10/100 Fast Ethernet Switch User’s Guide
32 Switch Management
Illustration of STA
A simple illustration of three Bridges (or the Switch) connected in
a loop is depicted in Figure 5-1. In this example, you can
anticipate some major network problems if the STA assistance is
not applied. For instance, if Bridge 1 broadcasts a packet to
Bridge 2, Bridge 2 will broadcast it to Bridge 3, and Bridge 3 will
broadcast it to Bridge 1...and so on. The broadcast packet will be
passed indefinitely in a loop, causing a serious network failure.
To alleviate network loop problems, STA can be applied as shown
in Figure 5-2. In this example, STA breaks the loop by blocking
the connection between Bridge 1 and 2. The decision to block a
particular connection is based on the STA calculation of the most
current Bridge and Port settings. Now, if Bridge 1 broadcasts a
packet to Bridge 3, then Bridge 3 will broadcast it to Bridge 2 and
the broadcast will end there.
STA setup can be somewhat complex. Therefore, you are advised
to keep the default factory settings and STA will automatically
assign root bridges/ports and block loop connections. However, if
you need to customize the STA parameters, refer to Table 5-1.
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