Subject: Re: MED

From: "Reinaldo Penno Filho" <[email-masked]>
Date: Fri, 12 Nov 1999 10:50:43 -0500

Jonathan said:

I don't think Matt was proposing that MED apply across providers. Matt
said:

> I think all we need to do is to add wording to the effect that the
> MultiExitDisc parameter can be included by an LS when it inserts itself as
> the next hop, and that the MultiExitDisc parameter should be used by *any*
> receiver to discriminate between multiple routes to a particular
> destination thru the same first hop domain.  

>Note the last sentence "thru the same first hop domain". 

ok, I interpreted differently, exactly as Hussein (see below):

"Note also that in Section 6.8.5, the first paragraph needs to be
changed, since now the MED attribute will be propagated from one ITAD to
another without changes as long as the next hop signaling server
attribute does not change.

Hussein"

ie, the MED would reflect the "sum" of the cost of the signalling routes along the way.

>I think Matt's proposed wording is good. Note that given this wording, I
>think RoutedPath need not be mandatory, since you can always get the
>next hop ITAD from the next hop attribute, which is mandatory. As MED
>applies to the next signalling hop, this is sufficient.

Will I be able in this scheme to choose the signalling route based on the number of Hop (ITADs) counts? Maybe I'm wrong but I think I still don't have this information coming to me in the packet since the advertisement path does not reflect this.

Reinaldo

___________________________

NortelNetworks
Systems Engineer
___________________________

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 12 Nov 1999 11:19:08 -0500

> Reinaldo Penno Filho wrote:
> 

No, not the sum. According to the above, the MED represents the
preference for this signaling hop from this ITAD. Each ITAD would
*change* this value completely to whatever it likes, if it modifies the
next hop. I do not believe Hussein is proposing that MED have meaning
cross ITADs, or represent the sum of preferences along the whole path. 

> Will I be able in this scheme to choose the signalling route based on
> the number of Hop (ITADs) counts? Maybe I'm wrong but I think I still
> don't have this information coming to me in the packet since the
> advertisement path does not reflect this.

The number of ITADs is in the SignalingPath attribute. If you feel you
want this information always, we can still make the attribute mandatory.
My point above was only that to usefully used MED, you don't need the
SignalingPath.

-Jonathan R.
-- 
Jonathan D. Rosenberg                       200 Executive Drive
Chief Scientist                             Suite 120 
dynamicsoft                                 West Orange, NJ 07052
[email-masked]                     FAX:   (732) 741-4778
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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From: "Hussein F. Salama" <[email-masked]>
Date: Fri, 12 Nov 1999 11:42:43 -0800

> cross ITADs, or represent the sum of preferences along the whole path.

Correct. 

Hussein

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