Alex,
The problem is that any such association is pretty much likely
to disappear across ISP/ISP boundaries, unless there is a global
standard for the semantics.
Brian
Alex Conta wrote:
>
> Brian,
>
> Brian E Carpenter wrote:
> > [...]
> > e) the only way I can see to do this is to compress port # and protocol #
> > information into the flow label.
> > [...]
> >
> > Brian
>
> Brian,
>
> This would allow any router on the path of a packet to apply the same
> 5-tuple
> classification rules, which is a nice feature.
>
> But, I am not sure why you exclude other ways, like associating a
> particular
> value to the 5-tuple, ala MPLS, and have all downstream routers "know"
> and
> classify based on that "known" value.
>
> As classification is done for practical purposes to place packets in
> distinct processing queues, I have mixed thoughts about the practicality
> of
> having both source and destination port numbers, and as a matter of fact
> the
> 5-tuple for that purpose. I wonder in fact, if one would have a straight
> answer
> on how many router implementations, including IPv4 ones, do per flow
> (5-tuple)
> queuing today, or plan to have that in the future.
>
> Alex
>
> >
> > Christian Huitema wrote:
> > >
> > > Brian,
> > >
> > > I am a bit puzzled by your reference to the 5 tuple as "enabling diffserv."
> > > I think you have a model there in which the diffserv bits are set by some
> > > intermediate router, after examining the "5 tuple" of the packet. In this
> > > context, the five-tuple works somewhat. But it does not work well with IPSEC
> > > (ports are hidden), it does not work well with floating port applications
> > > such as VoIP, and it leads to some interesting header manipulation when we
> > > encounter stacks of IPv6 headers.
> > >
> > > There are at least two other ways to "enable diffserv." One way would be to
> > > just let the hosts set the diffserv bits, and then let the intermediate
> > > router do accounting, charging, and maybe rationing. Another way is to use
> > > RSVP to convey the requested quality of service, and the user credentials,
> > > to the intermediate routers; then, the flow-id can be use for flow
> > > classification, and the intermediate routers can on this basis set the
> > > diffserv bits however they see fit.
> > >
> > > -- Christian Huitema
> >>[....]
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