Illustration Of Sta - D-Link DES-3225G User Manual

24-port NWay Ethernet Switch User's Guide

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.
36 Switch Management Concepts