5-17
Multiple Instance Spanning-Tree Operation
802.1s Multiple Spanning Tree Protocol (MSTP)
Note on MSTP
Rapid State
Transitions
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-compatible allows MSTP to
operate with rapid transitions disabled. The value of this parameter applies to
all ports on the switch. See the information on force-version on page 21.
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.
This section assumes that you have already:
1. Configured MSTP global parameters. This step involves configuring the
following:
• Required parameters for MST region identity:
Region Name: spanning-tree config-name
Region 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 9.
– The maximum number of hops before the MSTP BPDU is dis-
carded (default: 20)
spanning-tree max-hops
– Force-Version operation
spanning-tree force-version
–Forward Delay
spanning-tree forward-delay
– Hello Time (used if the switch operates as the root device.)
spanning-tree hello-time
– Maximum age to allow for STP packets before discarding
spanning-tree maximum-age
