The MPLS WG Archive

[Thomas Nadeau <tnadeau@cisco.com>]

I think you misunderstood, the actual value of the ifIndex is of no consequence,

you just have to have a corresponding interface at the other end.

        Okay, so what is the problem then? 8)

 

The problem is that the TE MIB does not provide *complete* configuration support for setting up of a "corresponding" tail-end tunnel interface.

        

What you
don't find in there today is an example of how to do this, but it
certainly
does allow for this type of configuration (see below).

On the head-end it provides all of the required configuration parameters (isIf, name) and on the tail-end it provides some (isIf, name) but not all (you would at least need the head-end tunnel index to be specified at the tail-end).

Let me try the question again in case my earlier questions were not clear.

If I create a tunnel  interface on a head-end router and would like to create a corresponding tail-end tunnel interface on the tail-end router, how do I do this using the TE MIB.

        

Your
implementation should keep some sort of RSVP-TE record at the
tail end of the router. Your MPLS-TE-MIB agent can then use this
information
to create a tunnel entry for it. The agent can then assign an ifIndex to
this entry.
The indexes will be the same as at the head end, so your NMS can 
correlate them that way. You can optionally allow the operator to
assign
the ifIndex. Note that the operator could also do this at the head as
well.

I would like to see a complete solution using just the TE MIB

(because it attempts to solve the problem on the head-end),

        

This is
not the case. The MIB allows for the configuration of the head, midpoints
and tail -- wherever your implementation supports it.

if this is not possible then what other MIB tables should I use and how?. I can easily come up with some proprietary scheme to do this but I would like to see some "standard" usage guidelines.

        

Well, to
be honest with you, your implementation and one other are the only
ones that I have heard use this scheme of two ifIndexes for a tunnel. All
of the 
others I know of (about 30 or so), create a single configuration record
at the head
end where a corresponding tunnelEntry is created. Most also bound an
ifIndex to the 
tunnelEntry at that time. Some optionally create entries at midpoints and
the tail, but 
without ifIndexes at either of these places.

 Again, given that the TE MIB seems to be taking on the responsibility of creating tunnel interfaces

        

For
reference, the MPLS TE MIB does NOT require that an ifIndex be assigned
anywhere.  The MIB assumes that the agent (or operator) creates the
tunnel interface(s) 
where necessary; the MIB cannot create anything per se. If you do create
an entry and have
a corresponding ifIndex, then the tunnelIsIfIndex is used to indicate
this. If you want to 
assign an ifIndex at the tail, they go for it, but remember to turn this
bit on so that operators
and NMS systems know that a corresponding Interfaces MIB entry exists
and
can be examined.

I would like a "standard" way of doing it on the tail-end to be documented in the mpls-te-mib specification.

        

The MIB
shows examples of how it is commonly used. If you would like an
additional
example at this point, I think that you just volunteered to write
something up. 8)

        

--Tom

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