Spanning-Tree Operation

802.1s Multiple Spanning Tree Protocol (MSTP)

[ path-cost < auto 1..200000000 > ]

Assigns an individual port cost that the switch uses to determine which ports are forwarding ports in a given spanning tree. In the default configuration ( auto ) the switch determines a port’s path cost by the port’s type:

10 Mbps: 2000000

100 Mbps: 200000

1 Gbps: 20000

Refer to “Note on Path Cost” on page 5-19 for information on compatibility with devices running 802.1D STP for the path cost values (Default: Auto.).

point-to-point-mac < force-true force-false auto >

This parameter informs the switch of the type of device to which a specific port connects.

Force-True(default): Indicates a point-to-point link to a device such as a switch, bridge, or end-node. Force-False: Indicates a connection to a hub (which is a shared LAN segment).

Auto: Causes the switch to set Force-False on the port if it is not running at full duplex. (Connections to hubs are half-duplex.)

priority < 0..15 >

MSTP uses this parameter to determine the port(s) to use for forwarding. The port with the lowest priority number has the highest priority. The range is 0 to 240, and is configured by specifying a multiplier in the range of 0 -

15.For example, to enter a priority of 64 you would configure Priority with a multiplier of 4; that is, (4 x 16 = 64). Thus, the displayed default setting of 128 is derived from the default multiplier of 8. When you use the show spanning-treecommand options, the Priority appears as the result of the multiplier x 16, and not the multiplier itself. (Default: 128; configured multiplier = 8).

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