Re: Multi-AS needs : draft-zhang-mpls-interas-te-req-02.txt

Kenji Kumaki wrote:
> 
> I think the latter is correct.
> We need to extend a existing protocol(e.g. RSVP-TE) because a current
> RSVP-TE can't cover an inter-AS TE.

What makes you say that?

I don't think current implementations can support this.  But RFC 3209 
includes inter-AS provisions.

See section 7.4.

One of the EXPLICIT_ROUTE subtypes is an AS number.  If one of these is 
present in an EXPLICIT_ROUTE object, then the abstract node represented 
is the entirity of the specified ASN.

Implementations should treat this in a similar fashion to how they treat 
an IP subnet ERO subobejct.  If it's the first subobject, then the 
router must be in that ASN.  If it's the subobject corresponding to the 
next-hop, then it should use that ASN to determine the next hop along 
the path to that ASN.  If the node is strict, then the next-hop address 
should be a part of that ASN.

I'm not sure if BGP provides sufficient information for generating a 
topology of ASNs (needed for generating an AS-hop-path).  An extension 
of some form might be necessary for this to work.  But that would be a 
routing extension, not an RSVP extension.  And it would only be 
necessary if you want to dynamically generate inter-AS explicit routes - 
a feature of dubious utility to begin with.

-- David