Bruno, If you like we could say that the EC value field is an unsigned integer which by default represents the attachment circuit bandwidth in units of 1 GBPS. (As an aside, if six octet unsigned integer arithmetic is difficult, we could say that the value field is a four octet unsigned integer that is right hand justified within the six octet value field.)
If a value other than attachment circuit bandwidth is being represented, it must be configured consistently on all of the PEs attached to a given ES. Yours Irrespectively, John Juniper Business Use Only From: bruno.decra...@orange.com <bruno.decra...@orange.com> Sent: Thursday, May 6, 2021 10:06 AM To: John E Drake <jdr...@juniper.net> Cc: slitkows.i...@gmail.com; bess@ietf.org; Neeraj Malhotra <neeraj.i...@gmail.com> Subject: RE: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb [External Email. Be cautious of content] John, > It's *not* all egress PEs, it's only the multi-homed PEs attached to the same > ES that need to be configured consistently Agreed. But step by step consistency becomes nice to have on all PEs: on a given PE, you probably don't want to mix and match different units on a per ES basis. So consistency per PE. Since an ES may be attached to different PEs, it's easier to have consistency across PEs within a domain. Then you have multi domains scenarios, including a new domain been involved long after the original network design. In the absence of global consistency, at some point when you have to merge PE/domains/VPNs the inconsistency becomes problematic and requires some special cases/handling. Seems simpler to ensure consistency by default. At least to me. We are not even discussing reducing the number of options, not to mention to one. We are only discussing to pick one per default so that we get interop by default. This point may be moved to a deployment consideration section if you believe that this hurts the specification. But I feel that it may have impact on implementations e.g. one cli/yang model/documentation referring to bit/s while the other one referring to bytes/s... and voilà we are likely to have inconsistencies. Regards, --Bruno From: John E Drake [mailto:jdr...@juniper.net] Sent: Thursday, May 6, 2021 3:37 PM To: DECRAENE Bruno TGI/OLN <bruno.decra...@orange.com<mailto:bruno.decra...@orange.com>> Cc: slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>; bess@ietf.org<mailto:bess@ietf.org>; Neeraj Malhotra <neeraj.i...@gmail.com<mailto:neeraj.i...@gmail.com>> Subject: RE: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb Bruno, It's *not* all egress PEs, it's only the multi-homed PEs attached to the same ES that need to be configured consistently. This is exactly the same requirement that we have for Ethernet Tag in RFC 8484: https://datatracker.ietf.org/doc/html/rfc8584#section-1.1<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/rfc8584*section-1.1__;Iw!!NEt6yMaO-gk!QPl16s6_2hw-s8FGIDB05lj2KQi4jSOPQr2JwnEw8gjz_4E8O8fBA8RQcG2udw4$>. Yours Irrespectively, John Juniper Business Use Only From: bruno.decra...@orange.com<mailto:bruno.decra...@orange.com> <bruno.decra...@orange.com<mailto:bruno.decra...@orange.com>> Sent: Thursday, May 6, 2021 9:16 AM To: John E Drake <jdr...@juniper.net<mailto:jdr...@juniper.net>> Cc: slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>; bess@ietf.org<mailto:bess@ietf.org>; Neeraj Malhotra <neeraj.i...@gmail.com<mailto:neeraj.i...@gmail.com>> Subject: RE: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb [External Email. Be cautious of content] Hi John, Personally, I would prefer that the text indicates the default/standardized usage, such that by default, if all operators follow this, this just works. Proposing no default and that everyone be free to pick his own unit seem to me a path for domain1/AS1/VPN1 picks unit 1 and domain2/AS2/VPN2 picks unit 2. Then in case of merge, inter-domain/AS/VPN, we may ends up using inconsistent units. > This ensures that when an ingress PE is doing weighted load balancing, in all > cases it is doing simple integer arithmetic on values whose semantics are > unknown to it." I think that we all agree with this. But this assumes and hence requires that all egress PEs use the same unit. Having a single unit (e.g., bytes/s) is a simple way to ensure this. If one want to state multiple options, stating the easy default and providing a warning for variations seems to increase the probability of consistency in various cases (including the one above e.g. network merges). IOW, to me the unit/semantic is part of the interoperability and hence standard. It's only about encoding/syntax. e.g. my outdoor temperature is 30°. Does this sound hot or cold to you? Thanks, --Bruno From: John E Drake [mailto:jdr...@juniper.net] Sent: Thursday, May 6, 2021 2:54 PM To: DECRAENE Bruno TGI/OLN <bruno.decra...@orange.com<mailto:bruno.decra...@orange.com>>; Neeraj Malhotra <neeraj.i...@gmail.com<mailto:neeraj.i...@gmail.com>> Cc: slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>; bess@ietf.org<mailto:bess@ietf.org> Subject: RE: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb Bruno, I had suggested: "The value field in the link bandwidth EC is to be treated as a 6 octet unsigned integer and it is the provider's responsibility to encode it consistently across all of the PEs attached to a given ES. So, for example, if the provider wanted the EC to represent attachment circuit bandwidth, it should decide the units, e.g., 1 GBPS, and then encode the value field as a multiple of that unit. This ensures that when an ingress PE is doing weighted load balancing, in all cases it is doing simple integer arithmetic on values whose semantics are unknown to it." Yours Irrespectively, John Juniper Business Use Only From: BESS <bess-boun...@ietf.org<mailto:bess-boun...@ietf.org>> On Behalf Of bruno.decra...@orange.com<mailto:bruno.decra...@orange.com> Sent: Thursday, May 6, 2021 4:04 AM To: Neeraj Malhotra <neeraj.i...@gmail.com<mailto:neeraj.i...@gmail.com>> Cc: slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>; bess@ietf.org<mailto:bess@ietf.org> Subject: Re: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb [External Email. Be cautious of content] Hi Neeraj, Thanks for considering my comments. Much better from my perspective. Thank you. I have two comments on the changes: - Regarding deployments §4.1 allows two rather incompatible encodings/usages with no way to detect which one is used: some PE could advertise the bandwidth in bytes, while some other PE could advertise a general weight. I understand that both works, but to me there is a significant risk of issues over time or between domain/SP. I'd prefer that you only chose one in order to favour consistency in deployments and usage and I would prefer the real bandwidth (at least for consistency with the name of the community, but also because this is not subjective) (And if a SP really wants to put an arbitrary value, I think he will figure out by himself, that it can do so). If you disagree with the above, then I would have a comment on the two below sentences: An implementation may support one or more of the above ways of encoding the value. Operator MUST ensure consistent encoding of this value across all PEs in an ethernet segment. Logic dictates that the second sentence (MUST) can only be fulfilled if the first sentence mandates that all implementations MUST support both options, or one specifically defined. - Regarding existing implementations: previous version of the draft did not really specify the format of the EVPN EC. I had personally assumed that the format was similar to the draft-ietf-idr-link-bandwidth link bandwidth community hence encoded in IEEE floating point format. Latest version of the draft defines it in unsigned integer. Integer looks good to me, but for an existing implementation this may be seen as an incompatible change very late in the process. Obviously, if there are no implementation, there is no issue. In which case, you could also express the bandwidth in unit of bit/s _if you_ wish to. (I have no preference). However given that the draft had indicated a codepoint, there seem to be a risk of existing implementations hence incompatible change. BTW the codepoint is squatted even though the registry is FCFS hence easy to request. Thanks, --Bruno From: Neeraj Malhotra [mailto:neeraj.i...@gmail.com] Sent: Thursday, May 6, 2021 7:41 AM To: DECRAENE Bruno TGI/OLN <bruno.decra...@orange.com<mailto:bruno.decra...@orange.com>> Cc: slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>; bess@ietf.org<mailto:bess@ietf.org> Subject: Re: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb Hi Bruno, Many thanks for the review comments. We have revised the draft addressing your comments. More inline. Thanks, Neeraj On Mon, May 3, 2021 at 2:20 AM <bruno.decra...@orange.com<mailto:bruno.decra...@orange.com>> wrote: Hi Stéphane, authors, I have not followed the discussions on this document, but I'll nonetheless raise one point regarding the bandwidth community (better safe than sorry). - why has [BGP-LINK-BW] been moved to informational reference while its reading seem mandatory? [NM]: There was a leftover reference to this in one of the sections that has been fixed now to use new EVPN EC. With this, reference to [BGP-LINK-BW] is purely informational (as was intended). - A new EVPN Link Bandwidth extended community is defined, but I could not find its specification. I guess that this is the same format as [BGP-LINK-BW] but transitive. Could this be explicitly stated? [NM]: clarified in section 4. - [BGP-LINK-BW] advertises the bandwidth in unit of bytes (not bits!) per second. Could the unit of the new EVPN Link Bandwidth extended community be also clearly spelled out? Especially give the history on this (cf below). Also in order to avoid misleading the readers could the examples use the correct unit (vs bits per seconds as writen) [NM]: done. - 10 years ago or so, I had raised a similar point (distinction between bits and bytes) on [BGP-LINK-BW] in the IDR WG. And it turned out that 1 major implementation had implemented and deployed "bytes per second" as per the spec, while another implementation had implemented and deployed "bits per second" which is the typical unit of link bandwidth. Given the deployments, none was willing to change its implementation as it would be a non-backward compatible change with themselves. What's the status on this? Could we have an implementation status on this? [NM]: I don't have this information. Perhaps someone else could comment. Thanks Regards, --Bruno From: BESS [mailto:bess-boun...@ietf.org<mailto:bess-boun...@ietf.org>] On Behalf Of slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com> Sent: Monday, May 3, 2021 9:21 AM To: bess@ietf.org<mailto:bess@ietf.org> Subject: [bess] New short WGLC for draft-ietf-bess-evpn-unequal-lb Hi WG, We got final updates from authors on draft-ietf-bess-evpn-unequal-lb. I'm opening a new short Working Group Last Call (to be closed on 5/10) to get any last comments before moving to the next step. However, the document having normative references to EVPN PREF DF, and PER-MCAST-FLOW-DF, the draft will not be sent to IESG until these drafts are ready. Feel free to send comments to the list before next Monday. Thanks, Stephane https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-unequal-lb/<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-ietf-bess-evpn-unequal-lb/__;!!NEt6yMaO-gk!RXfyob-BQAdE2D2qzwgUOjGOeP3zn3ANqH6QLuU9WuDatlUvr_IFtXP90p4KAB8$> _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. 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