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

[Bernard Aboba <aboba@internaut.com>]

> Even if the ND cache or transmission state is latent, packets could
> still be sent for DNA purposes of course, but we'd have to examine
> whether other traffic would be paused, sent or discarded (for example,
> if it takes a long time to do DNA, then VoIP packets are better
> dropped).

It has been pointed out to me that packets already in the queue aren't
salvagable if the host has changed subnets.  Typically the choice is
either to send them or discard them -- you can't go back and change the
headers after DNA completes, since that might require resegmentation.

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.

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.