Subject: RE: draft-gan-fast-reroute

From: "David Allan" <[email-masked]>
Date: Thu, 18 Oct 2001 09:45:54 -0400

OK, so that has some utility. If specify my service requirement in the TSpec
and the Adspec and that is what is echoed in the flow spec, then presumably
that becomes the MTU size to which detour MTUs would be compared and I will
not chuck perfectly good detours simply because they have a smaller MTU than
some large number I don't need anyway.
 
Now if the service requirement is very close or equal to the path, creating
a viable protected path becomes very hit or miss. So we need a different
dimension of "over-engineering" ;-)
 
Dave
 
-----Original Message-----
From: Sundara Murugan [mailto:[email-masked]]
Sent: Wednesday, October 17, 2001 7:20 PM
To: Allan, David [CAR:NS00:EXCH]; Sundara Murugan; 'Arthi Ayyangar ';
[email-masked] '
Cc: 'Alia Atlas '; [email-masked] '
Subject: RE: draft-gan-fast-reroute

Dave,
    You can request the MTU size you want by specifying it in the TSpec and
in the Adspec. Routers along the path update the Adspec MTU if its interface
MTU is lower than the received Adspec MTU.
 
When the Path message reaches the egress, the egress will know the MTU size
than can be supported by all the routers along the path. Then It can specify
this MTU in the flow spec. When the resv message reaches the ingress it can
either accept the resv or deny it.
 
-sundara

-----Original Message-----
From: David Allan [mailto:[email-masked]]
Sent: Friday, October 12, 2001 1:13 PM
To: Sundara Murugan; 'Arthi Ayyangar '; [email-masked] '
Cc: 'Alia Atlas '; [email-masked] '
Subject: RE: draft-gan-fast-reroute

Sundara: 

If the detour MTU must be >= the main LSP MTU, how is this achieved? If I
understand the protocol flows correctly, you only know what you got, you
cannot request a specific MTU. So there is not a method to easily find a
useful detour, and does this not disqualify perfectly good detour
opportunities when the RESV MTU for the main path exceeds the service
requirement?

thanks 
Dave