Installation guide

5-7
AppleTalk Access Problems
Performance Problems
Introduction
It is possible that AppleTalk connections can be established, but performance is sluggish
or unreliable. Some symptoms of this are long file transfer times or inability to access
some services on the network. These problems are usually due to the slower data rates of
remote connections. We recommend that remote AppleTalk connections by means of the
access server run at rates of 9600 baud or higher. Aside from this solution of running at
higher data rates (that is, faster modems and/or modems using compression), factors
discussed in the next two sections should be checked.
Verify Unique AppleTalk Addresses
It is essential that all nodes running AppleTalk on the network have unique AppleTalk
addresses. If two nodes incorrectly acquire the same AppleTalk address (for example, due
to temporary network partition), then many problems can follow, some of which may
appear as performance problems. Using a management tool, verify that no other device is
using the same address as your connection.
It is also essential that all AppleTalk networks connected into an Internet have unique,
nonoverlapping network ranges. If this requirement is broken, traffic will be routed
incorrectly. This problem may surface as an inability to access services on another
network or as performance degradation. Verify that all AppleTalk networks that are
internetworked have unique network ranges.
Verify Protocol Retransmission Timeouts
Verify that the reliable transport protocols on the attached hosts and network servers are
estimating round-trip time when determining retransmission timeouts. If the transport
protocols use fixed timeouts, then they are likely to retransmit too soon when one link in
the connection is slow. This causes redundant retransmission, which wastes buffer space
and bandwidth, exacerbating the problem on the slow link. If the retransmission timeout is
set using a round-trip time estimate, these redundant retransmissions can be avoided,
resulting in much improved performance.