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

From: Datatracker on behalf of Eric Rescorla <[email-masked]>
Date: Thu, 07 Mar 2019 06:08:00 -0800

Eric Rescorla has entered the following ballot position for
draft-ietf-mpls-sfc-05: Discuss

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DISCUSS:
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Rich version of this review at:
https://mozphab-ietf.devsvcdev.mozaws.net/D5624

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?

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COMMENT:
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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.

---

From: "Adrian Farrel" <[email-masked]>
Date: Thu, 7 Mar 2019 15:42:07 -0000

Thanks Ekr, that is an exceptionally good catch.

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.

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.

Yes. Easy addition to Section 15

---

From: Eric Rescorla <[email-masked]>
Date: Thu, 7 Mar 2019 07:50:00 -0800

> Thanks Ekr, that is an exceptionally good catch.

Glad to be able to add value :)

> 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