Tunnel Modes

So far, you've seen two independent questions:

  • How is the queuing indicator (IP Precedence or MPLS EXP) propagated up and down the label stack and upon exit from the MPLS network?

  • In the mpls2mpls and mpls2ip pop cases, which PHB does the resulting packet get?

This section covers reasons why you might want to enforce different behaviors, as well as the mechanisms being defined to standardize those behaviors.

Currently, a set of behaviors are being defined that give you a set of mechanisms to control EXP values in various scenarios. These mechanisms are called tunnel modes. Three tunnel modes are defined in RFC 3270:

  • Uniform

  • Short-Pipe

  • Pipe

These modes are defined in the same IETF draft that defines L-LSP—“MPLS Support of Differentiated ...

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