3Com corebuilder 3500 Implementation Manual page 467

To change the associated zones for a network segment without changing
the segment's network range:
1 For any seed interfaces on the segment, use the
command to enter the new zone list for the existing network
modify
range. When prompted, enter the number of minutes to bring the seed
interface down, so that the interface does not send out RTMP updates.
ZIP defines a minimum bringback time of 10 minutes.
Although ZIP defines a minimum down time of 10 minutes, the exact
time required to ensure that the network range is aged from all routers
depends on the complexity and size of the network to which your
AppleTalk segment is attached.
2 For any nonseed interfaces attached to the segment for which you are
changing zone information, remove the interface, wait a minimum of
10 minutes (or a period of time appropriate to the size and complexity of
your network), then redefine the interface.
Changing the Network Range
This method involves assigning a new network range to the segment for
which you are changing zone information. This forces all routers on the
segment to query for the zone information when they receive the new
network range. The old information is removed from the ZIT when the
old network range is aged out of the RTMP tables.
To change the zone information for a network by assigning a new
network range to the segment, do the following:
1 Reconfigure any seed router interfaces connected to the segment with
the new network range and zone information. Because you are
specifying a new network range, you do not have to bring the seed
interfaces down.
2 For any nonseed interfaces attached to the segment for which you are
changing zone information, remove the interface, wait a minimum of
10 minutes (or a period of time appropriate to the size and complexity of
your network), then redefine the interface.
Although ZIP defines a minimum down time of 10 minutes, the exact
time required to ensure that the network range is aged from all routers
depends on the complexity and size of the network to which your
AppleTalk segment is attached.
The new network range is propagated throughout the network forcing all
routers to query for the new network's zone information.
AppleTalk Zones 467
appletalk interface