RE: TE metric and graceful restart

[Zafar Ali <zali@cisco.com>]

At 03:12 PM 4/26/2002 -0400, Don Fedyk wrote:

> Yakov 
>
> I have a question. Do you mean that a node that is
> restarting 
> its routing view and learning from it's neighbors
> should mark 
> the TE metrics to local neighbors to infinity?

Dear Dan, Yakov, et all:

One point that I would like to point out and make sure that it is NOT a
requirement that a restarting node SHOULD advertise the infinity TE
metric, 0 bandwidth attributes, etc. 

The reason that I understood this as a MAY case is that a node
that saves bandwidth usage state information locally is able to determine
(or estimate) the amount of unreserved resources immediately upon
start-up. In which case it MAY advertise the saved (projected)
value(s) during the graceful restart period. Understood that in doing so
the node in question looses the charm of discouraging other nodes in the
network in using it, during the restart period, but this should be a
local decision. Furthermore, after completion of the restart procedure,
the node in question may only re-advertise the actual account information
if there is a significant change between the projected values and the
actual value computed as part of the recovery procedure. Hence, in this
fashion, it minimizes the disruption to the network. 

Please verify. 

Thanks

Regards... Zafar 

> I think that during
> any graceful restart the TE metrics will not have a
> perfect view 
> and local path selections should be blocked but
> setting the metrics 
> artificially to infinity seems like the wrong way to
> do this in my 
> opinion. 
>
> Don 
>
> > -----Original Message-----
> > From: Alex Zinin
> [mailto:zinin@psg.com]
> > Sent: Friday, April 26, 2002 2:55
> PM 
> > To: Yakov Rekhter 
> > Cc: ccamp@ops.ietf.org 
> > Subject: Re: TE metric and graceful
> restart 
> > 
> > 
> > Yakov, 
> > 
> >   How does this improve the situation
> given that 
> >   unreserved BW of 0 is already
> announced? 
> > 
> > -- 
> > Alex 
> > 
> > Thursday, April 25, 2002, 12:47:57 PM, you
> wrote: 
> > > Folks, 
> > 
> > > It was suggested to set the TE metric to
> infinity during graceful 
> > > restart (both for ISIS and OSPF).
> > 
> > > Any objections to this suggestion
> ??? 
> > 
> > > Yakov. 
> > 
> > 
> >
===============
Zafar Ali
Cisco Systems
(734) 276-2459
100 S Main St. #200
Ann Arbor, MI 48104.
email: zali@cisco.com