Stp - Planet GRT-504 User Manual

GRT-504 4-Wire G.SHDSL.bis Firewall Router User's Manual

6.2.5 STP

Click STP can disable or enable the bridge STP mode.
STP (Spanning-Tree Protocol) defined in the IEEE 802.1D, is a link management protocol that
provides path redundancy while preventing undesirable loops in the network. For an Ethernet
network to function properly, only one active path can exist between two stations.
Multiple active paths between stations cause loops in the network. If a loop exists in the network
topology, the potential exists for duplication of messages. When loops occur, some switches see
stations appear on both sides of the switch. This condition confuses the forwarding algorithm and
allows duplicate frames to be forwarded.
To provide path redundancy, Spanning-Tree Protocol defines a tree that spans all switches in an
extended network. Spanning-Tree Protocol forces certain redundant data paths into a standby
(blocked) state. If one network segment in the Spanning-Tree Protocol becomes unreachable, or if
Spanning-Tree Protocol costs change, the spanning-tree algorithm reconfigures the spanning-tree
topology and reestablishes the link by activating the standby path.
Spanning-Tree Protocol operation is transparent to end stations, which are unaware whether they
are connected to a single LAN segment or a switched LAN of multiple segments.
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