[core] TCP, UDP, Proxy and Observe

[Jim Schaad <[e-mail]>]

I have been sketching out what my TCP/UDP and UDP/TCP proxy code would look
like and I am having a problem deciding what should be done for the observe
option.

If you have the case of Client->UDP->Proxy->UDP->Server, then dealing with
out of order observations can be dealt with in the following ways:

1. Pass them through unchanged or subtract a constant from the observer
value.  This pushes the problem of out of order observes onto the client.
The proxy would save the high water content.
2. Filter on observe value so that out of order transmissions are
suppressed.
3. Keep out of order items around for a while and see if the out of order
items show up and transmit them back as in order.  I missing items do not
show up until the time out, then suppress the out of order items.
4. Reorder the numbers so that things are seen in the wrong order by the
client.  (Obviously a wrong answer.)

I assumed that 1 was the correct answer and deal with things that way.

Now I come to the question of Client->TCP->Proxy->UDP->Server.  Since the
observe value is now to be ignored or removed, the first option above will
no longer work and I am not sure which the remaining options is the correct
one to do.  Does a reliable transmission protocol mean that we should
suppress items?

Jim