Cisco Systems OL-4580-01 manual Configuring Port Fast on an Interface, 1-16

Chapter 1 Configuring Interfaces and Circuits

Configuring Interfaces

Configuring Spanning-Tree Bridge State

By default, an Ethernet interface is set to the enabled bridge state Use the bridge state command to set the spanning-tree bridge state for an Ethernet interface or for a trunked Ethernet interface. .

For example, to enable the bridge state for e7 on the CSS 11501, enter:

(config-if[e7])#bridge state enable

For example, to enable the bridge state for the I/O module in slot 1, Ethernet port 1, in VLAN3, enter:

(config-if-vlan[1/1-3])# bridge state enable

To disable the bridge state, enter:

(config-if-vlan[1/1-3])# bridge state disable

Configuring Port Fast on an Interface

The Port Fast feature immediately brings a CSS Ethernet interface (port) to the Spanning Tree Protocol (STP) forwarding state from a blocking state, bypassing the listening and learning states. You can specify Port Fast for ports connected to a single workstation or server to allow those devices to immediately connect to the network, rather than waiting for the STP to converge.

Ports connected to a single workstation or server should not receive bridge protocol data units (BPDUs).

Caution The purpose of Port Fast is to minimize the time ports must wait for STP to converge. This means that the Port Fast function is effective only when used on ports connected to end stations in the network. If you enable Port Fast on a port connecting to another switch, you risk creating a spanning-tree loop. Consider using the BDPU guard feature to avoid creating a spanning-tree loop.

This section includes the following topics:

•Enabling Port Fast

•Enabling BPDU Guard

•Showing Port Fast Information

	Cisco Content Services Switch Routing and Bridging Configuration Guide
1-16	OL-4580-01