Configuring Multiple Spanning Tree - Cisco nexus 5000 series Configuration Manual

Configuring Multiple Spanning Tree

This chapter contains the following sections:
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Information About MST
MST Overview
Spanning tree is used to refer to IEEE 802.1w and IEEE 802.1s. If the text is discussing the IEEE 802.1D
Note
Spanning Tree Protocol, 802.1D is stated specifically.
MST maps multiple VLANs into a spanning tree instance with each instance having a spanning tree topology
independent of other spanning tree instances. This architecture provides multiple forwarding paths for data
traffic, enables load balancing, and reduces the number of STP instances required to support a large number
of VLANs.
MST provides rapid convergence through explicit handshaking as each MST instance uses the IEEE 802.1w
standard, which eliminates the 802.1D forwarding delay and quickly transitions root bridge ports and designated
ports to the forwarding state.
MAC address reduction is always enabled while you are using MST. You cannot disable this feature.
MST improves spanning tree operation and maintains backward compatibility with these STP versions:
• Original 802.1D spanning tree
• Rapid per-VLAN spanning tree (Rapid PVST+)
• IEEE 802.1s defined MST and was incorporated into IEEE 802.1Q.
OL-25842-01
Information About MST, page 187
Configuring MST, page 195
Verifying the MST Configuration, page 213
IEEE 802.1w defined the Rapid Spanning Tree Protocol (RSTP) and was incorporated into IEEE 802.1D.
Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.1(3)N1(1)
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