Specifications
STP Configurations
ExtremeWare XOS 11.0 Concepts Guide 203
To support hitless failover, the primary MSM replicates STP BPDUs to the backup, which allows the
MSMs to run STP in parallel. Although both MSMs receive STP BPDUs, only the primary transmits STP
BPDUs to neighboring switches and participates in STP.
To initiate hitless failover on a network that utilizes STP:
1 Confirm that the MSMs are synchronized and have identical software and switch configurations
using the
show switch {detail} command. The output displays the status of the MSMs, with the
primary MSM showing
MASTER and the backup MSM showing BACKUP (InSync).
If the MSMs are not synchronized, proceed to step 2.
If the MSMs are synchronized, proceed to step 3.
2 If the MSMs are not synchronized, replicate all saved images and configuration from the primary to
the backup using the
synchronize command.
3 Initiate failover using the run msm-failover command.
For more detailed information about verifying the status of the MSMs and system redundancy, see
“System Redundancy” on page 47.
STP Configurations
When you assign VLANs to an STPD, pay careful attention to the STP configuration and its effect on
the forwarding of VLAN traffic.
This section describes three types of STP configurations:
• Basic STP
• Multiple STPDs on a single port (which uses EMISTP)
• A VLAN that spans multiple STPDs
Basic STP Configuration
This section describes a basic, 802.1D STP configuration. Figure 17 illustrates a network that uses VLAN
tagging for trunk connections. The following four VLANs have been defined:
• Sales is defined on switch A, switch B, and switch M.
• Personnel is defined on switch A, switch B, and switch M.
• Manufacturing is defined on switch Y, switch Z, and switch M
• Engineering is defined on switch Y, switch Z, and switch M.
• Marketing is defined on all switches (switch A, switch B, switch Y, switch Z, and switch M).
Two STPDs are defined:
• STPD1 contains VLANs Sales and Personnel.
• STPD2 contains VLANs Manufacturing and Engineering.
The carrier and protected VLANs are also defined:
• Sales is the carrier VLAN on STPD1.
• Personnel is a protected VLAN on STPD1.