, RTs, and VPN Labels are all needed:

  3. Hello Mohammad

    An excellent and very in depth explanation of how traceroute and MPLS function can be found in this Cisco documentation. It includes information about the elements found within the frame headers and how these are translated and outputted in the traceroute output as label values.

    I hope this has been helpful!


  4. Hi Rene,
    Please see the bold output below …

    CE1#traceroute source loopback 0
    Type escape sequence to abort.
    Tracing the route to
    VRF info: (vrf in name/id, vrf out name/id)
      1 0 msec 0 msec 4 msec
      2 [MPLS: Labels 17/19 Exp 0] 0 msec 0 msec 4 msec
      **3 [MPLS: Label 19 Exp 0] 0 msec 0 msec 4 msec**
      4 0 msec 0 msec *

    why its showing instead of . As we know it should show exit interface IP . Is there logic behind this ??? Please make me clear .Thx


  5. Hello Mohammad.

    Hmm, that may be a typo. I will get @ReneMolenaar to look at that…



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