The MPLS WG Archive

["Thomas D. Nadeau" <tnadeau@cisco.com>]

At 09:38 AM 4/16/2003 +0200, riza.cetin@alcatel.be wrote:

>"Thomas D. Nadeau" wrote:
>
> > >5. How can we represent label-stacking in LDP via this MIB. The
> > >label-stacking could be either
> > >- LDP LSPs over RSVP-TE tunnels.
> > >- PWE-LDP (Martini) LSPs over core LDP/RSVP - LSPs.
> > >
> > >Suggestion - Each core LSP (LDP/RSVP) can be represented by an if-index
> > >in the IF-MIB. If we include the if-index in the above tables then we
> > >can find out whether the LSP goes via a physical-interface or a
> > >'tunnel-interface'.
> >
> >          I don't understand how assigning an IfIndex to an LSP is going to
> > work.  This sounds like something that is implementation-specific.
>
>MPLS-TE MIB (draft-ietf-mpls-te-mib-09.txt) allows for defining an MPLS tunnel
>as an interface.
>mplsTunnelIsIf object is set to true(1) for tunnels to be used as interface
>and an entry is created in the ifTable with the ifIndex of the tunnel.
>
>Below is the text from the MPLS-TE-MIB.
>
>mplsTunnelEntry OBJECT-TYPE
>    SYNTAX        MplsTunnelEntry
>    MAX-ACCESS    not-accessible
>    STATUS        current
>    DESCRIPTION
>         "An entry in this table represents an MPLS tunnel.
>           An entry can be created by a network administrator
>           or by an SNMP agent as instructed by an MPLS
>           signalling protocol. Whenever a new entry is
>           created with mplsTunnelIsIf set to true(1), then a
>           corresponding entry is created in ifTable as well
>           (see RFC 2863). The ifType of this entry is
>           mplsTunnel(150)."
>
> >
> > The label stack is represented either in the LSR MIB as it is
> > defined today.  If you want to see the application-specific label,
> > then look in the PWE3 MIBs as a short-hand. The PPVPN-MPLS-VPN MIB is
> > also going to be modified to show the VPN label as well.  However,
> > in either case, the ingress labels should be available in the LSR MIB
> > as a point of reference.
> >
>
>How would you represent the tunneling LDP into RSVP-TE at the ingress LSR of
>the RSVP-TE tunnel?

         You would show the LSP in the LSR MIB being switched to
the TE label.

>Where would you store the labels (LDP label and RSVP label) that need to be
>pushed? In the label stack table of the LSR-MIB or higher layer.

         In the LSR MIB's XC table.  The question above asked how to do LDP/TE.
The forwarding/label stacking is different from the interface stacking
used to accomplish this. The ifStack looks like:

         Outgoing Interface:

         TE
         MPLS
         underlying layer (enet for instance)

         Incoming Interface:
         MPLS
         underlying layer (enet)

         The cross-connection on a switch to do this might be:

         Incoming LDP label, incoming interface -> NULL outgoing label

         NULL incoming label -> outgoing TE tunnel label, outgoing TE interface
                 XC defines a push with the incoming LDP label in the
                 label stack table.

         So the resulting outgoing label stack would be LDP label/TE label.
However, that would go out of the TE interface/MPLS interface.

         --tom


>Regards, Riza.
>
> >
> >          --Tom
> >
> > http://www.elsevier-international.com/catalogue/title.cfm?ISBN=155860751X


http://www.elsevier-international.com/catalogue/title.cfm?ISBN=155860751X