DSL link aggregation?

[Billy Crook]

Back for more eh?

On Fri, May 9, 2008 at 12:27 PM, Ed Allen <era at jimani.com> wrote:
>        Hardly worth wading through 150K because you wanted to point out that
>        FTP has been switched to TCP.

"Has been switched?"  Who flipped the switch? It's been a good 20 or
more years since TCP existed.  You can grep that 150k and see no
mention of UDP.  Some browsers even afford one the newfangled luxury
of a hotkey like, say, [Ctrl]+[F] where a user could use the computer
to search through their current document for a string.  However, a
machine that's not yet been 'upgraded' to support TCP, might not have
that fancy stuff, so maybe there's a sequence of flashing lights and
rotor switches that does the same.

>        Any other reason you think I should spend time reading that ?

Yes.  You needed a refresher, or were thinking of TFTP, which is not
FTP, but its own protocol typically used for link local file transfers
for hardware configuration or network booting (and not FTP).  There is
also an obscure protocol, UFTP, which is for broadcast and multicast.

>>> so FTP software reassembles out of order packets coming from different
>>> addresses constantly.

>> A TCP stack does that too.  http://www.faqs.org/rfcs/rfc793.html (Page
>> 4, Section: Reliability)

>        TCP acks each packet.  UDP is "send it and hope it gets there".

Uh huh. TCP stack "reassembles out of order packets" like you said FTP
did.  FTP however does not, because its packets are always in the
right order thanks to the TCP stack.

>        Even so I do not see a problem with sending alternate packets through
>        two IP addresses for outgoing as the ACKs will choose one to reply through
>        ignoring the other as a "more expensive" route.

You will if close Outlook and try it.  The ACKs won't choose anything.
 The destination machine will send an ack back to the IP that sent
whatever it's acknowledging.

> --
> Ed Allen