Cisco Catalyst 2900 Series XL Especificaciones descargar pdf (Pagina 167)

6-47

Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide

78-6511-06

Chapter 6 Configuring the System

Configuring STP

Configuring STP Root Guard

The Layer 2 network of a service provider (SP) can include many connections to switches that are not

owned by the SP. In such a topology, STP can reconfigure itself and select a customer switch as the STP

root switch, as shown in Figure 6-11. You can avoid this situation by configuring the root-guard feature

on interfaces that connect to switches outside of your customer’s network. If STP calculations cause an

interface in the customer network to be selected as the root port, root guard then places the interface into

the root-inconsistent (blocked) state to prevent the customer switch from becoming the root switch or

being in the path to the root.

If a switch outside the network becomes the root switch, the interface is blocked (root-inconsistent state),

and STP selects a new root switch. The customer switch does not become the root switch and is not in

the path to the root.

Caution Misuse of this feature can cause a loss of connectivity.

Figure 6-11 STP in a Service Provider Network

Root guard enabled on a port applies to all the VLANs that the port belongs to. Each VLAN has its own

instance of STP.

Beginning in privileged EXEC mode, follow these steps to set root guard on a port:

Use the no version of the spanning-tree rootguard command to disable the root guard feature.

Customer network

Potential

STP root without

root guard enabled

Enable the root-guard feature

on these interfaces to prevent

switches in the customer

network from becoming

the root switch or being

in the path to the root.

Desired

root switch

Service-provider network

43578

Command Purpose

Step 1

configure terminal Enter global configuration mode.

Step 2

interface interface Enter interface configuration mode, and enter the port to be configured.

Step 3

spanning-tree rootguard Enable root guard on the port.

Step 4

end Return to privileged EXEC mode.

Step 5

show running-config Verify that the port is configured for root guard.

1 2 ... 162 163 164 165 166 167 168 169 170 171 172 ... 321 322

Comentarios a estos manuales

Sin comentarios

Cisco Catalyst 2900 Series XL Especificaciones Pagina 167

Comentarios a estos manuales

Relacionado con productos y manuales para Software Cisco Catalyst 2900 Series XL