The MPLS WG Archive

["Ashwin C. Prabhu" <Ashwinp@in.huawei.com>]

Title: RE: non-RSVP routers.

Hi

 I don't think IGP LSA's have any such field which
 tells signalling protocol is enabled or not.
 ( Note that it can even be LDP not necessarly RSVPTE )

Ashwin

-----Original Message-----
From: Gopinath G - CTD, Chennai. [mailto:gopinathg@ctd.hcltech.com]
Sent: Tuesday, February 05, 2002 10:40 AM
To: mpls@UU.NET
Subject: RE: non-RSVP routers.

Hello,

    I hope LSA's of IGP may help to find the next hop is RSVP capable or
not...

pls corect me  if I am wrong

gopinathg

-----Original Message-----
From: schultz@io.iol.unh.edu [mailto:schultz@io.iol.unh.edu]
Sent: Saturday, February 02, 2002 11:53 PM
To: Subhakar K S
Cc: mpls@UU.NET
Subject: Re: non-RSVP routers.

Hello,

Please see the last paragraph in RFC 2205, section 3.8:

"With normal IP forwarding, RSVP can detect a non-RSVP hop by comparing
the IP TTL with which a Path message is sent to the TTL with which it is
received; for this purpose, the transmission TTL is placed in the common
header.  However, the TTL is not always a reliable indicator of non-RSVP
hops, and other means must sometimes be used.  For example, if the routing
protocol uses IP encapsulating tunnels, then the routing protocol must
inform RSVP when non-RSVP hops are included.  If no automatic mechanism
will work, manual configuration will be required."

However, RSVP-TE will not work with non-RSVP routers.  Please see section
4.2.5 of RFC 3209.

Thanks,
-Ben

On Fri, 1 Feb 2002, Subhakar K S wrote:

>
> How does an intermediate router finds if its
> downstream router is RSVP aware or not.
>
>
> thanks,
> S.
>
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