Operating Rules - HP procurve 8100fl series Management And Configuration Manual

N o t e
Problem:
An MST instance with two
separate (non-trunked)
links blocks a VLAN link.
Nodes 1 and 2 cannot
communicate because
MSTP is blocking the link.
Figure 9-4. Example of Using a Trunked Link To Support Multiple VLAN
Connectivity within the Same MST Instance
All switches in a region should be configured with the VLANs used in that
region, and all ports linking MSTP switches together should be members of
all VLANs in the region. Otherwise, the path to the root for a given VLAN will
be broken if MSTP selects a spanning tree through a link that does not include
that VLAN.

Operating Rules

All switches in a region must be configured with the same set of VLANs,
■
as well as the same MST configuration name and MST configuration
number.
Within a region, a VLAN can be allocated to either a single MSTI or to the
■
region's IST instance.
■ All switches in a region must have the same VID-to-MST instance and VID-
to-IST instance assignments.
There is one root MST switch per configured MST instance.
■
Spanning-Tree Operation
802.1s Multiple Spanning Tree Protocol (MSTP)
Solution:
Configure one trunked
link for the two VLAN
memberships.
Nodes 1 and 2 can communicate because the
MST instance sees the trunk as a single link and
802.1Q (tagged) VLANs enable the use of one
(trunked) link for both VLANs.
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