HP 5400ZL User Manual
Page 140
Multiple Instance Spanning-Tree Operation
Configuring MSTP
■
Plan individual regions based on VLAN groupings. That is, plan on all
MSTP switches in a given region supporting the same set of VLANs. Within
each region, determine the VLAN membership for each spanning-tree
instance. (Each instance represents a single forwarding path for all VLANs
in that instance.)
■
Verify that there is one logical spanning-tree path through the following:
•
Any inter-regional links
•
Any IST or MST instance within a region
•
Any legacy (802.1D or 802.1w) switch or group of switches. (Where
multiple paths exist between an MST region and a legacy switch,
expect the CST to block all but one such path.)
■
Determine the root bridge and root port for each instance.
■
Determine the designated bridge and designated port for each LAN seg
ment.
■
Determine which VLANs to assign to each instance, and use port trunks
with 802.1Q VLAN tagging where separate links for separate VLANs would
result in a blocked link preventing communication between nodes on the
same VLAN. (Refer to “MSTP Operation with 802.1Q VLANs” on page 4
12.)
■
Identify the edge ports connected to end nodes and enable the admin
edge-port setting for these ports. Leave the admin-edge-port setting dis
abled for ports connected to another switch, a bridge, or a hub.
N o t e o n M S T P
Under some circumstances the rapid state transitions employed by MSTP can
R a p i d S t a t e
increase the rates of frame duplication and misordering in the switched LAN.
Tr a n s i t i o n s
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 4-23.
4-18