3Com 3CRWEASYA73 / WL-575 User Manual page 94

C 5: S C
HAPTER YSTEM ONFIGURATION
Figure 41 Spanning Tree Protocol
Spanning Tree Protocol – STP uses a distributed algorithm to select a bridging
device (STP-compliant switch, bridge or router) that serves as the root of the
spanning tree network. It selects a root port on each bridging device (except for
the root device) which incurs the lowest path cost when forwarding a packet
from that device to the root device. Then it selects a designated bridging device
from each LAN which incurs the lowest path cost when forwarding a packet from
that LAN to the root device. All ports connected to designated bridging devices
are assigned as designated ports. After determining the lowest cost spanning
tree, it enables all root ports and designated ports, and disables all other ports.
Network packets are therefore only forwarded between root ports and
designated ports, eliminating any possible network loops.
Once a stable network topology has been established, all bridges listen for Hello
BPDUs (Bridge Protocol Data Units) transmitted from the root bridge. If a bridge
does not get a Hello BPDU after a predefined interval (Maximum Age), 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.
Bridge – Enables/disables STP on the wireless bridge or repeater.
(Default: Disabled)
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