Extreme Networks EPICenter 6.0, Reference Manual

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EPICenter Reference Guide
543
C The Spanning Tree Monitor
This chapter describes how to use the EPICenter Spanning Tree Monitor module for:
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Viewing the configuration and status of STP domains
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Viewing the status and configuration of VLANs associated with an STP domain
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Viewing the status and configuration of devices and ports associated with an STP domain
NOTE
In order for the EPICenter server to acquire information about a device’s STPD configuration, that device must be
running ExtremeWare 6.2.2 or later. Prior to version 6.2.2, the ExtremeWare SNMP agent did not provide Spanning
Tree information.
Overview of the Spanning Tree Monitor
The EPICenter Spanning Tree Monitor module displays information about STP domains at the domain,
VLAN, device, and port levels.
STP is a bridge-based mechanism for providing fault tolerance on networks. In the Extreme Networks
implementation of STP, a switch can be partitioned into multiple virtual bridges. Each virtual bridge
can run an independent Spanning Tree instance, called a
Spanning Tree Domain (STPD). Each STP
domain has its own root bridge and active path. After an STPD is created, one or more VLANs can be
assigned to it, depending on the mode of the ports.
The default switch configuration includes a single STP domain called s0 . The default VLAN is a
member of STPD s0.
STP ports can run in one of three modes:
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802.1D mode. which conforms to the IEEE 802.1D standard.
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Extreme Multiple Instance Spanning Tree Protocol (EMISTP) mode, an Extreme implementation of
STP that allows a port to belong to multiple STP domains. This is the default on Extreme switches.
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Enhanced Per-VLAN Spanning Tree Protocol (PVST+) mode, an STP implementation widely
deployed on many vendors’ switches, that is interoperable with 802.1Q spanning tree.
A physical port can belong to multiple STPDs through membership in multiple VLANs, if the port is in
EMISTP mode. In addition, a single VLAN can span multiple STPDs.
STP configuration must be done through the EPICenter Telnet applet or through the ExtremeWare
command line interface. The STP monitor displays summary and detailed STP configuration
information about the devices being managed by the EPICenter server. It allows you to view STP
configuration information network-wide rather than only device by device as is the case through the
ExtremeWare CLI.
The EPICenter server receives STP topology information through traps from the SNMP agent in the
switch, and through polling. Not all STP-related changes generate traps—for example, updating the
root port and path cost for the previous root when the root changes. The EPICenter server relies on