KB.15.15

Sets the time the switch waits between transitions from listening to learning and

from learning to forwarding states.

Range: 4 - 30

Default: 15 seconds

Setting spanning tree to operate in 802. ID legacy mode

Syntax:

[no] spanning-tree legacy-mode

Forces spanning tree to operate in legacy (802.!D) mode.

Default: MSTP-operation.

The no form of this command returns the switch to the default 802.1s native mode

(MSTP-operation.)

Setting spanning tree to operate with 802. ID legacy path cost values

Syntax:

spanning-tree legacy-path-cost

Forces spanning tree to operate with legacy (802.!D) path cost values.

Default: 802.1t.

The no form of the command returns the switch to the default 802.1t (not legacy)

path cost values.

Specifying the time interval between BPDU transmissions

Syntax:

spanning-tree hello-time 1..10

If MSTP is running and the switch is operating as the CIST (Common and Internal

Spanning Tree) root for your network, this command specifies the time in seconds

between transmissions of BPDUs for all ports on the switch configured with the

Global option (the default). This parameter applies in MSTP, RSTP and STP modes.

During MSTP operation, you can override this global setting on a per-port basis

with this command: spanning-tree port-list hello-time 1..10 .

Default: 2 seconds.

Setting the hop limit for BPDUs

Syntax:

spanning-tree max-hops hop-count

Resets the number of hops allowed for BPDUs in an MST region. When an MSTP

switch receives a BPDU, it decrements the hop-count setting the BPDU carries. If the

hop-count reaches zero, the receiving switch drops the BPDU.

Note that the switch does not change the message-age and maximum-age data

carried in the BPDU as it moves through the MST region and is propagated to other

regions.

Range: 1 - 40

Default: 20

Configuring MSTP operation mode and global settings 81