[CCAMP] R: Objective function draft

"BELOTTI, SERGIO (SERGIO)" <sergio.belotti@alcatel-lucent.com> Tue, 18 September 2012 13:23 UTC

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From: "BELOTTI, SERGIO (SERGIO)" <sergio.belotti@alcatel-lucent.com>
To: "Beller, Dieter (Dieter)" <dieter.beller@alcatel-lucent.com>, Daniele Ceccarelli <daniele.ceccarelli@ericsson.com>
Date: Tue, 18 Sep 2012 15:22:32 +0200
Thread-Topic: [CCAMP] Objective function draft
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Subject: [CCAMP] R: Objective function draft
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Fully agree with your comments too.



Belotti Sergio - System Architect
ALCATEL-LUCENT  Optics Division
Da: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] Per conto di Dieter Beller
Inviato: martedì 18 settembre 2012 11.53
A: Daniele Ceccarelli
Cc: ccamp@ietf.org
Oggetto: Re: [CCAMP] Objective function draft

Hi Daniele, all,


I fully agree with your comments/clarifications.

On 18.09.2012 09:19, Daniele Ceccarelli wrote:


Fully agree on the second part of your statement. At the time of RFC4208 the UNI allowed the exchange of signaling and routing messages. Now that we're defining also the E-NNI i would prefer to have:

- UNI: signaling only

- E-NNI: signaling AND routing (i would prefer to call it reachability rather than routing, because it is not a topology info)

That said, i think that objective function (despite the correct comments from Julien) is not routing but a constraint. The ingress node of the overlay network asks the ingress node of the core network for a path computation with given constraints.

Viceversa in the case of E-NNI if the objective function was exported to the overlay network as a "property" of a virtual link, then i agree it was routing (reachability) information.



-----Original Message-----

From: ccamp-bounces@ietf.org<mailto:ccamp-bounces@ietf.org> [mailto:ccamp-bounces@ietf.org]

On Behalf Of Gert Grammel

Sent: lunedì 17 settembre 2012 23.22

To: George Swallow (swallow); Julien Meuric

Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>

Subject: Re: [CCAMP] Objective function draft

Hi George,

The objective function is in the end a routing information.

Mixing routing and signaling in one protocol is something I

don't feel comfortable with.

In other words, if routing is needed between client and

server, UNI is the wrong choice. ENNI should be considered

instead and Draft-beeram-ccamp-gmpls-enni would be a good

starting point.



From: ccamp-bounces@ietf.org<mailto:ccamp-bounces@ietf.org> on behalf of George Swallow (swallow)

Sent: Monday, September 17, 2012 12:19:21 PM

To: Julien Meuric

Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>

Subject: Re: [CCAMP] Objective function draft

Hi Julien -

On 9/17/12 9:37 AM, "Julien Meuric" <julien.meuric@orange.com><mailto:julien.meuric@orange.com> wrote:

Hi George.

Sorry for the late response. You are right: the minutes are

not enough

to trace the full discussion (which we also resumed right after the

meeting). Let us start by thanking Adrian (as AD? former PCE co-chair?

author of... ;-) ) for bringing the PCE-associated vocabulary to a

common understanding.

Actually my concern is sustained by 2 points:

1- The scope of the draft is about giving control of the routing

objective function to the client node facing a transport layer. I see

already several existing solution to achieve it:

- a PCEP request from the signaling head node is an option (which is

associated to the advertisement of the supported objectives in PCEP);

- building IGP adjacencies between client and transport edge nodes

(a.k.a. "border model") is another one.

In this context, it do not think extending RSVP-TE for this kind of

application is worth the effort, since the requirement can already be


As I understand it, in the optical and OTN cases, the border

model would not be popular as in many organizations this

crosses political boundaries.

The point of the draft is to keep the UNI implementation

simple and not require a PCEP on the uni-c or necessarily on

the uni-n.  We will keep the format aligned so if the UNI-N

needs to make a request of a PCS, it can do so rather simply.

2- There are cases when previous options are ruled out of a given

deployment. I do believe that it is not simply due to protocol

exclusion, but rather to the fact that the SP wants transport routing

decisions to remain entirely within the transport network (in

order to

fully leave the routing policy in the hands of people doing the layer

dimensioning). Thus, I feel this trade-off in path selection

tuning is

rather unlikely to happen and I fear we may be talking about RSVP-TE

over-engineering here.

The idea is simply to allow the client to express its

needs/wishes.  The UNI-N remains in control.  By policy it can

use the objective function or not.  Further if it does use the

objective function and fails to find a path it can either say

that there was no path or it proceed to setup what it can.

(That is also why I preferred to consider your I-Ds separately during

the CCAMP meeting.)

Agreed.  I will ask for separate slots.  The discussion at the

end was rather disjointed.

However, my comments are mostly related to the client/transport

relationship. If the I-D is extended to cover more use cases

with wider

scopes (Adrian has made interesting suggestions), turning the overlay

interconnection into one among a longer list, then my

conclusion may be


I'm happy to widen the scope in this way.




Le 11/09/2012 21:28, George Swallow (swallow) a écrit :

Julien -

Reading the CCAMP notes (which capture little of the actual

discussion) I see that there may have been a perception in the room

that PCE functionality at the UNI-N was assumed (actual or proxy).

This is not the case. The reason for our draft is that with

the UNI,

much of the functionality that resides at the headend is

moved to the

UNI-N. So the UNI-C needs a way to express an objective

function even

if there is no PCE.

Operationally it seems burdensome to require a PCEP at the

UNI-C and

a PCEP at the UNI-N, when all that is being done is enabling the

UNI-N to perform what the client would do if it were

connected to the

network via a normal link.

Do you still object to the draft?




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