[rsvp-dir] Fwd: RE: Redundant aggregate reservations: draft-ietf-tsvwg-rsvp-pcn-03
Bob Briscoe <bob.briscoe@bt.com> Tue, 20 November 2012 21:40 UTC
Return-Path: <bob.briscoe@bt.com>
X-Original-To: rsvp-dir@ietfa.amsl.com
Delivered-To: rsvp-dir@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D447921F866C for <rsvp-dir@ietfa.amsl.com>; Tue, 20 Nov 2012 13:40:02 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.155
X-Spam-Level:
X-Spam-Status: No, score=-3.155 tagged_above=-999 required=5 tests=[AWL=-0.157, BAYES_00=-2.599, HTML_MESSAGE=0.001, J_CHICKENPOX_44=0.6, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id WeLM9r+Ftvt5 for <rsvp-dir@ietfa.amsl.com>; Tue, 20 Nov 2012 13:40:00 -0800 (PST)
Received: from hubrelay-rd.bt.com (hubrelay-rd.bt.com [62.239.224.99]) by ietfa.amsl.com (Postfix) with ESMTP id 4FD5421F86BA for <rsvp-dir@ietfa.amsl.com>; Tue, 20 Nov 2012 13:39:58 -0800 (PST)
Received: from EVMHR71-UKRD.domain1.systemhost.net (10.36.3.109) by EVMHR68-UKRD.bt.com (10.187.101.23) with Microsoft SMTP Server (TLS) id 8.3.279.1; Tue, 20 Nov 2012 21:39:56 +0000
Received: from dyw02134app01.domain1.systemhost.net (193.113.249.13) by EVMHR71-UKRD.domain1.systemhost.net (10.36.3.109) with Microsoft SMTP Server (TLS) id 8.3.279.1; Tue, 20 Nov 2012 21:39:55 +0000
Received: from cbibipnt05.iuser.iroot.adidom.com (147.149.196.177) by dyw02134app01.domain1.systemhost.net (10.35.25.214) with Microsoft SMTP Server id 14.2.309.2; Tue, 20 Nov 2012 21:39:48 +0000
Received: From bagheera.jungle.bt.co.uk ([132.146.168.158]) by cbibipnt05.iuser.iroot.adidom.com (WebShield SMTP v4.5 MR1a P0803.399); id 1353447588498; Tue, 20 Nov 2012 21:39:48 +0000
Received: from MUT.jungle.bt.co.uk ([10.215.130.204]) by bagheera.jungle.bt.co.uk (8.13.5/8.12.8) with ESMTP id qAKLdkdb002838 for <rsvp-dir@ietfa.amsl.com>; Tue, 20 Nov 2012 21:39:46 GMT
Message-ID: <201211202139.qAKLdkdb002838@bagheera.jungle.bt.co.uk>
X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9
Date: Tue, 20 Nov 2012 21:39:47 +0000
To: rsvp-dir@ietfa.amsl.com
From: Bob Briscoe <bob.briscoe@bt.com>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="=====================_288126433==.ALT"
X-Scanned-By: MIMEDefang 2.56 on 132.146.168.158
Subject: [rsvp-dir] Fwd: RE: Redundant aggregate reservations: draft-ietf-tsvwg-rsvp-pcn-03
X-BeenThere: rsvp-dir@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: RSVP directorate <rsvp-dir.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rsvp-dir>, <mailto:rsvp-dir-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rsvp-dir>
List-Post: <mailto:rsvp-dir@ietf.org>
List-Help: <mailto:rsvp-dir-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rsvp-dir>, <mailto:rsvp-dir-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 20 Nov 2012 21:40:03 -0000
For the record, the posting below was blocked awaiting moderator approval due to too many recipients. I am re-sending just to the RSVP-DIR list that raised the objection. Bob >Date: Fri, 16 Nov 2012 20:14:33 +0000 >To: <karagian@cs.utwente.nl> >From: Bob Briscoe <bob.briscoe@bt.com> >Subject: RE: Redundant aggregate reservations: draft-ietf-tsvwg-rsvp-pcn-03 >Cc: <carlberg@g11.org.uk>, <tsvwg@ietf.org>, ><philip.eardley@bt.com>, <pcn@ietf.org>, <rsvp-dir@ietfa.amsl.com>, ><sob@harvard.edu>, <slblake@petri-meat.com>, <gorry@erg.abdn.ac.uk>, ><jmpolk@cisco.com>, <anuragb@cisco.com> > >Georgios, > >Yes, I apologise for not reviewing earlier. I appreciate you >followed the procedure. > >My problem was that a quick read of tsvwg-rsvp-pcn wasn't enough to >understand it. So I stayed quiet even though I wasn't so happy about >the direction, because I didn't have enough understanding to feel I >could argue. > >Only in the last week or so, I collected together all the references >and re-read them and their references, and made a concerted effort >to understand what your draft was proposing. I have to say, it was >quite a struggle (over a few days and the write-up took 2 days). > >However, I admit that it would have been preferable for everyone if >I had made this effort earlier. > > >Bob > >At 13:02 16/11/2012, karagian@cs.utwente.nl wrote: > >>Hi Bob, >> >>$B!!(B >> >>Thanks for your comments! >> >>Regarding your statement: What I meant in my previous email is that >>our individual draft that was used as a working basis for this WG >>draft was already using the generic aggregation RSVP (RFC 4860) as >>the existing signaling protocol, see: >> >> >> >><http://tools.ietf.org/id/draft-karagiannis-pcn-tsvwg-rsvp-pcn-01.txt>http://tools.ietf.org/id/draft-karagiannis-pcn-tsvwg-rsvp-pcn-01.txt >> >> >> >>Moreover, during IETF 81, this individual draft has been presneted, >>where also the rationale of using (RFC 4860) was also the following >>slides see presentation slides (slide 5): >> >> >> >>http://www.ietf.org/proceedings/81/slides/tsvwg-0.pdf >> >>$B!!(B >> >>In particular in slide 4 mentions: >> >>"All PCN charter items are fulfilled, except: >> >>Submit Encoding and Transport of PCN from Domain Egress to Ingress >>to the IESG for consideration as a Proposed Standard RFC >> >>Pairs of PCN edge nodes use ingress-egress-aggregates (IEA): >> >>Need a signaling protocol to transport PCN information from >>PCN-egress-node to PCN-ingress-node and to maintain >>ingress-egress-aggregate between each pair of PCN edge nodes" >> >>Furthermore Slide 5 mentions: >> >>$B!!(B >> >>"IETF QoS signaling protocols to solve problem: >> >>Next Steps in Signaling Protocol (NSIS) subset (RFC 5971, RFC 5974, RFC 5979) >> >>Aggregation of RSVP for IPv4 and IPv6 Reservations (RFC3175) >> >>Generic Aggregate Resource ReSerVation Protocol (RSVP) Reservations (RFC4860) >> >>All can be used, but for time being selected RFC 4860 due: >> >>possible deployment interest >> >>supports RFC 3175 and additional features such as: >> >>support of multiple IEAs from same pair of PCN edge nodes >> >>support of bandwidth reduction for individual flows (RFC 4495)" >> >>$B!!(B >> >>Before IETF 81 and during IETF 81 this point has been discussed. >> >>The outcome of these discussions is that short after IETF 81, the >>individual draft (draft-karagiannis-pcn-tsvwg-rsvp-pcn-01) >> >>become (after small modifications) the >>draft-ietf-tsvwg-rsvp-pcn-00, which also was using RFC 4860 as the >>base signaling protocol. >> >>$B!!(B >> >>It will be very helpful if the PCN WG chairs (Scott and/or Steve) >>and the tsvwg WG chairs (Gorry and/or James) could confirm the above statement! >> >>$B!!(B >> >>So both the PCN WG and tsvwg WG agreed that this specifictaion >>should use as basis the generic RSVP aggregation protocol! >> >>$B!!(B >> >>$B!!(B >> >>$B!!(B >> >>In a subsequent email and on a later moment I will also answer to >>your further remarks! >> >>$B!!(B >> >>Best regards, >> >>Georgios >> >>---------- >>Van: Bob Briscoe [bob.briscoe@bt.com] >>Verzonden: donderdag 15 november 2012 14:07 >>To: Karagiannis, G. (EWI); anuragb@cisco.com >>Cc: carlberg@g11.org.uk; anuragb@cisco.com; tsvwg@ietf.org; >>philip.eardley@bt.com; PCN IETF list; rsvp-dir@ietfa.amsl.com >>Onderwerp: Redundant aggregate reservations: draft-ietf-tsvwg-rsvp-pcn-03 >> >>Georgios, Anurag, >> >>Below is the main point of my review, arguing that aggregate >>reservations are redundant. I'm reviewing as: >>- a member of the RSVP directorate >>- one of the early PCN design team >>- a co-author of draft-lefaucheur-rsvp-ecn-01, on which this draft is based. >> >>I would have missed any decision to use aggregate reservations. Pls >>point me to the relevant discussion (e.g. Subject line / date). >> >>I admit I tuned out of much of the later PCN signalling discussion. >>I found the whole exercise of abstracting PCN away from specific >>signalling protocols highly tedious; it meant we couldn't sensibly >>address important issues like message reliability, timeliness etc. >> >>Nonetheless, here's why I believe RSVP aggregation is redundant: >> >>PCN edge-nodes support the concept of an ingress-egress aggregate >>in their own internal tables, but they don't need to refer to an >>aggregate on the wire{Note 1}. PCN-ingress and PCN-egress nodes >>intrinscially know which e2e reservations belong to which aggregate >>by grouping together those e2e reservations with the same next hop >>or previous hop respectively. >> >>{Note 1: except in one case described later - but it doesn't >>require all the other baggage of aggregate reservations} >> >>==Background== >>Aggregate reservations [RFC3175, RFC4860] are designed to reduce >>the state required on interior nodes. Interior nodes still require >>state per aggregate reservation, but only reservation state, not >>classification and scheduling state [RFC3175, Section 1.4.1 last para]. >> >>In contrast, as you correctly point out (in Section 2.1.7), PCN >>requires absolutely no reservation-related state on interior nodes. >> >>==Disadvantages== >>Requiring PCN to use aggregate reservations has the following three >>disadvantages and no advantages: >> >>1) Redundant Processing >>The PATH message between aggregator and deaggregator in rsvp-pcn-03 >>(triggered by an E2E PathErr message from deaggregator to >>aggregator) is redundant, and just doubles the processing required >>at the PCN-edge-nodes (if this isn't obvious, I spell it out >>separately for PATH & RESV messages below). >> >>2) Reduced Resilience >>Not only is an aggregate PATH redundant, it actually reduces >>resilience. Because an aggregate PATH is pinned to interior >>routers. Therefore, when routing changes, it is more complex and >>slower to move to the new route. By not pinning to interior >>routers, PCN was designed to 'just work' over interior routing >>changes - with no need for any changes to the RSVP PATHs. (But it >>would still detect overload after a re-route and terminate or >>rate-reduce flows if necessary.) >> >>3) Extra Latency >>A further disadvantage is the extra latency required for the first >>reservation that sets up an aggregate. This is two ingress-egress >>round trips minus the round trip time from egress to destination >>(or one ingress-egress round trip if it is greater). This will >>rarely add to latency on heavily used ingress-egress aggregates, >>but it will occur frequently on all the 'long-tail' (lightly used) >>ingress-egress aggregates. >> >>==PATH== >> >>With RFC 3175 or 4860 aggregate paths, the aggregator forwards the >>e2e PATH messages with IP protocol number RSVP-E2E-IGNORE and the >>deaggregator changes them back to RSVP before forwarding onward. >>Also the aggregator sends an aggregate PATH message, which is >>processed by each interior node and by the deaggregator. >> >>On a path across a PCN region, given interior nodes ignore >>aggregate PATH messages as well, the only PCN nodes that handle >>aggregate messages are the aggregator and the deaggregator. The >>aggregator and deaggregator process all the e2e PATH messages >>anyway, so if we require the aggregator to add up all the e2e PATH >>messages and form them into an aggregate PATH message, this is just >>extra redundant work for both PCN-edge-nodes. >> >>==RESV== >> >>The deaggregator unicasts e2e RESV messages to the previous RSVP >>hop, which is the aggregator. Therefore, if we require the >>deaggregator to add up all the RESV messages and form them into an >>aggregate RESV message, this is just redundant work for both >>PCN-edge-nodes, because they both already process all the e2e RESV >>messages anyway, and no other node uses the aggregate RESV messages. >> >>==PCN object== >> >>This raises the question of how the PCN-egress communicates the >>various marking rates (the PCN object) to the PCN-ingress. There >>are two possibilities: >>i) the PCN-egress includes a current PCN object in each e2e RESV >>that it returns to the PCN-ingress. The PCN-ingress strips the PCN >>object out before forwarding the RESV back to the previous RSVP hop. >>ii) the PCN-egress attaches a PCN object to an aggregate >>reservation, as in pcn-rsvp-03. >> >>Either are possible, because a PCN object carries information about >>marking probabilities, and PCN works on the assumption that the >>marking probability of an ingress-egress aggregate is the same as >>the marking probability of the flows within the aggregate. A PCN >>object can be contained either in an e2e RESV or an aggregate RESV >>as long as the PCN-ingress can associate an e2e RESV with the >>correct aggregate (which it can, because it maintains an internal >>table of mappings between e2e reservations and their aggregates). >> >>Which of the two is best is a question of message timing... >> >>* For e2e admission decisions, the PCN object is only needed at the >>time each e2e RESV is sent, so option i) makes sense. >> >>* For flow rate reduction or flow termination decisions, the >>deaggregator needs to regularly send PCN objects to the ingress. >> >>The PCN-egress is sending regular e2e RESV refresh messages to the >>PCN-ingress, so a PCN object can be included in each of these. To >>ensure that PCN objects are sent often enough, I suggest the >>PCN-egress also maintains a timer per ingress-egress aggregate >>which it resets every time it sends a PCN object for that IEA. If >>the timer expires, the PCN-egress sends a PCN object to the >>PCN-egress even thought it was not triggered by an e2e RESV >>refresh. We could require the SESSION object in this message to >>refer to either of: >>a) any one of the e2e SESSIONs in the aggregate, >>b) the aggregate. >> >>In case (a), the message would need to somehow tell the ingress not >>to forward this RESV refresh to the RSVP previous hop. >> >>In case (b) in the PCN-ingress table of mappings between e2e >>SESSIONs and aggregate SESSIONs, it would include an entry for the >>aggregate that maps to itself. If the result of the look-up is the >>same as the input, it knows not to forward the RESV refresh further. >> >>The wire protocol doesn't need to identify whether the SESSION is >>an aggregate or not. This is the one case I mentioned at the start >>{Note 1} where an aggregate is referred to on the wire. >> >> >> >>In summary, PCN already reduces reservation state and processing to >>nothing on interior nodes. Adding aggregate reservations to PCN >>requires more processing and state, it unnecessarily pins routes to >>interior nodes and adds unnecessary latency. >> >> >>Bob >> >>At 18:23 14/11/2012, karagian@cs.utwente.nl wrote: >>>Hi Bob, >>> >>>Regarding the generic aggregated RSVP selection, actually the PCN >>>WG agreed with this selection! >>>This was actually the first step that was needed for this work, >>>and the PCN WG had no main objections on this selection! >>> >>>So I do not understand your remark that your comment will have >>>major implications! >>> >>>Please note that the generic aggregated RSVP is selected since the >>>PCN IEA are associated with flows that are aggregated at the >>>edges. So a signalling protocol that supports aggregation of flows >>>at the edges is very suitable for this purpose! The generic >>>aggregated RSVP is such a signalling protocol! >>> >>> >>>Best regards, >>>Georgios >>> >>> >>> >>> >>>From: Bob Briscoe [<mailto:bob.briscoe@bt.com>mailto:bob.briscoe@bt.com] >>>Sent: woensdag 14 november 2012 12:57 >>>To: Anurag Bhargava (anuragb) >>>Cc: Karagiannis, G. (EWI) >>>Subject: Re: [tsvwg] draft-ietf-tsvwg-rsvp-pcn-03 >>> >>>Anurag, >>> >>>I have my comments half-written up. I will try to finish them by >>>the end of today. >>> >>>They should be orthogonal to the PBAC comment below, so if you >>>wanted to start altering that area, I don't think it would waste >>>too much time. >>> >>>However, my main comments will concern the use of aggregated >>>reservations (as I said at the mic), so that could have major implications. >>> >>> >>>Bob >>> >>>At 20:14 13/11/2012, Anurag Bhargava (anuragb) wrote: >>> >>>Hi Bob, >>> Thanks for the comments. If U have some text that will be great >>> els I have also started putting some text on the topic U brought up. >>> May be we can conference after US thanksgiving week and >>> collaborate the text and try to move forward. >>> >>> Please let us know what might be a good time and I can schedule >>> a Webex conf. >>> >>>Thx >>>-Anurag >>> >>>From: "<mailto:karagian@cs.utwente.nl>karagian@cs.utwente.nl " >>><<mailto:karagian@cs.utwente.nl>karagian@cs.utwente.nl > >>>Date: Saturday, November 10, 2012 8:10 AM >>>To: "<mailto:bob.briscoe@bt.com>bob.briscoe@bt.com" >>><<mailto:bob.briscoe@bt.com>bob.briscoe@bt.com> >>>Cc: "<mailto:carlberg@g11.org.uk>carlberg@g11.org.uk" >>><<mailto:carlberg@g11.org.uk>carlberg@g11.org.uk>, Anurag Bhargava >>><<mailto:anuragb@cisco.com>anuragb@cisco.com>, >>>"<mailto:tsvwg@ietf.org>tsvwg@ietf.org" >>><<mailto:tsvwg@ietf.org>tsvwg@ietf.org>, >>>"<mailto:philip.eardley@bt.com>philip.eardley@bt.com " >>><<mailto:philip.eardley@bt.com>philip.eardley@bt.com > >>>Subject: RE: [tsvwg] draft-ietf-tsvwg-rsvp-pcn-03 >>> >>>Hi Bob, >>> >>> >>> >>>Thanks very much for the comments! I think that they are very useful! >>> >>> >>> >>>It will be very beneficiary for the fast progress of this draft if >>>you would like to contribute as a co-author to this draft and >>>write this additional section that describes "that the PCN-ingress >>>can refer flow admission and >>>termination decisions to a central decision point (using e.g. >>>COPS), which will respond to the PCN-ingress as per RFC2753. >>>(Alternatively the PCN-ingress could itself be the policy decision point.)" >>> >>> >>> >>>Best regards, >>> >>>Georgios >>> >>> >>> >>>---------- >>>Van: Bob Briscoe [<mailto:bob.briscoe@bt.com>bob.briscoe@bt.com] >>>Verzonden: vrijdag 9 november 2012 16:33 >>>To: Karagiannis, G. (EWI) >>>Cc: <mailto:carlberg@g11.org.uk>carlberg@g11.org.uk; >>><mailto:anuragb@cisco.com>anuragb@cisco.com; >>><mailto:tsvwg@ietf.org>tsvwg@ietf.org; EARDLEY, Phil >>>Onderwerp: Re: [tsvwg] draft-ietf-tsvwg-rsvp-pcn-03 >>> >>>Georgios, >>> >>>I shall post my full review of this draft in the next few days (needs >>>typing up - currently scribbled on a paper copy). This email is >>>solely in response to your answer about on-path vs off-path policy. >>> >>>At 18:55 04/11/2012, >>><mailto:karagian@cs.utwente.nl>karagian@cs.utwente.nl wrote: >>> >So in this case an additional signaling protocol will be >>> >needed to be specified that covers the signaling between the >>> >PCN-egress-node and the centralized node >>> >and between PCN-ingress-node and the centralized node. >>> >In PCN we decdided to only focus on the specification of the >>> >signaling protocol that completes the >>> >feedback loop from PCN-egress-node to PCN-ingress-node and to focus >>> >on the signaling protocol >>> >used between the edge nodes and the centralized node. >>> >>>When I/we originally designed CL-PCN over RSVP (2005), the idea was >>>that it would fit with the policy-based admission control (PBAC) >>>architecture of RFC2753. In this architecture, an Intserv node at the >>>ingress to a domain is the policy enforcement point (PEP), and it >>>refers to a logically centralised 'policy decision point' (PDP) for >>>decisions on which flows to block/terminate, typically using COPS. >>> >>>To make this doc fit the PBAC framework, all we have to do is: >>>* Describe the PCN-ingress only as the PCN-ingress and not as the >>>decision point (find 'decision' throughout doc and fix). >>>* Add a section saying the PCN-ingress can refer flow admission and >>>termination decisions to a central decision point (using e.g. COPS), >>>which will respond to the PCN-ingress as per RFC2753. (Alternatively >>>the PCN-ingress could itself be the policy decision point.) >>>* Refer to this new PBAC section from Section 3.11 giving the >>>admission decision procedure. >>> >>>* Some people might think this means COPS will need new protocol >>>elements to carry PCN marking rates to the policy decision point. But >>>PCN marking rates are irrelevant to the policy decision: the >>>PCN-ingress just uses PCN to determine whether it needs to block or >>>terminate, and it refers to the policy decision point for which flows >>>to block/terminate. >>> >>>* Unfortunately, neither of the two PCN system descriptions [RFC6661, >>>RFC6662] describe a PBAC-based case. The architecture [RFC5559] >>>refers to the PBAC framework [RFC2753] but unfortunately doesn't >>>spell out how it fits. Originally, I referenced PBAC from RFC5559, >>>but just as the PCN w-g was closing I realised that (some?) others in >>>the PCN w-g were working under the assumption that the only way to >>>talk to a centralised policy node was from the egress, possibly >>>without being aware of the contents of RFC2753. >>> >>>I think it's OK to introduce a new architectural arrangement in this >>>RSVP doc, given RFC2753 is specific to the way RSVP works. >>> >>> >>>Bob >>> >>> >>> >>>At 12:28 05/11/2012, >>><mailto:karagian@cs.utwente.nl>karagian@cs.utwente.nl wrote: >>> >Hi Ken, >>> > >>> >Thank you very much! >>> >We will try to catch Francois and discuss the last (in line) >>> issue with him! >>> > >>> >Best regards, >>> >Georgios >>> > >>> >________________________________________ >>> >Van: ken carlberg [<mailto:carlberg@g11.org.uk>carlberg@g11.org.uk] >>> >Verzonden: maandag 5 november 2012 13:23 >>> >To: Karagiannis, G. (EWI) >>> >Cc: <mailto:tsvwg@ietf.org>tsvwg@ietf.org; >>> <mailto:anuragb@cisco.com>anuragb@cisco.com >>> >Onderwerp: Re: draft-ietf-tsvwg-rsvp-pcn-03 >>> > >>> >Georgios, >>> > >>> > > Georgios: We will try to explain the rationale of why we consider >>> > that RSVP can only be used for the situation that the >>> > > decision point is collocated with the PCN-ingress-node. The main >>> > reason of this is that in the case that the >>> > > decision point is collocated with the PCN-ingress-node,the >>> > required signaling protocol used to complete a >>> > > feedback loop from egress to ingress can be an entirely on-path >>> > protocol, like what RSVP is. >>> > > In the situation that the the decision point is a centralized >>> > node, then the required signaling protocol >>> > > can be a combination of an on-path and off-path protocol. This is >>> > because the >>> > > decision point might not be located on the data path! So in this >>> > case an additional signaling protocol will be >>> > > needed to be specified that covers the signaling between the >>> > PCN-egress-node and the centralized node >>> > > and between PCN-ingress-node and the centralized node. >>> > > In PCN we decdided to only focus on the specification of the >>> > signaling protocol that completes the >>> > > feedback loop from PCN-egress-node to PCN-ingress-node and to >>> > focus on the signaling protocol >>> > > used between the edge nodes and the centralized node. >>> > > This is also the reason of why PCN WG decided to only focus on >>> > the situation that the decision point is >>> > > collocated with the PCN-ingress-node. >>> > >>> >Great, this is helpful, and this is the information that needs to be >>> >in the draft. >>> > >>> > >> 6) This comment is just for you to contemplate -- I'm not >>> > expecting any changes. >>> > >> I noticed that you have a fair number of SHOULD, and some SHOULD NOTs. >>> > >> And it seems a lot of this is a carry over from rfc-4860, so in >>> > a sense you are inheriting an approach that >>> > >> was agreed to from an earlier effort. But I wonder in the back >>> > of my mind, what impact occurs if >>> > >> an implementor doesn't follow the SHOULD? Does the design break >>> > in supporting PCN? >>> > >> Again, I want to stress that this isnt a show stopper, but I >>> > would appreciate it if you gave it some thought. >>> > > >>> > > Georgios: Yes, in several cases the design might break in >>> supporting PCN. >>> > > This is also the reason of using SHOULD instead of MAY. Do you >>> > want us to explain this in more detail in the draft? >>> > >>> >well, actually, I was more curious as to why a number of these cases >>> >are SHOULD instead of MUST. Again, the SHOULD's in your document >>> >seem to be a carry-over from rfc-4860 (which set the precedent), so >>> >its a bit unfair for you to explain what was done in an earlier >>> >effort. I just wanted to make sure you gave some thought to the >>> >subject. And if things will break if SHOULD is not followed by an >>> >implementer/configuration, then maybe you should be more stringent >>> >and change things to MUST. Perhaps a brief private conversation >>> >with Francois Le Faucheur will be helpful. >>> > >>> >cheers, >>> > >>> >-ken >>> >>>________________________________________________________________ >>>Bob Briscoe, BT Innovate & Design >>> >>>________________________________________________________________ >>>Bob Briscoe, BT Innovate & Design >> >>________________________________________________________________ >>Bob Briscoe, BT Innovate & Design > >________________________________________________________________ >Bob Briscoe, BT Innovate & Design ________________________________________________________________ Bob Briscoe, BT Innovate & Design
- [rsvp-dir] Redundant aggregate reservations: draf… Bob Briscoe
- Re: [rsvp-dir] [PCN] Redundant aggregate reservat… Bob Briscoe
- Re: [rsvp-dir] [PCN] Redundant aggregate reservat… Bob Briscoe
- Re: [rsvp-dir] [PCN] Redundant aggregate reservat… Bob Briscoe
- Re: [rsvp-dir] [PCN] Redundant aggregate reservat… Bob Briscoe
- [rsvp-dir] Fwd: RE: Redundant aggregate reservati… Bob Briscoe
- [rsvp-dir] Fwd: RE: Redundant aggregate reservati… Bob Briscoe