Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-pw-protection-01.txt
Huub van Helvoort <huubatwork@gmail.com> Mon, 29 September 2014 13:34 UTC
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Date: Mon, 29 Sep 2014 15:33:56 +0200
From: Huub van Helvoort <huubatwork@gmail.com>
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Subject: Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-pw-protection-01.txt
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Hello, I agree with the assessment from Andy. Use the mechanism in RFC6478 also for PW. A single approach is much less complex to provision. Suppose there is a second approach, do _we_ have to search for it? Then it has to determined which is preferred/better to use as default, Maybe there is even a third approach... Best regards, Huub. > The mechanism for static PW failure handling is in RFC 6478, which is > also referenced in the draft. > > The primary purpose for an RFC is interoperability. If the draft > contains more than one approach, then one of those approaches has to be > mandatory to implement and use, and the other optional, otherwise you > can't assure interoperability. In which case, does it make sense to > include more than one approach and make one optional to implement? And > of course, if you implement both, then the primary approach has to be > the default one used. Then you'll also require either consistent > provisioning to make sure that the two ends agree on the approach used, > or a negotiation mechanism. It seems like you're adding a lot of work to > document more than one approach. > > Cheers, > Andy > > > On Mon, Sep 29, 2014 at 8:03 AM, Alexander Vainshtein > <Alexander.Vainshtein@ecitele.com > <mailto:Alexander.Vainshtein@ecitele.com>> wrote: > > Andy,____ > > Lots of thanks for a prompt and detailed response. Please see more > */inline below/*.____ > > __ __ > > Regards,____ > > Sasha ____ > > Email: Alexander.Vainshtein@ecitele.com > <mailto:Alexander.Vainshtein@ecitele.com>____ > > Mobile: 054-9266302____ > > __ __ > > *From:*Andrew G. Malis [mailto:agmalis@gmail.com > <mailto:agmalis@gmail.com>] > *Sent:* Monday, September 29, 2014 2:46 PM > *To:* Alexander Vainshtein > *Cc:* pwe3@ietf.org <mailto:pwe3@ietf.org> > *Subject:* Re: [PWE3] Fwd: I-D Action: > draft-shawam-pwe3-ms-pw-protection-01.txt____ > > __ __ > > Sasha,____ > > __ __ > > Thanks for your comments. In order:____ > > __ __ > > 1. No, the intended scope of this draft is Section 3.2.3 of RFC 6718 > and Section A.5 of RFC 6870, which describe a single-homed CE. They > both use the same network model diagram. I hadn't thought it was > necessary to replicate that diagram a third time, but I certainly > can and will in the next revision.*/[[Sasha]] Great! /*____ > > __ __ > > 2. This is actually discussed in those two sections. Basically, the > entire primary PW is protected against failure by switching to the > secondary PW if the primary fails for any reason. In the case of a > MS-PW where the individual segments are each protected via tunnel > protection, the likely cause of primary PW failure would be S-PE > failure.*/[[Sasha]] I have looked up these sections again, and they > say “If active/primary PW fails…”. They also mention that typically > the reason for PW failure (end-to-end) is S-PE failure. But no > specific method for detecting the failure of the primary/active PW > is mentioned. Maybe this should be expanded a bit in the draft with > emphasis on methods that are specific to MPLS-TP and statically > configured MS-PWs? /*____ > > __ __ > > 3. You're actually thinking of the -00 revision of this draft. That > is the approach that was presented at the Toronto PWE3 meeting, and > the consensus of the discussion was that the approach in this > revision should be used instead.*/[[Sasha]] Could be my mistake. And > even if the approach has been changed from -00 to -01, I think that > mentioning an alternative approach would be nice IMO. /*____ > > __ __ > > Cheers,____ > > Andy____ > > __ __ > > On Sun, Sep 28, 2014 at 1:03 AM, Alexander Vainshtein > <Alexander.Vainshtein@ecitele.com > <mailto:Alexander.Vainshtein@ecitele.com>> wrote:____ > > Andy,____ > > I've read the draft and re-read RFC 6780, and I have a couple of > questions/comments that, from my point of view, should be clarified > in the next revision of the draft.____ > > 1. RFC 6780 and RFC 6718 describe multiple use cases for PW > redundancy, including use cases with dual-homed CEs, use cases > for VPLS etc. The draft refers to specific sections in these > RFCs that deal with the /use case of two single-homed CEs, so I > guess that this is the intended scope of the draft/. Is this > assumption correct? If yes, I would suggest stating this > explicitly and even including the corresponding reference > network model diagram in the draft. This would not unduly expand > the document while making it much more readable IMO. (And maybe > you should mention > draft-cheng-pwe3-mpls-tp-dual-homing-protection a dealing with > the dual-homing use cases?) ____ > 2. RFC 6870 does not explain how S-PE failure is detected. I assume > that one of the possible ways to do that could be by treating > failure of the targeted/indirect LDP session between this S-PE > and its adjacent PEs as S-PE failure. This is clearly not > relevant in the case of statically set up MS-PWs. I would > suggest adding a few words regarding possible methods for > detecting S-PE failure. (As an absolute minimum, you could state > that this is out of scope of the document...)____ > 3. To the best of my recollection somebody has once posted a > draft that suggested treating static MS-PWs as MPLS-TP co-routed > bi-directional LSPs (which is true)and applying LSP Linear > Protection for end-to-end protection of MS-PWs. This draft has > long expired, but maybe the idea should be mentioned as a > possible alternative approach?____ > > With these points in mind, I think that the draft is mature enough > to be adopted as a WG document (even if you did not ask for that:-). > ____ > > ____ > > Regards,____ > > Sasha____ > > ------------------------------------------------------------------------ > > *From:*pwe3 <pwe3-bounces@ietf.org <mailto:pwe3-bounces@ietf.org>> > on behalf of Andrew G. Malis <agmalis@gmail.com > <mailto:agmalis@gmail.com>> > *Sent:* Saturday, September 27, 2014 6:02 PM > *To:* pwe3@ietf.org <mailto:pwe3@ietf.org> > *Subject:* [PWE3] Fwd: I-D Action: > draft-shawam-pwe3-ms-pw-protection-01.txt____ > > ____ > > PWE3ers, ____ > > __ __ > > Revision -00 of this draft was presented at the Toronto IETF and we > received good feedback from the WG. We've updated the draft to > incorporate the received comments. The draft plugs an important hole > in resilience for static MS-PWs. Please review and comment to the > list, it's a very quick read.____ > > __ __ > > Thanks,____ > > Andy____ > > __ __ > > ---------- Forwarded message ---------- > From: <internet-drafts@ietf.org <mailto:internet-drafts@ietf.org>> > Date: Fri, Sep 26, 2014 at 6:05 PM > Subject: I-D Action: draft-shawam-pwe3-ms-pw-protection-01.txt > To: i-d-announce@ietf.org <mailto:i-d-announce@ietf.org> > > A New Internet-Draft is available from the on-line Internet-Drafts > directories. > > Title : S-PE Outage Protection for Static > Multi-Segment Pseudowires > Authors : Andrew G. Malis > Loa Andersson > Huub van Helvoort > Jongyoon Shin > Lei Wang > Alessandro D'Alessandro > Filename : draft-shawam-pwe3-ms-pw-protection-01.txt > Pages : 5 > Date : 2014-09-26 > > Abstract: > In MPLS and MPLS-TP environments, statically provisioned Single- > Segment Pseudowires (SS-PWs) are protected against tunnel > failure via > MPLS-level and MPLS-TP-level tunnel protection. With statically > provisioned Multi-Segment Pseudowires (MS-PWs), each segment of the > MS-PW is likewise protected from tunnel failures via MPLS-level and > MPLS-TP-level tunnel protection. However, static MS-PWs are not > protected end-to-end against failure of one of the switching PEs > (S-PEs) along the path of the MS-PW. This document describes how to > achieve this protection by updating the existing procedures in RFC > 6870. > > > The IETF datatracker status page for this draft is: > https://datatracker.ietf.org/doc/draft-shawam-pwe3-ms-pw-protection/ > > There's also a htmlized version available at: > http://tools.ietf.org/html/draft-shawam-pwe3-ms-pw-protection-01 > > A diff from the previous version is available at: > http://www.ietf.org/rfcdiff?url2=draft-shawam-pwe3-ms-pw-protection-01 > > > Please note that it may take a couple of minutes from the time of > submission > until the htmlized version and diff are available at tools.ietf.org > <http://tools.ietf.org>. > > Internet-Drafts are also available by anonymous FTP at: > ftp://ftp.ietf.org/internet-drafts/ -- ***************************************************************** 请记住,你是独一无二的,就像其他每一个人一样
- [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-pw-p… Andrew G. Malis
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Alexander Vainshtein
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Andrew G. Malis
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Alexander Vainshtein
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Andrew G. Malis
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Huub van Helvoort
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Alexander Vainshtein
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Andrew G. Malis
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Alexander Vainshtein
- Re: [PWE3] Fwd: I-D Action: draft-shawam-pwe3-ms-… Andrew G. Malis