Re: [CCAMP] OVRLY - signaling extensions

Igor Bryskin <> Thu, 20 March 2014 14:37 UTC

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From: Igor Bryskin <>
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Thread-Topic: [CCAMP] OVRLY - signaling extensions
Date: Thu, 20 Mar 2014 14:36:36 +0000
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Subject: Re: [CCAMP] OVRLY - signaling extensions
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Hi Adrian,

I largely agree with what you said except for this:
" This is the thing I have been banging on about for a while. The UNI is not a service request interface it is an LSP signaling interface"

Using your own definition of service the client (albeit using RSVP-TE) actually requests a connectivity rather than LSP. For example, it is possible that that the network has nothing to do with GMPLS except for supporting UNI - the connectivity across the network domain is managed by an SDN controller and achieved in a form of an arbitrary mixture of individual cross-connects, stitched connection segments, etc.
Whether it is UNI, ENNI, Netconf, etc. the client actually requires a connectivity of some sort across the network with certain set of properties: resilience to network failures, optical signal quality, delay characteristics, etc.


-----Original Message-----
From: CCAMP [] On Behalf Of Adrian Farrel
Sent: Wednesday, March 19, 2014 6:34 PM
To: Paweł Brzozowski; 'Zhangxian (Xian)'; 'Gert Grammel'
Subject: Re: [CCAMP] OVRLY - signaling extensions

H Pawel,

> On the side note, I believe that e-mail exchange on the group does not 
> push us in any direction. It really does seem people are sending 
> e-mails just for the sake of conversation.

Please don't take that tone (unless, maybe, you were referring to yourself :-).

I have found the exchanges useful. They have caused me to go back and look at I-Ds that people have referenced (and to realise they said things I didn't recall that they said). 

More importantly, they caused me to understand better the line between fixing stuff to work with what we have, and dreaming up new extensions for a potential use in the future.

> If you are interested in discussing the points I’ve raised, I’ll be 
> happy to have a conference call with you. If not, no problem than, 
> let’s just forego this topic.

It's OK if you want to drop out of the discussion, and it's OK for you to talk to whoever you please, but please don't suggest that I should not talk about this topic on this list.

Anyway, your revised email says:

> I believe everybody agrees that there is a need in signaling for 
> indication that “this service should be diverse from services/ paths 
> A-Z”, since it is a generic extension.

But there we go, I have to dash your belief.
The problem is that you are talking about "services". 
A "service" is "connectivity" not "a connection".
You don't talk about a service having diversity, you talk about it having resilience. The resilience is achieved by mapping the service request to a number of underlying connections and to making those connections observe a number of diversity and protection group relationships.

I don't know whether your use of "service" was accidental and you meant "LSP" or whether it indicates a more fundamental issue.

I think that for a transport equipment provider (I was one) there is a tendency to think of addressing a request of an LSP as providing a service. But it isn't except in the most simple case of a service.

This is the thing I have been banging on about for a while. The UNI is not a service request interface it is an LSP signaling interface. 

> I agree with Adrian, from architectural perspective, there needs to be 
> a line beyond which putting steroids into a protocol becomes a mess. 
> E.g. I hope there will be no attempts to overcome multi-homed clients’ 
> deficiencies via extensions to signaling.

Nice to be agreed with once in a while.
But, of course, we have a number of I-Ds kicking about that are trying to do exactly this. It isn't clear to me that the line is being drawn and features are creeping.


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