Configuration Example

Virtual LANs

Virtual LANs (VLANs) enable network managers to group users logically rather than by physical location.

With VLANs, switches can support more than one subnet (or VLAN) on each switch, and can give routers and switches the opportunity to support multiple subnets on a single physical link. Layer 3 switching software supports VLAN frame encapsulation through implementation of the Inter-Switch Link (ISL) protocol and the IEEE 802.1Q standard. ISL is a Cisco protocol for interconnecting multiple switches and maintaining VLAN information as traffic travels between switches. The IEEE 802.1Q standard provides a method for secure bridging of data across a shared backbone.

Command	Purpose
Switch# configure terminal Switch(config)#	Enters global configuration mode.
Switch(config)# interface {gigabitethernet fastethernet} card/subcard/port.subinterface Switch(config-subif)#	Enters subinterface configuration mode.
Switch(config-subif)# encapsulation isl vlan-id or Switch(config-subif)# encap dot1q vlan-id native	Specifies ISL encapsulation for the Ethernet frames sent from this subinterface, with a header that maintains the specified VLAN ID between network nodes. or Specifies 802.1Q encapsulation for Ethernet frames sent from the subinterface, with a header that maintains the specified native VLAN ID between network nodes.
Switch(config-subif)# bridge-group bridge-group	Assigns the subinterface a bridge group number.
Switch(config-subif)# interface {gigabitethernet fastethernet} card/subcard/port Switch(config-if)#	Enters interface configuration mode to configure the Ethernet main interface.
Switch(config-if)# bridge-group bridge-group	Assigns the main interface to the bridge group.
Switch(config-if)# exit	Returns to global configuration mode.
Switch(config)# bridge bridge-group protocol ieee	Specifies that the bridge group will use the IEEE Ethernet Spanning Tree Protocol.

5-5

Example

Switch> enable

Switch# configure terminal

Switch(config)# interface gigabitethernet 0/0/1.1

Switch(config-subif)# encapsulation isl 50

Switch(config-subif)# bridge-group 1

Switch(config-subif)# interface gigabitethernet 11/0/0

Switch(config-if)# bridge-group 1

Switch(config-if)# exit

Switch(config)# bridge 1 protocol ieee

Switch(config)# interface fastethernet 10/0/1.2

Switch(config-subif)# encapsulation isl 100

Switch(config-subif)# bridge-group 2

Switch(config-subif)# interface fastethernet 9/0/2

Switch(config-if)# bridge-group 2

Switch(config-if)# exit

Switch(config)# bridge 2 protocol ieee

Switch(config)# exit

Switch# copy system:running-config nvram:startup-config

Verifying

Switch# show vlan 50

Virtual LAN ID: 50 (Inter Switch Link Encapsulation)

vLAN Trunk Interface: GigabitEthernet0/0/1.

Protocols Configured: Address: Received: Transmitted:

Bridging Bridge Group 1 0

Switch# more system:running-config

!

<Information deleted>

!

interface GigabitEthernet0/0/1.1

encapsulation isl 50

no ip redirects

no ip route-cache

bridge-group 1

!

<Information deleted>
      

Ether-Channel

EtherChannel is a logical aggregation of multiple Ethernet interfaces. EtherChannel is designed primarily for host-to-switch connectivity or Inter-Switch Link (ISL) switch-to-switch connectivity.

Configuring a Fast EtherChannel (FEC) or a Gigabit EtherChannel (GEC) consists of the following two-step process:

Step 1: Create an EtherChannel interface (port channel) and assign a network address.

Step 2: Assign the Fast Ethernet or Gigabit Ethernet interfaces (up to four) to the port channel.

When assigning interfaces to a specific port channel, the interfaces must all be Fast Ethernet, Gigabit Ethernet, or Enhanced Gigabit Ethernet. You cannot mix interface types within a single port-channel.

Command	Purpose
Switch> enable	Enters privileged EXEC mode.
Switch# configure terminal Switch(config)#	Enters global configuration mode.
Switch(config)# interface port-channel channel-number Switch(config-if)#	Creates the EtherChannel interface and enters interface configuration mode. The channel number can be from 1 to 64 for FECs and GECs.
Switch(config-if)# ip address ip-address subnet-mask	Assigns an IP address and subnet mask to the EtherChannel interface.
Switch(config-if)# no shutdown	Enables the EtherChannel interface.
Switch(config-if)# exit Switch(config)#	Exits interface configuration mode. Optionally, you can remain in interface configuration mode and enable other supported interface commands to meet your requirements.
Switch(config)# interface {gigabitethernet fastethernet} card/subcard/port Switch(config-if)	Enters interface configuration mode.
Switch(config-if)# no ip address	Disables the IP address. Note If the Fast Ethernet or Gigabit Ethernet interface already exists and has an IP address assigned, you must disable it before performing the next step. The Ethernet interface uses the IP address assigned to the EtherChannel interface.
Switch(config-if)# channel-group channel-number	Assigns the Fast Ethernet or Gigabit Ethernet interfaces to the EtherChannel. The channel number must be the same channel number you assigned to the EtherChannel interface.
Switch(config-if)# exit Switch(config)#	Returns to global configuration mode. Repeat Steps 7 through 9 to add up to four Fast Ethernet or Gigabit Ethernet interfaces to the Fast EtherChannel.
Switch(config)# end Switch#	Returns to privileged EXEC mode.
Switch# copy system:running-config nvram:startup-config	Saves your configuration changes to NVRAM.

Example

Switch> enable

Switch# configure terminal

Switch(config)# interface port-channel 5

Switch(config-if)# ip address 209.165.200.225 255.255.255.224

Switch(config-if)# no shutdown

Switch(config-if)# exit

Switch(config)# interface fastethernet 0/0/0

Switch(config-if)# no ip address

Switch(config-if)# channel-group 5

Switch(config-if)# end

Switch# copy system:running-config nvram:startup-config