Re: [CCAMP] draft-ietf-ccamp-te-metric-recording-02

Matt,

John's point is that the costs of a TE link in a client layer are not "something vague"  or something absolute as you imply, rather, something that can relate said TE link to other client layer TE links, and such costs have nothing to do with the costs of the server LSPs supporting them. Consider the following:
a) static client  layer TE link 0;
b) client layer TE link 1 supported by a server layer LSP1 in server domain 1;
c) client layer TE link  2 supported by a server layer LSP2 in server domain 2

The point is that the costs collected for, say,  LSP1 do not help in any way to define the costs of TE Link1 as compared to costs of TE link 0 or TE link2;

Cheers,
Igor

-----Original Message-----
From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On Behalf Of Matt Hartley (mhartley)
Sent: Friday, August 09, 2013 11:07 AM
To: John E Drake; CCAMP (ccamp@ietf.org)
Subject: Re: [CCAMP] draft-ietf-ccamp-te-metric-recording-02

John,

The point you raise is a good one, but I don't think it has much to do with this draft.

> I think there is a basic issue with this draft, which is that the 
> server network manages its own TE metrics and those metrics almost 
> certainly have nothing in common with the TE metrics used in a given client network.

So if I understand you correctly, you're just saying that "cost" is a somewhat vague thing that may mean different things to different network operators? This is true sometimes, but that doesn't mean it will always be the case. And I think concepts such as latency and latency variation are less prone to this problem; when we talk about "latency", I'm reasonably sure we all mean the same thing.

> Given this, would it not be better to have policy in the client nodes 
> that maps the characteristics of a given LSP established across the 
> server network into the TE metric to be advertised with that LSP in the client network?

Certainly that might be a good idea... but it's beyond the scope of this draft. If you want to map the characteristics of a given LSP established across the server network into the TE metric to be advertised with that LSP in the client network, you first have to know what the characteristics of the LSP across the server network are... and that's what this draft is for; it's simply about the discovery of the information, not what you choose to do with it afterwards.

Cheers

Matt

> 
> Yours Irrespectively,
> 
> John
> 
> 
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