Chapter 6: Spanning Tree Configuration; Overview: Single, Rapid And Multiple Spanning Tree Protocols - Enterasys Matrix DFE-Gold Series Configuration Manual

This chapter describes the Spanning Tree Configuration set of commands and how to use them.
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Overview: Single, Rapid and Multiple Spanning Tree Protocols

Configuring Spanning Tree Bridge Parameters
Configuring Spanning Tree Port Parameters
Configuring Spanning Tree Loop Protect Features
Overview: Single, Rapid and Multiple Spanning Tree Protocols
The IEEE 802.1D Spanning Tree Protocol (STP) resolves the problems of physical loops in a
network by establishing one primary path between any two devices in a network. Any duplicate
paths are barred from use and become standby or blocked paths until the original path fails, at
which point they can be brought into service.
RSTP
The IEEE 802.1w Rapid Spanning Protocol (RSTP), an evolution of 802.1D, can achieve much
faster convergence than legacy STP in a properly configured network. RSTP significantly reduces
the time to reconfigure the network's active topology when physical topology or configuration
parameter changes occur. It selects one switch as the root of a Spanning Tree‐connected active
topology and assigns port roles to individual ports on the switch, depending on whether that port
is part of the active topology.
RSTP provides rapid connectivity following the failure of a switch, switch port, or a LAN. A new
root port and the designated port on the other side of the bridge transition to forwarding through
an explicit handshake between them. By default, user ports are configured to rapidly transition to
forwarding in RSTP.
MSTP
The IEEE 802.1s Multiple Spanning Tree Protocol (MSTP) builds upon 802.1D and RSTP by
optimizing utilization of redundant links between switches in a network. When redundant links
exist between a pair of switches running single STP, one link is forwarding while the others are
blocking for all traffic flowing between the two switches. The blocking links are effectively used
only if the forwarding link goes down. MSTP assigns each VLAN present on the network to a
particular Spanning Tree instance, allowing each switch port to be in a distinct state for each such
instance: blocking for one Spanning Tree while forwarding for another. Thus, traffic associated
with one set of VLANs can traverse a particular inter‐switch link, while traffic associated with
another set of VLANs can be blocked on that link. If VLANs are assigned to Spanning Trees
wisely, no inter‐switch link will be completely idle, maximizing network utilization.
Spanning Tree Configuration
Enterasys Matrix DFE-Gold Series Configuration Guide 6-1
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