krauskpf@uxe.cso.uiuc.edu (01/01/88)
For comment:
How will EtherTalk broadcast packets affect Ethernet?
1. AppleTalk over Ethernet, known as EtherTalk, has a registered Ethernet
packet type of Hex 809B. Your network analyzer probably doesn't
recognize this one yet, but you will want it soon.
2. RTMP is the AppleTalk routing information scheme. It calls for a broadcast
packet every 10 seconds. We can live with this one, we know other routers
do this, but what interval would you like to encourage Apple to use? I
would like to see these packets closer to one minute apart.
3. Look out for AARP broadcasts! Apple has a registered AppleTalk Address
Resolution Protocol (AARP) packet type for Ethernet (Hex 80F3) and the
packet format looks a lot like ARP. There is a special broadcast packet
under AARP called a "probe" which prompted this warning message.
When EtherTalk is initialized (machine is booted), an EtherTalk node must
defend its unique 8-bit node number. Probe packets are sent out to try
to identify any machine with a matching node number. If no machine
responds, then the number is assumed to be unique.
Here's the kicker: The official EtherTalk specification calls for 20
retries of this broadcast packet spaced at intervals of 1/30th of a
second. Measurements confirm this is true for all of the EtherTalk
implementations that we have. So, you get a 20 packet broadcast storm
every time a Mac is booted.
What effect will this have on our networks? What about when there are 100
Macs on the same physical wire as your Suns? This obviously is of some
concern because we get bug reports from people who have noticed. Our
problem is that EtherTalk sometimes chooses to defend its node number when
our NCSA Telnet application is launched. Then we get blamed for an EtherTalk
problem. Note for Ethernet snoopers: If the packet type is 80F3 or 809B,
then we didn't generate it. We only generate IP (0800) and ARP (0806)
packet types.
Kinetics helped with the original EtherTalk spec, but I improperly flamed
Kinetics in an earlier posting. Sorry about that. Apple publishes the spec
which says 20 retries, 1/30 second interval.
Tim Krauskopf timk@ncsa.uiuc.edu (ARPA)
National Center for Supercomputing Applications 14013@ncsavmsa (BITNET)
(217)244-0638jim@b-mrda (01/03/88)
Is the Ethertalk spec available ? APDA ? Apple ? I have major problems with Ethertalk. What do you do when the 254th device is added to the network and you have 10 more waiting ? jim sadler 206-656-5422 hpubvwa!b-mrda!jim P.O. Box 3707 MS 6R-24 Seattle, Wa. USA 98124 Any opinions expressed are mine and mine only and not that of my employer. Also add in whatever else should be said at this point.
krauskpf@uxe.cso.uiuc.edu (01/11/88)
I think you have to go through Apple technical support. APDA does not have them (yet). I know of no current extension to support more than 254 nodes without a bridge. Tim Krauskopf timk@ncsa.uiuc.edu NCSA