Re: [DNA-BOF] Re: Sending while DNA is in progress...

[Bernard Aboba <aboba@internaut.com>]

> The problem here is that the link layer address of the router is not
> known.  If it is known, then it may make sense to dispatch packets
> even if they are malformed.

I think that the link layer address of the router can be learned various
ways.  One way is through DNA.  But it is also possible to confirm that
the default gateway remains the same via continued reception of packets
originating from it.

> > If the host remains on the same subnet, the packets can and should be
> > sent. If the host has changed subnets, then no packets in the queue can be
> > delivered successfully.
>
> What comes to the same subnet case, I concur.  What comes to the
> changed subnet case, if the host has the new router's link layer
> address, it sometimes may make sense to dispatch the packets, as
> I argued above.

I think I agree.  There isn't much downside to doing this if it is
necessary to either send the packets or to discard them.  If the host has
changed subnets, sending the packets will deliver them to a MAC address
that no router is listening on.  But if the headers can't be rewritten
they would have to be discarded anyway.  So there's no downside -- might
as well send them.

> > As a result, continuing to send enqueued packets under the assumption
> > that the subnet remains the same has no downside, though it might make
> > sense to suspend the addition of packets to the send queue, pending completion
> > of DNA, so that they could be sure to acquire the correct headers.
> > Latency sensitive applications such as VOIP might be an exception to this.
>
> Do we need to consider the excess traffic in the case of dispatching
> packets that cannot be delivered succesfully?  If not, I think we agree.

In some situations I suppose this might be an issue (e.g. GPRS).  But I
don't think it is much of a concern on wireless LANs.