Re: Flow label versus Extension header - protocol itself

[Greg Daley <greg.daley@eng.monash.edu.au>]

Hi Erik,

Erik Nordmark wrote:
[cut]
> > > And when switching to a different locator pair, and some flow 
> > > signaling is used, one would need to do the flow signaling for that 
> > > locator pair in any case. So using a different flow label for the 
> > > different locator pair shouldn't be much of an issue.
> >
> >
> >
> > I guess you'd only want to do the signalling when you had to:
> >
> > You wouldn't want to require signalling (or a new label)
> > for every locator pair change, if the label was receiver unique.
>
>
> By "signaling" I was referring to things like RSVP and NSIS. Those would 
> need to be triggered for every new <source IP, dest IP, flow label> 
> combination that needs whatever QoS is used. Thus if such protocols are 
> used before there is a change to a different locator pair, they would 
> need to be triggered for every new locator pair that is used for that 
> communication. And there doesn't seem to be a need to use the same flow 
> label across those reservations.

Indeed.

Since the device is on a new path, passing the receiver allocated
flow-label to the path signalling system would probably work OK.
If it doesn't, the sender will allocate a label (maybe the original
label from the original path), and it will be added to the set.

Where new labels are chosen, the <source IP, dest IP, flow label>
will need to be signalled to the peer before packets begin to use the
path (which may be OK, considering the order of the operations detailed
above).

Greg