The MPLS WG Archive

[Thomas Nadeau <tnadeau@cisco.com>]

        Lets first be specific about which document
we are referring to. It sounds like you are referring to
the MPLS-TE-MIB. If you are, then read on, otherwise
skip my reply.

> Here is my question:
> When you create a tunnel at the head-end, you can set the
> mplsTunnelIsIf
> variable to TRUE and this specifies that an interface will be created
> over
> the tunnel at the head-end.

        

Not
really. This means that the tunnel IS the ifIndex associated
with it.

> What is the procedure for
> identifying at the
> tail-end that this tunnel is to be used as an interface (for the purpose
> of
> receiving packets coming from the head-end)?.

        

First,
note that this functionality is optional in the MIB. Second,
this can be implemented only if your device creates an tunnel entry
at
the egress. Note that this will be at the penultimate-hop, if that is
enabled.

> Should a tail-end manual entry be
> made in the TE table ahead of time with
> the mplsTunnelIsIf value set to TRUE?.

        

Depends on
your implementation. I suppose that you could manually
create such an entry, but I am not sure why. Some implementations
represent
the tail of the tunnel the same way that other midpoints are represented
(without 
an ifIndex) except that the tunnelRole would be set to
tail(3).

> If so, it does not seem like
> there is
> a (documented) way to uniquely identify an incoming signalling message
> (for
> tunnel termination) using the tail-end TE MIB specification. In other
> words
> how do I match a user created tail-end configuration with (say) a
> RSVP
> session that is terminating on this tail-end
> LSR.

        

You should
be able to figure this out given the RSVP-TE information
stored at the tail-end router. It should tell you that this RSVP-TE
session 
terminates at that LSR the same way that a mid-point LSR tells 
keeps
information about transit-sessions.

        

--Tom

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Mathematics is the supreme nostalgia of our time.