ATL Telecom R1-SW Ethernet Switch - Manual (Page 264)

R1-SW24L2B User’s Manual
13-6
Ports of the learning state learn MAC addresses to transmit frames. Then, after forward delay
time is passed, the learning state becomes the forwarding state. Frames that are received before
ports become the forwarding state are discarded. After the forwarding, received frames are
transmitted through ports.
Ports of the disabled state do not participate in the spanning tree. These ports neither transmit
or receive BPDUs and do not transmit frames.
Selecting Path
The STP uses a spanning-tree algorithm to select one switch of a redundantly connected
network as the root of the spanning tree. The algorithm calculates the best loop-free path
through a switched Layer 2 network by assigning a role to each port based on the role of the
port in the active topology.
When two interfaces on a switch are part of a loop, the
spanning-tree port priority and path cost
settings determine which interface is put in the forwarding state and which is put in the
blocking state. The port priority value represents the location of an interface in the network
topology and how well it is located to pass traffic. The path cost value represents media speed.
Spanning tree forces redundant data paths into a standby (blocked) state. If a network segment
in the spanning tree fails and a redundant path exists, the spanning-tree algorithm recalculates
the spanning-tree topology and activates the standby path.