Allied Telesis XS910/8, Manual

Page: 19 / 62

Chapter 1: Product Description
19
Examples with
Multiple Loop
Prevention
Switches
In examples shown in Figure 6, multiple AT-XS910/8 switches form links
and all switches are Loop Prevention enabled. Switch C has a lower MAC
address than Switch A and Switch B; Switch B has a lower MAC address
than Switch A.
First, these switches elect a root switch by comparing the MAC addresses.
In cases 1 and 2, Switch B is elected as a root switch; in case 3, Switch C
is elected as a root switch.
Then the root switch initiates Loop Prevention frames and non-root
switches update the frames and forward them. When detecting a loop, the
root switch runs the Loop Prevention algorithm to decide which port to
block, and blocks a port or ports to relieve the loop.
x
Figure 6. Multiple AT-XS910/8 Switches for Loop Prevention