Configuring Stp Extensions; Understanding Stp Port Types; Understanding Bridge Assurance - Cisco nexus 5000 series Cli Configuration Manual

Information About STP Extensions
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Understanding STP Port Types

You can configure a spanning tree port as an edge port, a network port, or a normal port. A port can be
in only one of these states at a given time. The default spanning tree port type is normal. Depending on
the type of device to which the interface is connected, you can configure a spanning tree port as one of
these port types.
This section includes the following topics:
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Spanning Tree Edge Ports
Edge ports, which are connected to hosts, can be either an access port or a trunk port. The edge port
interface immediately transitions to the forwarding state, without moving through the blocking or
learning states. (This immediate transition was previously configured as the Cisco-proprietary feature
PortFast.)
Interfaces that are connected to hosts should not receive STP Bridge Protocol Data Units (BPDUs).
If you configure a port connected to another switch set as an edge port, you might create a bridging loop.
Note
Spanning Tree Network Ports
Network ports are connected only to switches or bridges. Bridge Assurance is enabled only on network
ports.
If you mistakenly configure ports that are connected to hosts or other edge devices, as spanning tree
Note
network ports, those ports will automatically move into the blocking state.
Spanning Tree Normal Ports
Normal ports can be connected to either hosts, switches, or bridges. These ports function as normal
spanning tree ports.
The default spanning tree interface is normal ports.

Understanding Bridge Assurance

You can use Bridge Assurance to protect against certain problems that can cause bridging loops in the
network. Specifically, you use Bridge Assurance to protect against a unidirectional link failure and a
device that continues to forward data traffic when it is no longer running the spanning tree algorithm.
Bridge Assurance is supported only by Rapid PVST+ and MST. Legacy 802.1D spanning tree does not
Note
support Bridge Assurance.
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
1-2
Spanning Tree Edge Ports, page 1-2
Spanning Tree Network Ports, page 1-2
Spanning Tree Normal Ports, page 1-2
Chapter 1

Configuring STP Extensions

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