Changing Zone Names; Aging Out The Network Range - 3Com 4007 Implementation Manual

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HAPTER PPLE ALK OUTING
Changing Zone When you change the zone information for a network, all routers on the
Names segment must update their Zone Information Tables with the new
information. Although no AppleTalk mechanism forces routers to update
zone lists, you can successfully change the zones that are associated with
a network segment by aging out the existing network range, as described
in the following section.

Aging Out the Network Range

If you want to change the zone information for a segment and retain the
existing network range, you must age out the range from all routers on
the network. This practice ensures that all routers query for the new zone
information. This is necessary because after a zone has been acquired,
routers do not query for zone information until the network has been
aged out of their routing tables.
If you do not age out the network range, some routers may not remove
the network from their routing tables. Devices attached to these
networks are then unaware of the new zone information, which can
result in some users seeing the new zones in their Choosers, while others
see the old zones.
To age out the network range, you must prevent routers on the network
from sending RTMP messages that contain the network range for a
minimum amount of time, known as the ZIP bringback time. ZIP defines a
bringback time of 10 minutes.
During this time, all AppleTalk interfaces on the network segment are
brought down and cannot send or receive RTMP packets to confirm the
existence of the network in their RTMP tables. The unconfirmed network
ranges are then aged out of their routing tables; the associated zone
information for the network range is removed as well.