KB.15.15

Enables automatic identification of edge ports for faster convergence. When

enabled, the port looks for BPDUs for the first 3 seconds. If there are none, the port

is classified as an edge port and immediately starts forwarding packets. If BPDUs

are seen on the port, the port is classified as a non‐edge port and normal STP

operation commences on that port.

If admin-edge-port is enabled for a port, the setting for auto-edge-port is

ignored whether set to yes or no.

If admin-edge-port is set to no, and auto-edge-port has not been disabled

(set to no), then the auto-edge-port setting controls the behavior of the port.

NOTE: See“CAUTION” (page 122). Requires thorough knowledge of IEEE

802.1D/w/s standards and operation.

Default: Enabled

The no form of this command disables auto-edge-port operation on the specified

ports.

Specifying the interval between BPDU transmissions

Syntax:

spanning-tree port-list hello-time [ global | 1 - 10 ]

When the switch is the CIST root, this parameter specifies the interval (in seconds)

between periodic BPDU transmissions by the designated ports. This interval also

applies to all ports in all switches downstream from each port in the port-list.

A setting of global indicates that the ports in port-list on the CIST root are

using the value set by the global spanning tree hello-time value.

When a given switch X is not the CIST root, the per-port hello-time for all active

ports on switch X is propagated from the CIST root, and is the same as the

hello-time in use on the CIST root port in the currently active path from switch

X to the CIST root. When switch X is not the CIST root, then the upstream CIST root's

port hello-time setting overrides the hello-time setting configured on switch

Default Per-Port setting: Use Global.

Default Global Hello-Time: 2.

Forcing a port to send RST/MST BPDUs

Syntax:

spanning-tree port-list mcheck

Forces a port to send RST/MST BPDUs for 3 seconds. This tests whether all STP

bridges on the attached LAN have been removed and the port can migrate to native

MSTP mode and use RST/MST BPDUs for transmission.

Determining which ports are forwarding ports by assigning port cost

Syntax:

spanning-tree port-list 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

84 Multiple instance spanning tree operation