Hi John, On Wed, Apr 7, 2021 at 10:02 PM John Scudder <[email protected]> wrote: > Hi Donald, > > Thanks for your reply. > > On Apr 7, 2021, at 9:22 PM, Donald Eastlake <[email protected]> wrote: > > ... > > 2. Section 2.3: > > EVPN Network OAM mechanisms MUST provide in-band monitoring > capabilities. As such, OAM messages MUST be encoded so that they > exhibit identical entropy characteristics to data traffic in order > that they share the same fate. > > It’s not obvious to me what you mean by “identical entropy characteristics to > data traffic”. Surely, different flows may have different entropy > characteristics, so, *which* data traffic? Similarly, with which data traffic > are you saying the OAM messages must share fate? > > ><de> Well, it depends on what is meant by "characteristics". I believe the ><de>intent is to say that with a sufficient quantity of OAM messages, all ><de>paths used by actual data will be exercised. > > > Your explanation (“all paths… will be exercised”) seems inconsistent with §3.1.1.1: > > - all paths. For MPLS/IP networks with ECMP, monitoring of all > unicast paths between MEPs (on non-adjacent nodes) may not be > possible, since the per-hop ECMP hashing behavior may yield > situations where it is impossible for a MEP to pick flow entropy > characteristics that result in exercising the exhaustive set of > ECMP paths. Monitoring of all ECMP paths between MEPs (on non- > adjacent nodes) is not a requirement for EVPN OAM. > > Even if the above somehow isn't the issue it appears to be, I think it’s evident that the §2.3 text in question isn’t unambiguous enough to have a MUST applied to it, I think this needs to be rectified in some way. I’m going to switch my ballot to a DISCUSS until we’ve resolved this. > > (Now that I’m looking at the §2.3 text again, “identical” bugs me too, since identity is a much stronger requirement than, say, similarity. But since I suspect the text will be rewritten anyway it’s not worth dwelling on.)
<de>Geez, here I put this text, which I inherited when I became pen holder after draft-salam-l2vpn-evpn-oam-req-frmwk, in the best possible light and you still object ! :-) <de> OK, how about something more like: EVPN Network OAM mechanisms MUST provide in-band monitoring capabilities. OAM messages SHOULD be encoded so that they exhibit similar entropy characteristics to data traffic in order maximize the fate sharing between OAM and data. <de> Thanks, Donald ============================= Donald E. Eastlake 3rd +1-508-333-2270 (cell) 2386 Panoramic Circle, Apopka, FL 32703 USA [email protected] > Thanks, > > —John
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