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Cisco Systems IntelligentGigabit Ethernet Switch Modules for the IBM BladeCenter, Software Configuration Guide
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Chapter10 Configuring MSTP
Configuring MSTP Features
Default MSTP ConfigurationTable10-3 shows th e default MSTP configuration.
For information about the supported number of spanning-tree instances, see the “Supported
Spanning-Tree Instances” section on page 9-9.
MSTP Configuration GuidelinesThese are the configuration guidelines for MSTP:
•When you enable MST by using the spanning-tree mode mst global configuration command, RSTP
is automatically enabled.
•For two or more switches to be in the same MST region, they must have the same VLAN- to-instance
map, the same configuration revision number, and the same name.
•The switch supports up to 16 MST instances. The number of VLANs that can be mapped to a
particular MST instance is unlimited.
•PVST+, rapid PVST+, and MSTP are supported, but only one version can be active at any time. (For
example, all VLANs run PVST+, all VLANs run rapid PVST+, or all VLAN s run MSTP.) For more
information, see the “Spanning-Tree Interoperability and Backward Compatibility” section on
page 9-10.
•VTP propagation of the MST configuration is not supported. However, you can manually configure
the MST configuration (region name, revision number, and VLAN-to-instance map ping) on each
switch within the MST region by using the command-line interface (CLI) or through the SNMP
support.
•For load balancing across redundant paths in the network to work, a ll VLAN-to-instance mapping
assignments must match; otherwise, all traffic flows on a single link.
Table10-3 Default MSTP Configuration
Feature Default Setting
Spanning-tree mode PVST+ (Rapid PVST+ and MSTP are disabled).
Switch priority (configurable on a per-CIST interface basis) 32768.
Spanning-tree port priority (configurable on a per-CIST interface basis) 128.
Spanning-tree port cost (configurable on a per-CIST interface basis) 1000 Mbps: 4.
100 Mbps: 100 (for the internal 100 Mbps
management module ports).
100 Mbps: 19 (for the external ports).
10 Mbps: 100.
Hello time 2 seconds.
Forward-delay time 15 seconds.
Maximum-aging time 20 seconds.
Maximum hop count 20 hops.