The MPLS WG Archive

[Gaitonde Anandprasanna <prasanna@csa.iisc.ernet.in>]

Thanx for answering my queries to all.

I have one more query . Please see below


On Mon, 4 Dec 2000, David Charlap wrote:

> venkir@samsung.co.kr wrote:
> > 
> >         You r correct only, i.e., the first option is corect.
> > Actually, in that paragraph, they explained about two scenarios. First 
> > one is about non-rsvp node as downstream router.  In that case,
> > upstream router has to send patherr. It's fine. Second one dealing
> > with the case, where non-rsvp node as upstream router. That means if a
> > rsvp node, gets a path message with LABEL_REQUEST from a non-rsvp
> > node,  it has to send a patherr message.  Here message is from a
> > non-rsvp node. Am I right?
> >         But only thing is, how come, a non-rsvp node sends a path
> > message with LABEL_REQUEST to rsvp node? I don't think, this case will
> > arise in real time scenario.
> 
> The non-RSVP node won't generate such a message - it's not running RSVP!
> 

Thats correct.

> But it will forward such a message if it receives it.  The PHOP node
> doesn't necessarily know that there's a non-RSVP router between it and
> the next hop.  It may generate a Path message with LABEL_REQUEST, not
> knowing that there's a non-RSVP router present on that link.  The
> non-RSVP router then forwards the message.
> 

Yes, But can a PHOP node know wether the node ahead of it is RSVP capable
or not. Is there any way ?? Please let me know..


> The NHOP RSVP router that receives the message detects the non-RSVP
> router (by comparing TTL values), sees that there's a LABEL_REQUEST
> object (indicating that this is an RSVP-TE Path message and not a non-TE
> message), and proceeds to drop the message and generate a PathErr.
> 

Yes this clear to me now..
Thanx a lot.


Pras





> -- David
> 


                 
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