3Com Baseline 2226 Plus, User Manual

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50 C
HAPTER
4: C
ONFIGURING THE
S
WITCH
path is maintained between spanning
tree-compliant networked devices by:
■
Disabling redundant paths when the main
paths are operational.
■
Enabling redundant paths if the main paths
fail.
Spanning tree uses a distributed algorithm to
select a bridging device that serves as the root
of the spanning tree network. The bridging
device, known as the Root Bridge, generates
bridge protocol data units (BPDUs) on all ports
at a regular interval known as the Hello Time.
All other spanning tree-compliant devices on
the network have a designated Root Port. This
is the Port nearest the Root Bridge and it is
used for receiving the BPDUs initiated by the
Root Bridge. If a bridge does not get a Hello
BPDU after a predetermined interval, the bridge
assumes that the link to the Root Bridge is
down. This bridge will then initiate
negotiations with other bridges to reconfigure
the network to reestablish a valid network
topology.
After all the bridges on the network have
determined the configuration of their ports,
each bridge only forwards traffic between the
Root Port and the ports that are the Designated
Bridge Ports for each network segment. All
other ports are blocked, which means that they
are prevented from forwarding traffic.
To use spanning tree, choose enabled from the
drop State down menu, fill in the setup
parameters, and click
Apply .
Figure 33 Spanning Tree Screen