Re: Moving right along ... generalized-rsvp-te-05

["manoj juneja" <manojkumarjuneja@hotmail.com>]

Markus,
        I think first u have to create an FA between R1-OXC1-OXC2 with
switching type LSC. If u want to tunnel the packet traffic over this FA
-LSC LSP then u need to send another LSP request (Path message) with
switching type as PSC from R1 to OXC2. The path message will directly
be sent by R1 to OXC-2 (as R1 and OXC-2 are the end-points of the FA).
The OXC-2 will have to trigger new LSP from OXC-2 to R2 with switching
type PSC.

Lou, please correct me if I am wrong.

Regards,
manoj.


>From: Markus Jork <mjork@avici.com>
>To: Lou Berger <lberger@movaz.com>
>CC: ccamp@ops.ietf.org
>Subject: Re: Moving right along ... generalized-rsvp-te-05
>Date: Mon, 17 Dec 2001 16:39:18 -0500
>
>Lou,
>
>I think there is still some confusion in the draft regarding
>the switching type. Of course it could also be that the draft
>is perfectly clear and I'm confused...
>
>Quoting a response you gave to Manoj/Ben:
>
> > > >
> > > > >A Tunnel (FA) is a type
> > > > >    of link, not a class of switching.  This adds to the
> > > > >    confusion I've noted about the need for and use of Switching
> > > > >    Type.
> > >
> > >Switching Type continues to be ill-defined.  I have heard that the real
> > >definition is different from that given in the current drafts.  If the
> > >signaling information is not clearly defined and it's use described, we
> > >can hardly expect interoperability.
> >
> > I can't speak for others.  My belief is that there is a very concrete
> > definition.   I thought the text in the draft was clear as well, but let 
>me
> > try again:
> >
> >
> >          Switching Type: 8 bits
> >
> >          Indicates the type of switching that should be performed
> >          on a particular link.  This field is needed for links that
> >          advertise more than one type of switching capability.
> >          This field contains one of the values advertised for the
> >          corresponding link in the routing Switching Capability
> >          field as defined in [GMPLS-RTG].
> >
> > In other words, on links where one Switching Capability is advertised
> > (which will be all the time for most equipment) Switching Type is set to
> > the same value as advertised in routing.  On links where multiple 
>Switching
> > Capabilities are advertised, Switching Type is set to the value 
>advertised
> > in Switching Capability that matches the type of switching to be 
>performed.
> >
> > [I'll put the revised text in the next rev...]
> >
>
>Let's look at the example of two IP routers connected to a cloud of
>opaque OXCs:
>
>R1 ----- OXC1 ----- OXC2 ----- R2
>     LSC        LSC        PSC
>
>OXC1 and OXC2 switch the Sonet stream from an incoming interface to
>some outgoing interface, that's why links R1-OXC1 and OXC1-OCX2
>are advertised as LSC in the IGP. Link OXC2-R2 is PSC because R2 looks
>at the incoming IP packets. The encoding on the links is OC192.
>
>Now I want to setup an LSP between R1 and R2. (This LSP is essentially
>a "lightpath" through the optical cloud and will be advertised as FA
>so that PSC LSPs can be tunneled through it later.)
>What is the switching type requested in the Generalized Label Request
>object? I would expect LSC.
>But section 2.1 of draft-ietf-mpls-generalized-rsvp-te-06 says:
>
>    A Generalized Label Request object is set by the ingress node,
>    transparently passed by transit nodes, and used by the egress node.
>
>This would suggest the switching type needs to be PSC.
>But then the text in 2.1.1 says:
>
>    Nodes MUST verify that the type indicated in the Switching Type
>    parameter is supported on the corresponding incoming interface.  If
>    the type cannot be supported, the node MUST generate a PathErr
>    message with a "Routing problem/Switching Type" indication.
>
>So when the Path message requested PSC, it would be rejected by OXC1
>and OXC2. When it requested LSC it would be rejected by R2.
>The transit nodes can't modify the switching type in the Path message
>because they don't have enough knowledge to pick the right one.
>How is this supposed to work?
>
>thanks for any clarification,
>Markus
>
>
>


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