Hi Aijun, Please check inline below for responses.
On Tue, Apr 19, 2022 at 1:00 PM Aijun Wang <[email protected]> wrote: > Hi, All: > > I have the similar opinions as Les. > > Such mechanism is actually one maintenance tools and can’t be used to > accomplish the metric auto adjustment, as that described in section 2.1 > KT> Please check my response to Les and let us know if that is not addressing your concerns. > The scenario described in section 2.2 is somewhat problematic: AGGR1 > should calculate the adjusted metric value based on its POV, but the > adjustment will influence the traffic distribution within all the IGP > domain. Such automatic adjustment is dangerous, and is not one solution > that can be applied for the more general scenario. > KT> Any time the IGP metric is updated for a link, it does influence the traffic distribution in the IGP domain. This is a given and so I don't really understand your concern. This use case is very similar to the Spine Leaf one in RFC8500 - we can clarify that in the text. > > > Based on the above considerations, I think the authors should limit its > usage only for maintenance scenarios as described in RFC8500. > > For the encoding, I think the “offset” value and the “O” bit is not > necessary, because the meaningful “Reverse Metric” should be the maximum > value of the metric. > KT> The additive offset is there in RFC8500 as well and so I don't see why we would want to not have that in OSPF. Thanks, Ketan > > > Best Regards > > > > Aijun Wang > > China Telecom > > > > *From:* [email protected] <[email protected]> *On Behalf Of *Les > Ginsberg (ginsberg) > *Sent:* Tuesday, April 19, 2022 2:44 PM > *To:* Acee Lindem (acee) <[email protected]>; [email protected] > *Cc:* [email protected] > *Subject:* Re: [Lsr] Working Group Last Call for > draft-ietf-lsr-ospf-reverse-metric - "OSPF Reverse Metric" > > > > I support progressing this draft. > > However, I have some concerns about the current content – specifically the > use cases – which I would like to see addressed before going to Last Call. > > > > The equivalent functionality is defined in RFC 8500 for IS-IS and has > proven useful – make sense to also have it for OSPF. > > But the primary use case discussed in RFC 8500 is during maintenance – > which is discussed extensively and is mentioned as the first use case. > > In the case of draft-ietf-lsr-ospf-reverse-metric, the maintenance use > case is not even mentioned. > > > > Of the two use cases that are mentioned, the one in Section 2.1 has many > limitations and constraints. These include: > > > > · Only works when there is a switch in the middle – something which > the protocol is not able to detect > > · Only works in the presence of symmetrical metrics > > · If both neighbors have L2 bundles to the switch and are both > doing auto-cost adjustment based on the number of members currently up, the > mechanism doesn’t work > > · Detecting symmetrical metrics in the presence of reverse metric > is problematical. Is the neighbor cost including the reverse metric or does > it reflect something else (e.g., config change on the neighbor) > > > > I would prefer that this use case be removed. If not, a more complete > discussion of the limitations should be included. > > > > In summary, before progressing this draft I would like to see maintenance > included as the primary use case and the use case described in Section 2.1 > removed. > > > > Les > > > > > > *From:* Lsr <[email protected]> *On Behalf Of *Acee Lindem (acee) > *Sent:* Thursday, April 7, 2022 12:18 PM > *To:* [email protected] > *Cc:* [email protected] > *Subject:* [Lsr] Working Group Last Call for > draft-ietf-lsr-ospf-reverse-metric - "OSPF Reverse Metric" > > > > This begins a Working Group Last Call for > draft-ietf-lsr-ospf-reverse-metric. While there hasn’t been as much > discussion as I would like on the draft, it is filling a gap in OSPF > corresponding to IS-IS Reverse Metric (RFC 8500). Please review and send > your comments, support, or objection to this list before 12 AM UTC on April > 22nd, 2022. > > > > Thanks, > > Acee > > >
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