🚀 go-pugleaf

In article <1941@ccnysci.UUCP>, alexis@ccnysci.UUCP (Alexis Rosen) writes:
>In article <29995@apple.Apple.COM> desnoyer@Apple.COM (Peter Desnoyers) writes:
>>    LocalTalk (through a bridge) - 138kbit/s
>>    EtherTalk (same wire)	 - 418kbit/s
>What I would like to know is why the hell we can't get better performance
>with EtherTalk on Macs? This performance is about one twenty-fifth the
>nominal speed of EtherNet. Not something to make the speed junky's pulse race.

Well, we've seen up to about 1.2mbit/s using vanilla EtherTalk drivers to
send & receive packets, so part of the problem is in the higher level
protocols.  The AppleTalk protocol stack (DDP in particular) is
tuned better for LocalTalk than for Ethernet.  For example, even though you
can send bigger packets on an Ethernet, EtherTalk can't use anything
over LocalTalk size, which is 576 bytes (+ headers).  That's a performance
hit right there.  Since AppleTalk as it stands has no notion of
fragmentation and reassembly, I don't see a simple way around this.  The
simplest thing (which is still pretty tricky) would probably be to
rewrite .ATP to be able to send ATP transactions in larger chunks, but this
might well break a lot of other stuff.  Sigh.  It'd be nice for future
versions of AppleTalk to have something along the lines of TCP/IP's
"mtu" and "maxseg" parameters...

--
Amanda Walker <amanda@intercon.UUCP>