Allied Telesis 8100S Series - Manual (Page 55)

Stack Installation Guide for 8100S Series Switches
55
Stacking Port Topologies
The switches are connected together with the S1 and S2 ports in the
management panels, and the stacking cables that come with the units.
There are two wiring configurations. The first topology is called the duplex-
chain topology. This topology connects the switches with a single
pathway. A stacking port on one switch is connected to a stacking port in
the next switch, which is connected to the next switch, and so on. The
connections crossover to different stacking ports on the switches, such
that the S1 port in one switch connects to the S2 port in the next switch.
Caution
The stack will not function if the connections to the S1 and S2
stacking ports do not crossover on the switches. If two S1 ports or
two S2 ports are connected together, the switches will not form a
stack and instead operate as stand-alone devices.
The second topology, the duplex-ring topology, is similar to the duplex-
chain, except that the unused stacking ports on the end switches of the
stack are connected together to form a physical loop, creating two
pathways through the stack. An example of both topologies is shown in
Figure 16 on page 56.
Although the topologies are the same in terms of network speed and
performance, the duplex-ring topology is the recommended wiring
configuration because of the secondary path it provides through the
stacking ports. The two pathways protect the switches of the stack against
the loss of communications due to a failure of a stacking port, cable, or
switch.