Re: [Int-area] WGLC on draft-ietf-intarea-frag-fragile-05

[Tom Herbert <[e-mail]>]

Hello. I have a couple of comments:

>From the draft:
"Middle boxes SHOULD process IP fragments in a manner that is
compliant with RFC 791 and RFC 8200.  In many cases, middle boxes must
maintain state in order to achieve this goal."

This requirement is confusing to me on several accounts. First of all,
there are a lot of requirements about fragmentation in both RFC791 and
RFC8200, including some MUSTs. This requirement seems to be updating
and possibly relaxing some of those requirements, but is not specific.
This seems ambiguous as a normative requirement.

Secondly, the only specified interaction between fragmentation and
intermediate nodes is that routers can fragment packets in IPv4. Other
than that, a middlebox that complies with RFC791 and RFC8200 does not
process or consider fragmentation of packets. Given that, it's unclear
to me why middle boxes would need to maintain state to be protocol
compliant. It's possible that the implicit exception of the
requirement is that middleboxes might perform "in-network reassembly"
or "virtual reassemlby" which would require state. If that is indeed
the case then the requirements for the mechanisms should be spelled
out.

For stateless load balancing (described in section 4.4), the IPv6 flow
label obviates the need for DPI. It is sufficient to hash over the
three tuple <saddr, daddr, flow label> to get good load balancing. All
major OSes have been updated to set flow labels, and there are devices
that already support this. IMO, the draft should make using flow label
for stateless load balancing a SHOULD.

Tom

On Mon, Jan 14, 2019 at 11:55 AM Joel M. Halpern <[e-mail]> wrote:
>
> I have re-read this document.  I think it is a useful document that
> captures that state of a complex tradeoff and makes effective
> recommendations. I support publishing it as a BCP.
>
> If the authors make further additions, adding a mention of ECMP as a
> particular case of stateless load balancers might further improve the
> document.
>
> Yours,
> Joel
>
> On 1/14/19 1:13 PM, Wassim Haddad wrote:
> > Dear all,
> >
> > This email starts an Int-Area WG Last Call on the latest version of "IP Fragmentation Considered Fragile” draft:
> >
> > https://tools.ietf.org/html/draft-ietf-intarea-frag-fragile-05
> >
> > Please respond to this email to support the document and/or send comments by 2019-01-28.
> >
> > Please indicate if you are personally aware of any IPR that applies to draft-ietf-intarea-frag-fragile-xx?
> > If so, has this IPR been disclosed in compliance with IETF IPR rules?
> >
> >
> > Regards,
> >
> > Juan & Wassim
> > _______________________________________________
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> >
>
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