Leaflet

OL-11615-01

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_8_5/cmd_ref/set_v.htm#wp1058935

For more information on the set vlan command for the Catalyst 4500, refer to the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/8_3/command/set_s_z.htm#wp1052100

By default, in Cisco IOS all interfaces are disabled on Catalyst 6500 Series switches, and enabled on

Catalyst 4500 Series switches. A previously enabled interface can be disabled using the shutdown

interface command:

Switch(config)# interface

type slot/port

Switch(config-if)# shutdown

This example shows how to disable an interface using the shutdown interface command:

Switch(config)# interface GigabitEthernet2/1

Switch(config-if)# shutdown

Switch(config-if)# end

For more information on the shutdown command, refer to the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/finter

_r/irfshoip.htm#wp1018004

In Cisco IOS, by default, all ports are configured as routed interfaces, and because they are not Layer 2

ports they are not associated to a default VLAN. However, as soon as a port is configured as a Layer 2

switched interface using the switchport command, the port is automatically set to default VLAN 1. To

change the default VLAN, use the switchport access vlan command:

Switch(config-if)# switchport access vlan

vlan_ID

This example shows how the unused port is set to unused VLAN 560:

Switch(config)# interface GigabitEthernet2/1

Switch(config-if)# switchport access vlan 560

Switch(config-if)#

For more information on the switchport access vlan command, refer to the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/122sx/cmdref/s1.htm#wp1088860

Note Catalyst 6500 and 4500 Series switches provide other security services that are not directly related to

infrastructure protection, but that help secure the network. Refer to

Other Security Services, page 109 to

learn more about these security services.

Spanning Tree Protocol Security

As defined in the IEEE 802.1D standard, the Spanning Tree Protocol (STP) is a link management

protocol for bridged networks that provides path redundancy while preventing undesirable loops in

networks built of multiple active paths. Loops occur when multiple active paths exist between hosts, and

which could result in an endless loop of traffic in the LAN that could bring the network down. STP

implements an algorithm that guarantees a loop-free topology. With STP, all switches and bridges in the

LAN exchange BPDU messages containing topology information. The STP algorithm uses the topology

information to build a topological tree where only one active path at a time exists between any two hosts.

Redundant paths are shut down and used as backups in case the primary paths fail. Changes to the

physical topology normally trigger a recalculation of the topological tree.