Dell Converged Enhanced Ethernet Administrator’s Guide 4953-1002116-01STP, RSTP, and MSTP configuration guidelines and restrictions 65. Map a VLAN to an MSTP instance using the instance command. For more details see “Mappinga VLAN to an MSTP instance” on page 55.switch(conf-mstp)#instance 1 vlan 2, 3switch(conf-mstp)#instance 2 vlan 4-6switch(conf-mstp)#instance 1 priority 40966. Specify the maximum hops for a BPDU to prevent the messages from looping indefinitely onthe interface using the max-hops hop_count command. For more details see “Specifying themaximum number of hops for a BPDU (MSTP)” on page 56.switch(conf-mstp)#max-hops 257. Enter the copy command to save the running-config file to the startup-config file.switch(conf-mstp)#exitswitch(config)#endswitch#copy running-config startup-configFor more information on MSTP, see “STP, RSTP, and MSTP configuration and management” onpage 51.STP, RSTP, and MSTP configuration guidelines and restrictionsFollow 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 connectedon both sides of parallel links.• LAGs are treated as normal links and by default are enabled for STP.• You can have 16 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-instancemapping 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 isautomatically enabled.• For two or more switches to be in the same MSTP region, they must have the sameVLAN-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 thefront-end Ten Gigabit Ethernet ports that may run FCoE traffic. This may result in lost ordropped FCoE logins.
