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seed router per network cable segment. It may sometimes be desirable for redundancy to have several seed routers on a segment. This is acceptable as long as all seed routers on the segment are seeding the same network number/range.
Unlike TCP/IP, AppleTalk workstations do not have fixed network/node addresses that need to be configured. Instead, a workstation gets a network number from the router(s) on the segment it is connected to, and picks an unused address for its node number through a process called probing.
Probing
When a device comes up on a
When a device comes up on an extended AppleTalk network, it will set its network number randomly to one of the numbers in the range seeded on the network, and then try to claim a node address. It does this by sending out a packet to all other nodes on its segment asking whether the node address is already in use. If another node using the same number in the network range responds, the original node will randomly select another network number and node address value and try again.
Zones
While network numbers/ranges logically group devices together according to which network segment they are connected to, AppleTalk zones provide a way of creating groupings which can correspond to any concept a network administrator cares to use. This could be the department the devices are used in, the physical location of the devices, or some other method of categoriza- tion.
Zones are configured into a router by an administrator, and are logically tied to a segment and its network number/range by the router. However, the same zone names can be used on different segments. This gives an administrator the opportunity to make zone names represent groups of devices which are on more than one segment. A
Once a device has successfully claimed an address, it contacts a router on its segment and asks for a list of zones for the segment. Unless it has been config- ured to pick one of the other zones, it will use the “default zone” which is returned by the router.
