Re: [mpls] Eric Rescorla's Discuss on draft-ietf-mpls-sfc-05: (with DISCUSS and COMMENT)

Eric Rescorla <ekr@rtfm.com> Thu, 07 March 2019 15:50 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Thu, 7 Mar 2019 07:50:00 -0800
Message-ID: <CABcZeBONCoKrgPdcGzLhxEMd10whyxL3DiZYVxGGX3=-4ZSJrw@mail.gmail.com>
To: Adrian Farrel <adrian@olddog.co.uk>
Cc: The IESG <iesg@ietf.org>, mpls@ietf.org, mpls-chairs <mpls-chairs@ietf.org>, draft-ietf-mpls-sfc@ietf.org
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Subject: Re: [mpls] Eric Rescorla's Discuss on draft-ietf-mpls-sfc-05: (with DISCUSS and COMMENT)
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On Thu, Mar 7, 2019 at 7:42 AM Adrian Farrel <adrian@olddog.co.uk> wrote:

> Thanks Ekr, that is an exceptionally good catch.
>

Glad to be able to add value :)


> It is both a simple problem and a real problem.
>
> A fix is going to take some thought and at least a few words.
>
> At a quick glance, I think the issue would at least get caught when an
> attempt to use the metadata was made (the index would not find an entry).
> That would cause an error to be flagged.
>
> But there are "update" cases that would not work.
>

Thanks. I'll probably be gone when this comes back, but I trust my
successors
to handle this (also, I don't think I have any special expertise here on how
to fix this; I just happened to notice it).

-Ekr


> Adrian
>
> > DISCUSS:
> >
> > I have what may be a simple question or a real interop problem,
> > as noted below. Hopefully it's the former and we can resolve it quickly.
> >
> > DETAIL
> > S 13.
> >         and defined in [RFC8300].
> >
> >      Metadata:  The actual metadata formatted as described in whatever
> >         document defines the metadata.  This field is end-padded with
> zero
> >         to three octets of zeroes to take it up to a four octet boundary.
> >
> > What happens if the packet gets lost? Is there an ACK? How often
> > should I send it?
> >
> >
> > COMMENT:
> >
> > S 12.1.
> >          ---------------
> >
> >                      Figure 4: The MPLS SFC Metadata Label
> >
> >      The Metadata Label value is an index into a table of metadata that
> is
> >      programmed into the network using in-band or out-of-band mechanisms.
> >
> > You note below that the network needs to be secure. You should also
> > note that access to this table needs to be secure.
>
> Yes. Easy addition to Section 15
>
>