[comp.protocols.appletalk] Routing Table size for FastPaths

BSCHMIDT@bnr.ca (Ben Schmidt, B.T.) (06/07/89)

Pieter,

I also would like to know what the routing and zone information table
size limits are in FastPath 2's, 2U's and 4's.  (Not to mention
GatorBoxes and other common AppleTalk routers...)

I believe I was given the number 128 by Kinetics for the FastPath 2.
Hence this would also suggest that a 64 zone limit might be a restriction
due to atalkad.  As well it seems possible that one might use up all
the zone information table space in a router using zones names of 32
in length, but still have room for routes in the routing table.  I wish
the router manufacturers would clearly state their routing and zone
table limits OR at least allow you to interrogate the router for
what space its allocating and how much is left!

As far as the FastPath 4, I was also told it would support "many"
zones.  This was guesstimated by my Kinetics contact at 500, but the
calculations to support it had not been done.  One wonders as well
what the impact of increasing the FP4 memory to 1Mb from its std.
1/2 Mb might be.

Finally as far as I understand AppleTalk routing, each router must
know about every other router on the internet.  Hence the routing
table and zone information table in each router on your internet must
be large enough to hold all the routes and zones for your entire
AppleTalk internet.

This requirement that each AppleTalk router not only know about every
net but also regularly broadcast its view of the "universe" leads to some
interesting traffic considerations.  For example an ethernet-backbone
based internet with 50 FastPaths will have at least 5 packets/sec on it
solely due to each FastPath generationg RTMP updates every 10 seconds,
as per the AppleTalk spec.  It could be more when the number of routes
exceeds that which can fit within a single RTMP packet.  I haven't
exceeded that limit yet.  Does Kinetics support multi-packet RTMP
broadcasts?  5 packets/sec isn't a lot - but remember it increases
with the router count and every ethernet node must do some minimal
processing on each RTMP broadcast packet, if only to ignore it.

AppleTalk is wonderful stuff, but it does seem to be prone to more
broadcasts than one would like and other irritants when scaled to the
size required at a large campus or institution.

Ben Schmidt

minshall@kinetics.UUCP (Greg Minshall) (06/10/89)

From article <Added.IYX4YE200Ui34dkE4E@andrew.cmu.edu>, by BSCHMIDT@bnr.ca (Ben  Schmidt, B.T.):
...
> ..  Does Kinetics support multi-packet RTMP
> broadcasts? ...

Yes.