Cisco Systems N3KC3064TFAL3, N3KC3048TP1GE manual Configuring STP Extensions, About STP Extensions

C H A P T E R 10

Configuring STP Extensions

This chapter contains the following sections:

•About STP Extensions, page 113

About STP Extensions

Cisco has added extensions to STP that make convergence more efficient. In some cases, even though similar functionality may be incorporated into the IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) standard, we recommend using these extensions. All of these extensions can be used with both RPVST+ and MST.

The available extensions are spanning tree port types, Bridge Assurance, BPDU Guard, BPDU Filtering, Loop Guard, and Root Guard. 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.

Information About STP Extensions

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.

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).

Cisco Nexus 3000 NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)U3(1)

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