Converged Enhanced Ethernet Administrator’s Guide 63
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STP, RSTP, and MSTP configuration guidelines and restrictions 7
DRAFT: BROCADE CONFIDENTIAL
For more information on MSTP, see “STP, RSTP, and MSTP configuration and management” on
page6 4.
STP, RSTP, and MSTP configuration guidelines and restrictions
Follow these configuration guidelines and restrictions when configuring STP, RSTP, and MSTP:
•You have to disable one form of xSTP before enabling another.
•Packet drops or packet flooding may occur if you do not enable xSTP on all devices connected
on both sides of parallel links.
•LAGs are treated as normal links and by default are enabled for STP.
•You can have 15 MSTP instances and one MSTP region.
•Create VLANs before mapping them to MSTP instances.
•The MSTP force-version option is not supported.
•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.
•When you enable MSTP by using the global protocol spanning-tree mstp command, RSTP is
automatically enabled.
•For two or more switches to be in the same MSTP region, they must have the same
VLAN-to-instance map, the same configuration revision number, and the same name.
•Spanning Tree topologies must not be enabled on any direct server connections to the
front-end Ten Gigabit Ethernet ports that may run FCoE traffic. This may result in lost or
dropped FCoE logins.
Default STP, RSTP, and MSTP configuration
Table 16 lists the default STP, RSTP, and MSTP configuration.
TABLE 16 Default STP, RSTP, and MSTP configuration
Parameter Default setting
Spanning-tree mode By default, STP, RSTP, and MSTP are disabled
Bridge priority 32768
Bridge forward delay 15 seconds
Bridge maximum aging time 20 seconds
Error disable timeout timer Disabled
Error disable timeout interval 300 seconds
Port-channel path cost Standard
Bridge hello time 2 seconds
Flush MAC addresses from the VLAN FDB Enabled