AppleTalk Internet Redesign (10/93)

Article Created: 5 October 1993

I have an internet redesign issue. I'm concerned about my strategy to
update the router definitions in my network.

Is it possible for the router/zone updating process to propagate bad zone
information after it is changed? If I update a zone list on a router is
the old table kept in other routers and forwarded as a part of normal
updating therefore maintaining this bad zone information? What exactly
prevents this from happening if anything?

What phenomenon on the network would cause ZIP storms between routers?

If I am changing my Internet wide zone lists what strategy should I follow
in updating the routers? Do I need to isolate each while I change it and
prevent it communication with others until they are all updated? If this
isn't possible do I have other choices?

Is it possible for normal RTMP updating between routers to propagate bad
network number entries that keep "updating around the network" when they no
longer describe a valid network entry? This assumes a router is redefined
to have a different network number setup for the ports that it seeds.

There is also a problem with zone names and zones appearing/disappearing in
the chooser.

I have a 6000 node network with hundreds of subnets. I want to change my
network zone tables from one that reflects a physical layout to a logical
one, but I'm concerned about how to implement a ZIP change on a subnet when
routers may be propagating bad zip information behind the changes for old
entries.

The Zone Information Protocol (ZIP) does not support dynamic network
changes. The prescribed method of updating a zone list is to temporarily
isolate the changing network from the internet, shut down all routers
directly connected to the changing network, and change the zone list in
each of the seed routers. Inside AppleTalk recommends the routers remain
down for approximately 10 minutes to allow the old zone list to age out of
all the other routers in the internet before being started again. If this
procedure is not followed, it is possible for old zone information to be
propagated after a change is made (depending on the complexity of the
change, this could cause ZIP storms between routers).

Inside AppleTalk alludes to a "future network management protocol" that
would provide the capability of changing the zone list of a network while
that network is active as a part of the internet. Unfortunately, such a
protocol hasn't been developed yet, so the aforementioned procedure is the
only way to properly implement a network change.

The Routing Table Maintenance Protocol (RTMP) would only be temporarily
impacted by a network change. The old network table entries would time out
and get deleted as the routers on the internet no longer heard from the
"old network" (Inside AppleTalk indicates this should take approximately 60
seconds).