Re: [Lsr] Benjamin Kaduk's No Objection on draft-ietf-ospf-ospfv2-hbit-11: (with COMMENT)

Benjamin Kaduk <kaduk@mit.edu> Thu, 05 December 2019 20:45 UTC

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Date: Thu, 5 Dec 2019 12:45:29 -0800
From: Benjamin Kaduk <kaduk@mit.edu>
To: Padma Pillay-Esnault <padma.ietf@gmail.com>
Cc: The IESG <iesg@ietf.org>, draft-ietf-ospf-ospfv2-hbit@ietf.org, Yingzhen Qu <yingzhen.ietf@gmail.com>, Alvaro Retana <aretana.ietf@gmail.com>, lsr-chairs@ietf.org, lsr@ietf.org
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Subject: Re: [Lsr] Benjamin Kaduk's No Objection on draft-ietf-ospf-ospfv2-hbit-11: (with COMMENT)
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On Wed, Dec 04, 2019 at 10:22:53AM -0800, Padma Pillay-Esnault wrote:
> Hi Ben
> 
> Thanks for your thorough review.
> 
> See below PPE for my comments
> 
> On Tue, Dec 3, 2019 at 5:45 PM Benjamin Kaduk via Datatracker <
> noreply@ietf.org> wrote:
> 
> > Benjamin Kaduk has entered the following ballot position for
> > draft-ietf-ospf-ospfv2-hbit-11: No Objection
> >
> > When responding, please keep the subject line intact and reply to all
> > email addresses included in the To and CC lines. (Feel free to cut this
> > introductory paragraph, however.)
> >
> >
> > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
> > for more information about IESG DISCUSS and COMMENT positions.
> >
> >
> > The document, along with other ballot positions, can be found here:
> > https://datatracker.ietf.org/doc/draft-ietf-ospf-ospfv2-hbit/
> >
> >
> >
> > ----------------------------------------------------------------------
> > COMMENT:
> > ----------------------------------------------------------------------
> >
> > Abstract
> >
> >    The Open Shortest Path First Version 2 (OSPFv2) does not have a
> >    mechanism for a node to repel transit traffic if it is on the
> >    shortest path.  This document defines a bit (Host-bit) that enables a
> >
> > nit: I suggest to add "protocol" after "(OSPFv2)" to match the definite
> > article "The".
> >
> > PPE - ok
> 
> 
> > Section 1
> >
> >    The OSPFv2 specifies a Shortest Path First (SPF) algorithm that
> >
> > (same nit about adding "protocol")
> >
> > PPE - ok
> 
> 
> >    This functionality is particularly useful for a number of use cases:
> >
> > nit: "this functionality" seems to refer to "the SPF algorithm that
> > identifies transit verticies based on their adjacencies", so I suggest
> > rewording to "such functionality would be useful" or "A mechanism to
> > move traffic away from the shortest path" or similar.
> >
> > PPE - ok will change as you suggest
> 
> Suggested NEW:
> "A mechanism to move traffic away from the shortest path is particularly
> useful for a number of use cases:"

Thanks!

> 
> > Section 4
> >
> > I suggest noting that the (lettered) sub-procedures of step (2) remain
> > unchanged.
> >
> > PPE - The original format of OSPF rfc2328 steps for SPF calculation was
> kept for clarity. Would a sentence to that effect work?

I think so.  Basically, if a reader treats "step (2)" as including the
lettered sub-procedures, then our replacement version has stripped off all
the sub-procedures and not replaced them.  So we need to tell the reader
that we don't mean to include the sub-procedures in what is being replaced.

> 
> 
> > Section 5
> >
> >    In normal operation, there is no guarantee that the RI LSA will reach
> >    all routers in an area in a timely manner, which may result in
> >    forwarding loops in partial deployments.  For example, if a new
> >    router joins an area, which previously had only H-bit capable routers
> >    with H-bit set then it may take some time for the RI to propagate to
> >    all routers.
> >
> > It's currently only implicit that this new router does not support the
> > H-bit; shall we make it explicit?
> >
> 
> PPE - ok
> 
> Suggested NEW:
>  If a new router without H-bit support joins an area, which previously had
> only H-bit capable routers
>  with H-bit set then it may take some time for the RI to propagate to all
> routers.
> 
> 
> 
> >    o  All routers supporting H-Bit MUST check all the RI LSAs of nodes
> >       in the area before actively running the modified SPF to account
> >       for the H-bit in order to verify that all routers are in routing
> >       capability.  If any router does not advertise the Host Router
> >
> > nit: the grammar here is a little wonky, particularly for "all routers
> > are in routing capability" but perhaps also for "to account for the
> > H-bit".
> >
> > PPE -  agree
> 
> Suggested NEW:
> All routers supporting H-Bit MUST check all the RI LSAs of nodes in the
> area before actively
> running the modified SPF in order to verify that all routers in the area
> support the H-bit capability.

Looks good.

> 
> Section 6
> >
> >    When calculating the path to an OSPF AS-External-LSA or NSSA-LSA
> >    [RFC3101] with a Type-2 metric, [...]
> >
> > nit: is this saying "calculating the path to [an LSA]"?  That's not a
> > usage I'm familiar with; can the AS-External-LSA or NSSA-LSA really
> > serve as a destination in this sense?
> >
> > PPE - suggest adding the word " prefix" which was implicit here.

Thanks!

> 
> > Section 7
> >
> > Thank you for phrasing this as "this document requests the IANA to
> > assign", since until these specific values are officially assigned we
> > are technically "squatting" on them.  (The respective registration
> > policies of Standards Action and IETF Review give us pretty good control
> > that nothing else is going to swoop in on them, though.)
> >
> >
> >
> Let me know if these changes address your comments

They look good, thanks again.

-Ben