Stp Port Types; Stp Edge Ports; Bridge Assurance - Cisco Nexus 7000 Series Configuration Manual

STP Port Types

functionality may be incorporated into the IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) standard, we
recommend using these extensions. All of these extensions, except PVST Simulation, can be used with both
Rapid PVST+ and MST. You use PVST Simulation only with MST.
The available extensions are spanning tree edge ports (which supply the functionality previously known as
PortFast), Bridge Assurance, BPDU Guard, BPDU Filtering, Loop Guard, Root Guard, and PVT Simulation.
Many of these features can be applied either globally or on specified interfaces.
Note Spanning tree is used to refer to IEEE 802.1w and IEEE 802.1s. If the text is discussing the IEEE 802.1D
Spanning Tree Protocol, 802.1D is stated specifically.
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.
Edge ports, which are connected to Layer 2 hosts, can be either an access port or a trunk port.
Note If you configure a port connected to a Layer 2 switch or bridge as an edge port, you might create a bridging
loop.
Network ports are connected only to Layer 2 switches or bridges.
If you mistakenly configure ports that are connected to Layer 2 hosts, or edge devices, as spanning tree
Note
network ports, those ports will automatically move into the blocking state.

STP Edge Ports

You connect STP edge ports only to Layer 2 hosts. 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 Layer 2 hosts should not receive STP bridge protocol data units (BPDUs).

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 or other software failure
and a device that continues to forward data traffic when it is no longer running the spanning tree algorithm.
Note Bridge Assurance is supported only by Rapid PVST+ and MST.
Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.x
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Configuring STP Extensions Using Cisco NX-OS