Users Guide

• Revision is a 2-byte number. The default revision number OS is 0.
• VLAN-to-instance mapping is the placement of a VLAN in an MSTI.
For a bridge to be in the same MSTP region as another, all three of these qualities must match exactly. The default values for
the name and revision number must match on all Dell Networking OS devices. If there are non-Dell devices that participate in
MSTP, ensure these values match on all devices.
NOTE: Some non-Dell devices may implement a non-null default region name. SFTOS, for example, uses the Bridge ID,
while others may use a MAC address.
Changing the Region Name or Revision
To change the region name or revision, use the following commands.
• Change the region name.
PROTOCOL MSTP mode
name name
• Change the region revision number.
PROTOCOL MSTP mode
revision number
Example of the name Command
To view the current region name and revision, use the show spanning-tree mst configuration command from EXEC
Privilege mode.
Dell(conf-mstp)#name my-mstp-region
Dell(conf-mstp)#exit
Dell(conf)#do show spanning-tree mst config
MST region name: my-mstp-region
Revision: 0
MSTI VID
1 100
2 200-300
Modifying Global Parameters
The root bridge sets the values for forward-delay, hello-time, max-age, and max-hops and overwrites the values set on other
MSTP bridges.
• Forward-delay — the amount of time an interface waits in the Listening state and the Learning state before it transitions to
the Forwarding state.
• Hello-time — the time interval in which the bridge sends MSTP bridge protocol data units (BPDUs).
• Max-age — the length of time the bridge maintains configuration information before it refreshes that information by
recomputing the MST topology.
• Max-hops — the maximum number of hops a BPDU can travel before a receiving switch discards it.
NOTE
: Dell Networking recommends that only experienced network administrators change MSTP parameters. Poorly
planned modification of MSTP parameters can negatively affect network performance.
To change the MSTP parameters, use the following commands on the root bridge.
1 Change the forward-delay parameter.
PROTOCOL MSTP mode
forward-delay seconds
The range is from 4 to 30.
Multiple Spanning Tree Protocol (MSTP) 534