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Chapter 10
Troubleshooting AppleTalk Connectivity
is further restricted to 127 hosts. Table 10.1 presents the differences between
AppleTalk phases one and two.
Table 10.1 presents AppleTalk phase two as being virtually unlimited in terms of
host addresses. This is due to the theoretical capability of AppleTalk to consider
cable range 165,279 as one network, with 253 hosts per single cable range
(cable range 11, for example). Thus, the true number of maximum nodes in an
AppleTalk network is approximately 16 million. Although possible, this is well
beyond the broadcast and physical limitations of most networks, and most cable
ranges do not span more than 10 digits (1019, for example).
A cable range is defined at an AppleTalk router, and it provides the network
portion of the address. In phase one, this range consists of a single number
(five, for example). In phase two, this number can span any sequential set
of numbers. For example, a valid network in phase two AppleTalk is 1017.
This range provides for 2,024 nodes. Note that there are no subnet masks or
other IP-style parameters.
AppleTalk Routing
By default, AppleTalk uses RTMP and ZIP, which are protocols that con-
tribute to AppleTalk's chatty reputation. RTMP updates are sent every 10
seconds; by default, routes are aged out after 20 seconds. This results in a
high volume of traffic and an extreme sensitivity to congestion--a route
announcement may not be sent due to other traffic.
T A B L E 1 0 . 1
Comparison of AppleTalk Phase One and AppleTalk Phase Two
AppleTalk Phase One
AppleTalk Phase Two
Number of network
addresses per
segment
1
65,279
Number of host ad-
dresses per network
254--127 servers, 127
hosts
253 per network ad-
dress, Virtually unlim-
ited
Number of zones per
network
1
255
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