N o t e o n M S T P R a p i d S t a t e Tr a n s i t i o n s

Spanning-Tree Operation

802.1s Multiple Spanning Tree Protocol (MSTP)

Under some circumstances the rapid state transitions employed by MSTP (and RSTP) can increase the rates of frame duplication and misordering in the switched LAN. To allow MSTP switches to support applications and protocols that may be sensitive to frame duplication and misordering, setting the Force Protocol Version (force-version) parameter to stp-compatibleallows MSTP to operate with rapid transitions disabled. The value of this parameter applies to all ports on the switch. See the information on force-versionon page 62.

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Steps for Configuring MSTP

This section outlines the general steps for configuring MSTP operation in your network, and assumes you have already planned and configured the VLANs you want MSTP to use. The actual MSTP parameter descriptions are in the following sections.

The switch supports MSTP configuration through the CLI. After you specify MSTP and reboot the switch as described above, the switch removes the Spanning Tree option from the Menu interface. If you later reconfigure the switch to use STP or RSTP, the switch returns the Spanning Tree option to the Menu interface.

This section assumes that you have already

1.Configured the MSTP operation mode. This specifies MSTP as the span­ ning tree operating mode. Changing the current MSTP operation mode requires you to save the change and reboot to activate the selection. spanning-treeprotocol-version < stp rstp mstp >

2.Configure MSTP global parameters. This step involves configuring the following:

• Required parameters for MST region identity:

Region Name: spanning-tree config-nameRegion Revision Number: spanning-tree config revision

Optional MSTP parameter changes for region settings:

ProCurve recommends that you leave these parameters at their default settings for most networks. Refer to the “Caution” on page 49.

The maximum number of hops before the MSTP BPDU is dis­ carded (default: 20)

spanning-tree max-hops

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