I didn't hear the presentation since I was sick. But yes, the draft
analyses all those ideas and rejects them - the surviving proposal
is to use the PHB ID. I will comment on that in response to Steve's
message.
The pseudorandom case works for intserv and is irrelevant to diffserv.
Brian
Jun-ichiro itojun Hagino wrote:
>
> >The traffic class field is not enough. If you have to re-classify traffic at
> >an administrative boundary, then by definition at that point the traffic class
> >field is inadequate; you need more information. The advantage that IPv6 has
> >is that even when the header is partly hidden by IPSEC, the flow label is
> >available to carry additional semantics. The actual proposal is to use the
> >PHB identifier which has end to end semantics.
>
> I heard the presentation differently. in IETF51 presentation Alex
> Conta made the following proposals, at least:
> - putting PHB value
> not trustworthy.
> - putting total extension header length
> if the originator lies about the value, intermediate routers
> can go panic.
> - putting port/addr/whatever encoded
> if the originator lies about the value, theft-of-service
> happens.
> none of these values are trustworthy, since originator can lie about
> those. because these values are not trustworthy, intermediate routers
> need to get those values by normal ways (by chasing extension header
> chain, or whatevr), and therefore, flow label value is just wasted.
>
> I particularly don't like the idea of putting total extension header
> length. as soon as it gets deployed bad guys can mount various attacks.
>
> So, back to my original posting, I vote for end-to-end pseudorandom
> 20bit value. intermediate router MAY use it to hash the traffic,
> that's all.
>
> itojun
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