Re: PW to PSN tunnel mapping

[[e-mail]]

How to assign a particular PW to a particular tunnel is a local policy of
PE.

you can refer to the section 3.2.4 of
"draft-ietf-l2vpn-l2-framework-05.txt"

3.2.4. Tunnels

   A PW is carried in a "tunnel" from PE1 to PE2.  We assume that an
   arbitrary number of PWs may be carried in a single tunnel; the only
   requirement is that the PWs all terminate at PE2.

   We do not even require that all the PWs in the tunnel originate at
   PE1; the tunnels may be multipoint-to-point tunnels.  Nor do we
   require that all PWs between the same pair of PEs travel in the same
   tunnel.  All we require is that when a frame traveling through such a
   tunnel arrives at PE2, PE2 will be able to associate it with a
   particular PW.

   (While one can imagine tunneling techniques that only allow one PW
   per tunnel, they have evident scalability problems, and we do not
   consider them further.)

   There are a variety of different tunneling technologies which may be
   used for the PE-PE tunnels.  All that is really required is that the
   tunneling technologies allow the proper demultiplexing of the
   contained PWs.  The tunnels might be MPLS LSPs, L2TP tunnels, IPsec
   tunnels, MPLS-in-IP tunnels, etc.  Generally the tunneling technology
   will require the use of an encapsulation that contains a
   demultiplexor field, where the demultiplexor field is used to
   identify a particular PW. Procedures for setting up and maintaining
   the tunnels are not within the scope of this framework. (But see
   section 3.2.6, "Pseudowire Signaling".)

   If there are multiple tunnels from PE1 to PE2, it may be desirable to
   assign a particular PE1-PE2 PW to a particular tunnel based on some
   particular characteristics of the PW and/or the tunnel. For example,
   perhaps different tunnels are associated with different QoS
   characteristics, and different PWs require different QoS. Procedures
   for specifying how to assign PWs to tunnels are out of scope of the
   current framework.

   Though point-to-point PWs are bidirectional, the tunnels in which
   they travel need not be either bidirectional or point-to-point. For
   example, a point-to-point PW may travel within a unidirectional
   multipoint-to-point MPLS LSP.





> The draft-ietf-pwe3-control-protocol-08.txt mentions that the PW are set
> up to run inside a "PSN tunnel" and there is some talk about how this can
> happen by pushing an extra MPLS label etc. But there is nothing that says
> how a PE knows which PSN tunnel a PW belongs to? Is this supposed to be
> static configuration? Or is the assumption that there is only one PSN
> tunnel between two PEs - this would be a bad assumption since there would
> most likely be more than one PSN tunnel, with different QoS parameters.
>
>
> Benny Lønstrup Ammitzbøll, M.Sc.E.E.
> T|Pack A/S
> Lautrupbjerg 7-11
> DK-2750 Ballerup, Denmark
> Phone: [phone]
> Direct: ([phone]
> mailto:[e-mail] - www.tpack.net
>
(See attached file: winmail.dat)
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