Cisco Systems 8540 CSR, 8510 CSR Enters subinterface configuration mode, Routerconfig-subif#

Chapter 4 Configuring Interfaces

Configuring ISL VLAN Encapsulation

Figure 4-2 Example of an ISL VLAN Bridging Configuration

Bridge-group 1

1/0/1.1

	1/0/0	VLAN 50
		encap isl 50
Campus		encap isl 100	Campus
switch			switch
router			router

VLAN 100

3/0/1 1/0/1.2 Bridge-group 2

17489

To configure the Layer 3 VLANs shown in Figure 4-2,perform the following steps, beginning in global

	configuration mode:
	Command	Purpose
Step 1
	Router(config)# interface fastethernet	Enters subinterface configuration mode.
	slot/subslot/interface.subinterface
	Router(config-subif)#
Step 2
	Router(config-subif)# encapsulation isl vlan-id	Specifies ISL encapsulation for the Ethernet
		frames sent from this subinterface with a
		header that maintains the specified VLAN ID
		between network nodes.
Step 3
	Router(config-subif)# bridge-groupbridge-group	Assigns the subinterface a bridge group
		number.
		Note	When you are configuring VLAN
			routing, skip this step.
Step 4
	Router(config-subif)# interface fastethernet	Enters interface configuration mode to
	slot/subslot/interface	configure the Fast Ethernet main interface.
	Router(config-if)#
Step 5
	Router(config-if)# bridge-groupbridge-group	Assigns the main interface to the bridge
		group.
Step 6
	Router(config-if)# exit	Returns to global configuration mode.
	Router(config)#
Step 7
	Router(config)# bridge bridge-groupprotocol ieee	Specifies that the bridge group will use the
		IEEE Ethernet Spanning Tree Protocol.

	Layer 3 Switching Software Feature and Configuration Guide
78-6235-04, Cisco IOS Release 12.0(10)W5(18)		4-9