Default Mstp Configuration - Cisco Catalyst 3550 series Software Configuration Manual

Configuring MSTP Features

Default MSTP Configuration

Table 17-3
Table 17-3 Default MSTP Configuration
Feature
Spanning-tree mode
Switch priority (configurable on a per-CIST interface basis)
Spanning-tree port priority (configurable on a per-CIST interface basis)
Spanning-tree port cost (configurable on a per-CIST interface basis)
Hello time
Forward-delay time
Maximum-aging time
Maximum hop count
For information about the supported number of spanning-tree instances, see the
Spanning-Tree Instances" section on page
MSTP Configuration Guidelines
These are the configuration guidelines for MSTP:
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Catalyst 3550 Multilayer Switch Software Configuration Guide
17-12
shows the default MSTP configuration.
When you enable MST by using the spanning-tree mode mst global configuration command, RSTP
is automatically enabled. Per-VLAN RSTP is not supported in software releases earlier than Cisco
IOS Release 12.1(13)EA1.
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.
The UplinkFast, BackboneFast, and cross-stack UplinkFast features are not supported with the
MSTP.
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 VLANs run MSTP.) For more
information, see the "Spanning-Tree Interoperability and Backward Compatibility" section on
page 16-10. For information on the recommended trunk port configuration, see
Other Features" section on page
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 mapping) 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, all VLAN-to-instance mapping
assignments must match; otherwise, all traffic flows on a single link.
Default Setting
PVST+ (Rapid PVST+ and MSTP are disabled).
32768.
128.
1000 Mbps: 4.
100 Mbps: 19.
10 Mbps: 100.
2 seconds.
15 seconds.
20 seconds.
20 hops.
16-9.
12-19.
Chapter 17 Configuring MSTP
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