Brian,
On 6/25/11 9:06 PM, Brian E Carpenter wrote:
> Hi,
>
> The discussion Jari's issue has died down, so I'd like to propose some
> revised text:
>
> A node that forwards a flow whose flow label value in arriving
> packets is zero MAY change the flow label value. In that case, it is
> RECOMMENDED that the forwarding node sets the flow label field for a
> flow to a uniformly distributed value as just described for source
> nodes.
> o The same considerations apply as to source hosts setting the flow
> label; in particular, the preferred case is that a flow is defined
> by the 5-tuple. However, there are cases in which the complete
> 5-tuple for all packets is not readily available to a forwarding
> node, in particular for fragmented packets. In such cases a flow
> can be defined by fewer IPv6 header fields, typically using only
> the 2-tuple {dest addr, source addr}. A forwarding node
> implementation MAY use this 2-tuple in all cases.
>
> [BC: this version indicates the problem that Jari discovered, but is
> agnostic on the question of whether a router could or should solve it
> by reassembling the fragmented packet.]
>
> o This option, if implemented, would presumably be used by first-hop
> or ingress routers. It might place a considerable per-packet
> processing load on them, even if they adopted a stateless method
> of flow identification and label assignment. This is why the
> principal recommendation is that the source host should set the
> label.
> o The deployment of this option MUST be consistent with [RFC4311].
>
> [BC: This last sentence is to cover Jari's point about a router knowing it's
> appropriate for it to set the label.]
>
> Comments? If not, I will post the draft in a day or two.]
These changes look fine to me.
Regards,
Brian
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