Re: [Last-Call] Opsdir last call review of draft-ietf-ospf-ospfv2-hbit-10
Padma Pillay-Esnault <padma.ietf@gmail.com> Fri, 08 November 2019 01:08 UTC
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From: Padma Pillay-Esnault <padma.ietf@gmail.com>
Date: Thu, 07 Nov 2019 17:07:54 -0800
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To: Tim Chown <tim.chown@jisc.ac.uk>
Cc: ops-dir@ietf.org, last-call@ietf.org, draft-ietf-ospf-ospfv2-hbit.all@ietf.org, lsr@ietf.org, Padma Pillay-Esnault <padma.ietf@gmail.com>
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Subject: Re: [Last-Call] Opsdir last call review of draft-ietf-ospf-ospfv2-hbit-10
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Hi Tim Thank you for your review and comments. See below PPE. On Thu, Nov 7, 2019 at 2:22 PM Tim Chown via Datatracker <noreply@ietf.org> wrote: > Reviewer: Tim Chown > Review result: Has Nits > > I have reviewed this document as part of the Operational directorate's > ongoing > effort to review all IETF documents being processed by the IESG. These > comments were written with the intent of improving the operational aspects > of > the IETF drafts. Comments that are not addressed in last call may be > included > in AD reviews during the IESG review. Document editors and WG chairs > should > treat these comments just like any other last call comments. > > The document describes a mechanism by which a node running OSPFv2 can repel > transit traffic if it is on the shortest path (and an alternative path > exists - > though this is not wholly clear in the document). It defines a Host-bit > (H-bit) > that allows the router to advertise that it is not a transit router, and it > describes the changes needed to support the H-bit within a domain, and > mitigations against potential routing loops. > > General comments: > > Should the document also state that it updates RFC 2328? > > PPE> No. This has been discussed previously during the AD review. This feature is an optional feature and RFC2328 does not require it for normal operations. > I think the document could be clearer on the behaviour when the H-bit and > MaxLinkMetric are used when there is only one path available, i.e. there > is no > redundant / alternative path. Section 4 of RFC 6987 implies that if there > is > only one path the router can still be used as a transit router, by the > nature > of the definition of MaxLinkMetric. The document has 3 or 4 places where > it > hints at behaviour, but I think it could be more explicit. > > PPE> This feature goes one step further than RFC 6987 which is a best effort at stopping transit traffic. We believe that the behavior is clear that a "host router" is NOT used for transit traffic regardless whether it is the last resort path or not. Please note the CURRENT version does not restrict the feature on a specific number of paths (last resort or not) or metric value (MaxlinkMetric or not) or make any assumption in that way. However, I proposed to add this text in an earlier thread to make it even more explicit. CURRENT: This document describes the Host-bit (H-bit) functionality that prevents other OSPFv2 routers from using the host router for transit traffic in OSPFv2 routing domains. SUGGESTED NEW: This document describes the Host-bit (H-bit) functionality that prevents other OSPFv2 routers from using the host router by excluding it in path calculations for transit traffic in OSPFv2 routing domains. > It may be worth explicitly stating that OSPFv3 is not mentioned due to it > having an R-bit defined for indicating whether a node/router can be used > for > transit traffic (see Sections 2.7 and A.2 of RFC 5340). > > PPE> There was an earlier discussions regarding mentioning the OSPFv3 functionality and eventually these references were removed in subsequent versions of the H-bit draft. The R-bit is not exactly the same as H-bit, even though both are used for the similar functionality, they rely on different mechanisms in the protocol. > The reasons given in Section 1 for the need for the H-bit are different to > those given in Section 1 of RFC 6987 for the capability. Should these be > more > consistent? Also, the document later mentions “a router being gracefully > isolated” as a reason, but this is not mentioned in Section 1. > > PPE> We believe that this the document covers this case in bullet 1 and bullet 3 in section1. CURRENT 1. To isolate a router to avoid blackhole scenarios when there is a reload and possible long reconvergence times. <...> 3. Overloaded routers could use such a capability to temporarily repel traffic until they stabilize. To make it even more explicit: SUGGESTION 1. To gracefully isolate a router to avoid blackhole scenarios when there is a reload and possible long reconvergence times. Let me know if this addresses all your comments Thanks Padma Nits: > > In the abstract: > Change > “This document defines a bit (Host-bit)” > to > “This document defines a Host bit (H-bit)” > for consistency > And “is a non-transit router.”” - remove the spurious “. > > Section 8: > Where it says “beyond those already known in OSPF”, say OSPFv2. > >
- [Last-Call] Opsdir last call review of draft-ietf… Tim Chown via Datatracker
- Re: [Last-Call] Opsdir last call review of draft-… Padma Pillay-Esnault
- Re: [Last-Call] Opsdir last call review of draft-… Tim Chown
- Re: [Last-Call] Opsdir last call review of draft-… Padma Pillay-Esnault