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Configuring InterVLAN Routing

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Configuring InterVLAN Routing

Understanding How InterVLAN Routing Works

Configuring VTP and VLANs on the Switch

Basic Router Configuration Tasks

Accessing Configuration Mode on the Router

Viewing and Saving the Router Configuration

Bringing Up a Router Interface

Configuring InterVLAN Routing on the RSM

RSM Configuration Guidelines

Accessing the RSM from the Switch

Configuring IP InterVLAN Routing on the RSM

Configuring IPX InterVLAN Routing on the RSM

Configuring AppleTalk InterVLAN Routing on the RSM

Configuring InterVLAN Routing on the RSFC

RSFC Configuration Guidelines

Accessing the RSFC from the Switch

Configuring IP InterVLAN Routing on the RSFC

Configuring IPX InterVLAN Routing on the RSFC

Configuring AppleTalk InterVLAN Routing on the RSFC

Configuring InterVLAN Routing on an External Cisco Router

Configuring IP InterVLAN Routing on an External Router

Configuring IPX InterVLAN Routing on an External Router

Configuring AppleTalk InterVLAN Routing on an External Router

Configuring InterVLAN Routing on the Catalyst 8510 CSR

Creating and Grouping Ports to a Port-Channel Interface

Configuring Subinterfaces for IP InterVLAN Routing

Configuring Redundancy Using HSRP

InterVLAN Routing Configuration Examples

InterVLAN Routing with the RSM Example

Switch A Configuration

Switch B Configuration

Switch C Configuration

RSM Configuration

InterVLAN Routing with the RSFC Example

Example Network Topology

Catalyst 5509 Configuration

Catalyst 5505 Configuration

RSFC Configuration

Redundant RSFCs Using HSRP Example

Example Network Topology

RSFC A Configuration

RSFC B Configuration

InterVLAN Routing with an External Cisco 7505 Router Example

Switch Configuration

Cisco 7505 Configuration

InterVLAN Routing with an External Catalyst 8510 CSR Example

Catalyst 8510 CSR Configuration

Switch A Configuration

Switch B Configuration


Configuring InterVLAN Routing

This chapter describes how to configure switches and routers for inter-virtual LAN (VLAN) routing. The configuration procedures and examples in this chapter are designed as a starting point to help you configure interVLAN routing for your network environment.

Note   For complete syntax and usage information for the IOS commands used in this chapter, refer to the software documentation for your IOS release. For complete syntax and usage information for the switch commands used in this chapter, refer to the Command Reference for your switch software release.

These sections describe how to configure interVLAN routing:

•Understanding How InterVLAN Routing Works

•Configuring VTP and VLANs on the Switch

•Basic Router Configuration Tasks

•Configuring InterVLAN Routing on the RSM

•Configuring InterVLAN Routing on the RSFC

•Configuring InterVLAN Routing on an External Cisco Router

•Configuring InterVLAN Routing on the Catalyst 8510 CSR

•Configuring Redundancy Using HSRP

•InterVLAN Routing Configuration Examples

Understanding How InterVLAN Routing Works

Network devices in different VLANs cannot communicate with one another without a router to route traffic between the VLANs. In most network environments, VLANs are associated with individual networks or subnetworks.

For example, in an IP network, each subnetwork is mapped to an individual VLAN. In a Novell IPX network, each VLAN is mapped to an IPX network number. In an AppleTalk network, each VLAN is associated with a cable range and AppleTalk zone name.

Configuring VLANs helps control the size of the broadcast domain and keeps local traffic local. However, when an end station in one VLAN needs to communicate with an end station in another VLAN, interVLAN communication is required. This communication is supported by interVLAN routing. You configure one or more routers to route traffic to the appropriate destination VLAN.

shows a basic interVLAN routing topology. Switch A is in VLAN 10 and Switch B is in VLAN 20. The router has an interface in each VLAN.

Figure 3-1 Basic InterVLAN Routing Topology

When Host A in VLAN 10 needs to communicate with Host B in VLAN 10, it sends a packet addressed to that host. Switch A forwards the packet directly to Host B, without sending it to the router.

When Host A sends a packet to Host C in VLAN 20, Switch A forwards the packet to the router, which receives the traffic on the VLAN 10 interface. The router checks the routing table, determines the correct outgoing interface, and forwards the packet out the VLAN 20 interface to Switch B. Switch B receives the packet and forwards it to Host C.

shows another common scenario, interVLAN routing over a single trunk connection to the router. The switch has ports in multiple VLANs. InterVLAN routing is performed by a Cisco 7505 router connected to the switch through a full-duplex Fast Ethernet trunk link.

Figure 3-2 InterVLAN Routing Over a Single Trunk Link

Multiple subinterfaces are configured on the physical Fast Ethernet router interface, one for each VLAN supported on the trunk. IntraVLAN traffic (traffic with the source and destination host in the same VLAN) is handled entirely by the switch.

InterVLAN traffic is sent across the trunk to the router. The router checks the routing table, determines the outgoing subinterface (destination VLAN), and sends the traffic back over the trunk to the switch, where it is forwarded out the appropriate switch port.

Configuring VTP and VLANs on the Switch

To successfully configure a router for interVLAN routing, you must configure VTP and create and configure VLANs on the switch.

Note   This section describes the basics of VTP and VLAN configuration. For detailed information on configuring VTP and VLANs, see the Software Configuration Guide for your switch.

To configure VTP and VLANs on the switch, perform this task in privileged mode:

Task
Command

Step 1 Specify the VTP mode.

set vtp mode {client | server | transparent}

Step 2 Configure a VTP domain (if you configured the switch as a VTP client or server).

set vtp domain name

Step 3 Create VLANs on the switch.

set vlan vlan_num

Step 4 Assign ports to the VLAN.

set vlan vlan_num mod_num/port_num


This example shows how to configure VTP, create two VLANs, and assign switch ports to those VLANs: 

Console> (enable) set vtp mode server

VTP domain modified

Console> (enable) set vtp domain Corp_Net

VTP domain Corp_Net modified

Console> (enable) set vlan 100

Vlan 100 configuration successful

Console> (enable) set vlan 200

Vlan 200 configuration successful

Console> (enable) set vlan 100 3/1-12

VLAN 100 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

100   1/1-2

      3/1-12

Console> (enable) set vlan 200 3/13-24

VLAN 200 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

200   1/1-2

      3/13-24

Console> (enable)

Basic Router Configuration Tasks

These sections describe basic router configuration tasks you need to understand before you configure interVLAN routing:

•Accessing Configuration Mode on the Router

•Viewing and Saving the Router Configuration

•Bringing Up a Router Interface

Accessing Configuration Mode on the Router

To access configuration mode on the router, perform this task, beginning in normal EXEC mode:

Task
Command

Step 1 At the EXEC prompt, enter enable mode.

enable

Step 2 At the privileged EXEC prompt, enter global configuration mode.

configure terminal

Step 3 Enter the commands to configure interVLAN routing.

(Refer to the appropriate configuration tasks later in this chapter.)

Step 4 Exit configuration mode.

Ctrl-Z


Viewing and Saving the Router Configuration

To view and save the configuration after you make changes, perform this task in privileged EXEC mode:

Task
Command

Step 1 View the current operating configuration at the privileged EXEC prompt.

show running-config

Step 2 View the configuration in NVRAM.

show startup-config

Step 3 Save the current configuration to NVRAM.

copy running-config startup-config


Bringing Up a Router Interface

In some cases, a router interface might be administratively shut down. You can check the status of an interface using the show interface command.

To bring up a router interface that is administratively shut down, perform this task beginning in global configuration mode:

Task
Command

Step 1 Specify the interface to bring up.

interface interface_type interface_number

Step 2 Bring the interface up.

no shutdown

Step 3 Exit configuration mode.

Ctrl-Z


Configuring InterVLAN Routing on the RSM

Note   This section is for those who are familiar with Cisco IOS software and have some experience configuring Cisco routers. If you are not familiar with configuring Cisco routers, refer to the documentation for your router platform.

These sections describe how to configure interVLAN routing on the Catalyst 5000 family RSM:

•RSM Configuration Guidelines

•Accessing the RSM from the Switch

•Configuring IP InterVLAN Routing on the RSM

•Configuring IPX InterVLAN Routing on the RSM

•Configuring AppleTalk InterVLAN Routing on the RSM

Note   For a detailed configuration example of IP interVLAN routing, see the "InterVLAN Routing with the RSM Example" section.

RSM Configuration Guidelines

Configuring interVLAN routing on the RSM consists of two main procedures:

1 You must create and configure VLANs on the switch and assign VLAN membership to switch ports. For more information, see the "Configuring VTP and VLANs on the Switch" section.

2 You must create and configure VLAN interfaces for interVLAN routing on the RSM. You must configure a VLAN interface for each VLAN between which you want to route traffic.

VLAN interfaces on the RSM are virtual interfaces. However, you configure them much as you do a physical router interface. If you have the optional VIP2 module, you can route traffic between VLAN interfaces and physical interfaces on port adapters installed in the VIP2.

Accessing the RSM from the Switch

You can use the session mod_num command (where mod_num is the slot in which the RSM is installed) to access the RSM from the switch CLI, eliminating the need to connect a terminal directly to the RSM console port. To exit from the router CLI back to the switch CLI, enter exit at the Router> prompt.

This example shows how to access the RSM from the switch CLI, and how to exit the router CLI and return to the switch CLI: 

Console> (enable) session 5

Trying Router-5...

Connected to Router-5.

Escape character is '^]'.


User Access Verification

Password:

Router>exit

Console> (enable)

Configuring IP InterVLAN Routing on the RSM

To configure interVLAN routing for IP, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IP routing on the router1 .

ip routing

Step 2 (Optional) Specify an IP routing protocol2 .

router ip_routing_protocol

Step 3 Specify a VLAN interface on the RSM.

interface vlan-id

Step 4 Assign an IP address to the VLAN.

ip address n.n.n.n mask

Step 5 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IP routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.


This example shows how to enable IP routing on the RSM, create a VLAN interface, and assign the interface an IP address: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ip routing

Router(config)#router rip

Router(config-router)#network 10.0.0.0

Router(config-router)#interface vlan 100

Router(config-if)#ip address 10.1.1.1 255.0.0.0

Router(config-if)#^Z

Router#

Configuring IPX InterVLAN Routing on the RSM

To configure interVLAN routing for Internetwork Packet Exchange (IPX), perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IPX routing on the router1 .

ipx routing

Step 2 (Optional) Specify an IPX routing protocol2 .

ipx router ipx_routing_protocol

Step 3 Specify a VLAN interface on the RSM.

interface vlan-id

Step 4 Assign a network number to the VLAN3 .

ipx network [network | unnumbered] encapsulation encapsulation-type

Step 5 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IPX routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.

3 This enables IPX routing on the VLAN. When you enable IPX routing on the VLAN, you can also specify an encapsulation type.


This example shows how to enable IPX routing on the RSM, create a VLAN interface, and assign the interface an IPX network address: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ipx routing

Router(config)#ipx router rip

Router(config-ipx-router)#network all

Router(config-ipx-router)#interface vlan100

Router(config-if)#ipx network 100 encapsulation snap        

Router(config-if)#^Z

Router#

Configuring AppleTalk InterVLAN Routing on the RSM

To configure interVLAN routing for AppleTalk, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable AppleTalk routing on the router1 .

appletalk routing

Step 2 Specify a VLAN interface on the RSM.

interface vlan-id

Step 3 Assign a cable range to the VLAN.

appletalk cable-range cable-range

Step 4 Assign a zone name to the VLAN.

appletalk zone zone-name

Step 5 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.


This example shows how to enable AppleTalk routing on the RSM, create a VLAN interface, and assign the interface an AppleTalk cable-range and zone name: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#appletalk routing

Router(config)#interface vlan100

Router(config-if)#appletalk cable-range 100-100

Router(config-if)#appletalk zone Engineering

Router(config-if)#^Z

Router#

Configuring InterVLAN Routing on the RSFC

Note   This section assumes familiarity with Cisco IOS software and Cisco router configuration. If you are not familiar with configuring Cisco routers, refer to the documentation for your router platform.

These sections describe how to configure interVLAN routing on the Catalyst 5000 family RSFC:

•RSFC Configuration Guidelines

•Accessing the RSFC from the Switch

•Configuring IP InterVLAN Routing on the RSFC

•Configuring IPX InterVLAN Routing on the RSFC

•Configuring AppleTalk InterVLAN Routing on the RSFC

Note   For a detailed configuration example of IP interVLAN routing on the RSFC, see the "InterVLAN Routing with the RSFC Example" section.

RSFC Configuration Guidelines

Configuring interVLAN routing on the RSFC consists of two main procedures:

1 You must create and configure VLANs on the switch and assign VLAN membership to switch ports. For more information, see the "Configuring VTP and VLANs on the Switch" section.

2 You must create and configure VLAN interfaces for interVLAN routing on the RSFC. You must configure a VLAN interface for each VLAN for which you want to route traffic.

VLAN interfaces on the RSFC are virtual interfaces. However, you configure them in the same way you configure a physical router interface.

Accessing the RSFC from the Switch

You can use the session mod_num command (where mod_num is the slot number associated with the RSFC) to access the RSFC from the switch CLI, eliminating the need to connect a terminal directly to the RSFC console port. To exit from the router CLI back to the switch CLI, enter exit at the RSFC command prompt.

This example shows how to access the RSFC from the switch CLI, and how to exit the router CLI and return to the switch CLI. In this example, because the RSFC is installed on the supervisor engine in slot 1, the RSFC is assigned module number 15. An RSFC installed on the supervisor engine in slot 2 is assigned module number 16. 

Console> (enable) session 15

Trying Router-15...

Connected to Router-15.

Escape character is '^]'.


User Access Verification

Password:

Router>exit

Console> (enable)

Configuring IP InterVLAN Routing on the RSFC

To configure interVLAN routing for IP on the RSFC, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IP routing on the router1 .

ip routing

Step 2 (Optional) Specify an IP routing protocol2 .

router ip_routing_protocol

Step 3 Specify a VLAN interface on the RSFC.

interface vlan-id

Step 4 Assign an IP address to the VLAN interface.

ip address n.n.n.n mask

Step 5 Bring up the interface, if necessary.

no shutdown

Step 6 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IP routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.


This example shows how to enable IP routing on the RSFC, create a VLAN interface, and assign the interface an IP address: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ip routing

Router(config)#router rip

Router(config-router)#network 10.0.0.0

Router(config-router)#interface vlan 100

Router(config-if)#ip address 10.1.1.1 255.0.0.0

Router(config-if)#no shutdown

Router(config-if)#^Z

Router#

Configuring IPX InterVLAN Routing on the RSFC

To configure interVLAN routing for Internetwork Packet Exchange (IPX) on the RSFC, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IPX routing on the router1 .

ipx routing

Step 2 (Optional) Specify an IPX routing protocol2 .

ipx router ipx_routing_protocol

Step 3 Specify a VLAN interface on the RSFC.

interface vlan-id

Step 4 Assign a network number to the VLAN interface3 .

ipx network [network | unnumbered] encapsulation encapsulation-type

Step 5 Bring up the interface, if necessary.

no shutdown

Step 6 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IPX routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.

3 This enables IPX routing on the VLAN. When you enable IPX routing on the VLAN, you can also specify an encapsulation type.


This example shows how to enable IPX routing on the RSFC, create a VLAN interface, and assign the interface an IPX network address: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ipx routing

Router(config)#ipx router rip

Router(config-ipx-router)#network all

Router(config-ipx-router)#interface vlan100

Router(config-if)#ipx network 100 encapsulation snap

Router(config-if)#no shutdown

Router(config-if)#^Z

Router#

Configuring AppleTalk InterVLAN Routing on the RSFC

To configure interVLAN routing for AppleTalk on the RSFC, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable AppleTalk routing on the router1 .

appletalk routing

Step 2 Specify a VLAN interface on the RSFC.

interface vlan-id

Step 3 Assign a cable range to the VLAN interface.

appletalk cable-range cable-range

Step 4 Assign a zone name to the VLAN interface.

appletalk zone zone-name

Step 5 Bring up the interface, if necessary.

no shutdown

Step 6 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.


This example shows how to enable AppleTalk routing on the RSFC, create a VLAN interface, and assign the interface an AppleTalk cable-range and zone name: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#appletalk routing

Router(config)#interface vlan100

Router(config-if)#appletalk cable-range 100-100

Router(config-if)#appletalk zone Engineering

Router(config-if)#no shutdown

Router(config-if)#^Z

Router#

Configuring InterVLAN Routing on an External Cisco Router

Note   This section is for those who are familiar with Cisco IOS software and have some experience configuring Cisco routers. If you are not familiar with configuring Cisco routers, refer to the Cisco IOS Configuration Guides and Command References.

To configure interVLAN routing on an external Cisco router, access the router CLI through the console port or a Telnet connection.

These sections describe how to configure interVLAN routing on an external Cisco router:

•Configuring IP InterVLAN Routing on an External Router

•Configuring IPX InterVLAN Routing on an External Router

•Configuring AppleTalk InterVLAN Routing on an External Router

Note   For a detailed configuration example of IP interVLAN routing with an external Cisco router, see the "InterVLAN Routing with an External Cisco 7505 Router Example" section.

Configuring IP InterVLAN Routing on an External Router

To configure interVLAN routing for IP, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IP routing on the router1 .

ip routing

Step 2 (Optional) Specify an IP routing protocol2 .

router ip_routing_protocol

Step 3 Create a subinterface on a physical interface.

interface interface_type interface_number.subinterface_number

Step 4 Specify the encapsulation and VLAN number to use on the subinterface.

encapsulation encapsulation_type vlan_id

Step 5 Assign an IP address to the subinterface.

ip address n.n.n.n mask

Step 6 Repeat Steps 3-5 for each VLAN between which you want to route traffic.

 

Step 7 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IP routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.


This example shows how to enable IP routing on the router, create two subinterfaces, and specify the encapsulation, VLAN number, and IP address for each subinterface: 

Cisco7505#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Cisco7505(config)#ip routing

Cisco7505(config)#router rip

Cisco7505(config-router)#network 10.0.0.0

Cisco7505(config-router)#interface fastethernet2/0.100

Cisco7505(config-subif)#encapsulation isl 100

Cisco7505(config-subif)#ip address 10.10.1.1 255.255.0.0

Cisco7505(config-router)#interface fastethernet2/0.200

Cisco7505(config-subif)#encapsulation isl 200

Cisco7505(config-subif)#ip address 10.20.1.1 255.255.0.0

Cisco7505(config-subif)#^Z

Cisco7505#

Configuring IPX InterVLAN Routing on an External Router

To configure interVLAN routing for IPX, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IPX routing on the router1 .

ipx routing

Step 2 (Optional) Specify an IPX routing protocol2 .

ipx router ipx_routing_protocol

Step 3 Create a subinterface on a physical interface.

interface interface_type interface_number.subinterface_number

Step 4 Specify the encapsulation and VLAN number to use on the subinterface.

encapsulation encapsulation_type vlan_id

Step 5 Assign a network number to the VLAN3 .

ipx network [network | unnumbered] encapsulation encapsulation-type

Step 6 Repeat Steps 3-5 for each VLAN between which you want to route traffic.

 

Step 7 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IPX routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.

3 This enables IPX routing on the VLAN. When you enable IPX routing on the subinterface, you can also specify an encapsulation type.


This example shows how to enable IPX routing on the router, create two subinterfaces, and specify the encapsulation, VLAN number, and IPX network address for each subinterface: 

Cisco7505#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Cisco7505(config)#ipx routing

Cisco7505(config)#ipx router rip

Cisco7505(config-ipx-router)#network all

Cisco7505(config-ipx-router)#interface fastethernet2/0.100

Cisco7505(config-subif)#encapsulation isl 100

Cisco7505(config-subif)#ipx network 100 encapsulation snap

Cisco7505(config-subif)#interface fastethernet2/0.200

Cisco7505(config-subif)#encapsulation isl 200

Cisco7505(config-subif)#ipx network 200 encapsulation snap

Cisco7505(config-subif)#^Z

Cisco7505#

Configuring AppleTalk InterVLAN Routing on an External Router

To configure interVLAN routing for AppleTalk, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable AppleTalk routing on the router1 .

appletalk routing

Step 2 Create a subinterface on a physical interface.

interface interface_type interface_number.subinterface_number

Step 3 Specify the encapsulation and VLAN number to use on the subinterface.

encapsulation encapsulation_type vlan_id

Step 4 Assign a cable range to the VLAN.

appletalk cable-range cable-range

Step 5 Assign a zone name to the VLAN.

appletalk zone zone-name

Step 6 Repeat Steps 2-5 for each VLAN between which you want to route traffic.

 

Step 7 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.


Configuring InterVLAN Routing on the Catalyst 8510 CSR

Note   This section does not describe a full configuration for the Catalyst 8510 campus switch router (CSR) switch-route processor (SRP). In many cases, you must configure additional interfaces, routing protocols, and other features on the switch before it is fully functional. For complete information on configuring the Catalyst 8510 CSR, refer to the documentation provided with your router.

To configure interVLAN routing on the Catalyst 8510 CSR, access the Catalyst 8510 CSR CLI through the console port or a Telnet connection.

These sections describe how to configure interVLAN routing on the Catalyst 8510 CSR:

•(Optional) Creating and Grouping Ports to a Port-Channel Interface

•Configuring Subinterfaces for IP InterVLAN Routing

Note   For a detailed configuration example of IP interVLAN routing using the Catalyst 8510 CSR, see the "InterVLAN Routing with an External Catalyst 8510 CSR Example" section.

Creating and Grouping Ports to a Port-Channel Interface

A port-channel interface is a logical interface into which you group physical interfaces to form a single logical link.

Note   Configure a port-channel interface on the Catalyst 8510 CSR only if you plan to connect to a switch through a Fast or Gigabit EtherChannel port bundle.

If you plan to use an EtherChannel port bundle to connect the devices, you must configure a port-channel interface, group physical interfaces to the port-channel interface, and configure subinterfaces on the port-channel interface, one for each VLAN for which you want to route traffic.

To create a port-channel interface and group physical interfaces to it, perform this task beginning in global configuration mode:

Task
Command

Step 1 Create a port-channel interface.

interface port-channel interface_number

Step 2 Enter interface configuration mode for each physical interface you want to group to the port-channel interface.

interface interface_type slot/0/interface

Step 3 Associate the interface with the port-channel interface you created.

channel-group port_channel_interface_number

Step 4 Exit configuration mode.

Ctrl-Z


This example shows how to create a port-channel interface on the Catalyst 8510 CSR and how to group interfaces to the port-channel interface: 

Switch>enable

Switch#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#interface port-channel 1

Switch(config-if)#interface fastethernet0/0/0

Switch(config-if)#channel-group 1


FastEthernet0/0/0 added as member-0 to port-channel1

Switch(config-if)#interface fastethernet0/0/1 

Switch(config-if)#channel-group 1


FastEthernet0/0/1 added as member-1 to port-channel1

Switch(config-if)#^Z

Switch#

Configuring Subinterfaces for IP InterVLAN Routing

InterVLAN routing is achieved by configuring subinterfaces on a physical or virtual interface. If the connection to the Layer 2 switch is through a single interface, configure the subinterfaces on the physical interface. If the connection to the Layer 2 switch is through a port-channel interface, configure the subinterfaces on the port-channel interface.

Note   For more information about configuring port-channel interfaces, see "Creating and Grouping Ports to a Port-Channel Interface" section.

Configure one subinterface for each VLAN between which you want to route traffic.

To configure interVLAN routing on a Catalyst 8510 CSR interface, perform this task beginning in global configuration mode:

Task
Command

Step 1 (Optional) Enable IP routing1 .

ip routing

Step 2 (Optional) Specify an IP routing protocol2 .

router ip_routing_protocol

Step 3 Create a subinterface on a physical or port-channel interface.

interface interface_type interface.subinterface

Step 4 Specify the interface encapsulation and VLAN number on the subinterface (this VLAN typically exists already on the connected Layer 2 switch).

encapsulation encapsulation vlan_id

Step 5 Assign an IP address and subnet mask to the subinterface.

ip address ip_addr subnet_mask

Step 6 Repeat Steps 2-4 to create and configure additional subinterfaces on the physical or port-channel interface. Configure one subinterface for each VLAN for which you want to route traffic.

 

Step 7 Exit configuration mode.

Ctrl-Z

1 This step is necessary if you have multiple routers in the network.

2 This step is necessary if you enabled IP routing in Step 1. This step might include other commands, such as specifying the networks to route for using the network router configuration command. Refer to the documentation for your router platform for detailed information on configuring routing protocols.


This example shows how to create three subinterfaces on a port-channel interface and configure them for interVLAN routing (VLANs 1, 2, and 3): 

Switch#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#interface port-channel 1.1 

Switch(config-subif)#encapsulation isl 1

Switch(config-subif)#ip address 172.20.50.33 255.255.255.224

Switch(config-subif)#interface port-channel 1.2

Switch(config-subif)#encapsulation isl 2

Switch(config-subif)#ip address 172.20.50.65 255.255.255.224

Switch(config-subif)#interface port-channel 1.3

Switch(config-subif)#encapsulation isl 3

Switch(config-subif)#ip address 172.20.50.97 255.255.255.224

Switch(config-subif)#^Z

Switch#

Configuring Redundancy Using HSRP

You can configure one or more hot standby router protocol (HSRP) groups on physical router interfaces or RSM/RSFC VLAN interfaces to provide transparent routing backup for the network. Each interface in an HSRP group shares a virtual IP address and MAC address. You can configure end stations and other devices to use the HSRP address as the default gateway so that the failure of one router interface does not interrupt service to those devices.

The interface with the highest HSRP priority is the active interface for that HSRP group.

To configure HSRP on router interfaces, perform this task in interface configuration mode:

Task
Command

Step 1 Enable HSRP and specify the HSRP IP address. If you do not specify a group-number, group 0 is used.

standby [group-number] ip [ip-address]

Step 2 Specify the priority for the HSRP interface. Increase the priority of at least one interface in the HSRP group to a value greater than the default (the default is 100). The interface with the highest priority becomes active for that HSRP group.

standby [group-number] priority priority

Step 3 (Optional) Configure the interface to preempt the current active HSRP interface and become active if the interface priority is higher than the priority of the current active interface.

standby [group-number] preempt [delay delay]

Step 4 (Optional) Set the HSRP Hello timer and holdtime timer for the interface. The default values are 3 (Hello) and 10 (holdtime). All interfaces in the HSRP group should use the same timer values.

standby [group-number] timers hellotime holdtime

Step 5 (Optional) Specify a clear-text HSRP authentication string for the interface. All interfaces in the HSRP group should use the same authentication string.

standby [group-number] authentication string


This example shows how to configure an RSM or RSFC VLAN interface as part of HSRP group 100: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#interface vlan100

Router(config-if)#standby 100 ip 172.20.100.10

Router(config-if)#standby 100 priority 110

Router(config-if)#standby 100 preempt

Router(config-if)#standby 100 timers 5 15

Router(config-if)#standby 100 authentication Secret

Router(config-if)#^Z

Router#

InterVLAN Routing Configuration Examples

These sections contain interVLAN routing configuration examples:

•InterVLAN Routing with the RSM Example

•InterVLAN Routing with the RSFC Example

•Redundant RSFCs Using HSRP Example

•InterVLAN Routing with an External Cisco 7505 Router Example

•InterVLAN Routing with an External Catalyst 8510 CSR Example

InterVLAN Routing with the RSM Example

shows the network configuration for this example. There are three switches, one with an RSM installed in slot 5. The switches are connected through the Fast Ethernet uplink ports on the supervisor engines. Each switch has a 10/100-Mbps Fast Ethernet module in slot 3. Three hosts are connected to each switch, on ports 3/1, 3/2, and 3/3.

Figure 3-3 InterVLAN Routing with the RSM Example Configuration

These configuration tasks must be performed to configure the network in this example:

1 Configure Switch A as a VTP server and assign a VTP domain name.

2 Configure Switch B and Switch C as VTP clients and assign the same VTP domain name.

3 Configure ISL trunk links between the switches.

4 Create the VLANs on Switch A (the VLAN information is propagated to Switch B and Switch C through VTP).

5 Assign the switch ports on each switch to the appropriate VLAN.

6 On the RSM, create one VLAN interface for each VLAN configured on Switch A.

7 Assign IP addresses to the VLAN interfaces.

After you successfully configure the network, all end stations should be able to communicate with one another. Communication between hosts in the same VLAN is handled only by the switches. All interVLAN traffic must be routed by the RSM.

For example, if the VLAN 2 host on Floor 1 needs to communicate with the VLAN 3 host on Floor 1, the traffic must travel through all three switches to reach the RSM, where it is routed and sent back through all three switches to the destination host.

Switch A Configuration

This example shows how to configure Switch A: 

SwitchA> (enable) set trunk 1/1 desirable

Port(s) 1/1 trunk mode set to desirable.

SwitchA> (enable) %DTP-5-TRUNKPORTON:Port 1/1 has become isl trunk

%PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1

%PAGP-5-PORTFROMSTP:Port 1/1 left bridge port 1/1

%PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1


SwitchA> (enable) set vtp domain Corporate

VTP domain Corporate modified

SwitchA> (enable) set vtp mode server

VTP domain Corporate modified

SwitchA> (enable) set vlan 2 name Engineering

Vlan 2 configuration successful

SwitchA> (enable) set vlan 3 name Marketing

Vlan 3 configuration successful

SwitchA> (enable) set vlan 4 name Accounting

Vlan 4 configuration successful

SwitchA> (enable) set vlan 2 3/1

VLAN 2 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

2     3/1

SwitchA> (enable) set vlan 3 3/2

VLAN 3 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

3     3/2

SwitchA> (enable) set vlan 4 3/3

VLAN 4 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

4     3/3

SwitchA> (enable)

Switch B Configuration

This example shows how to configure Switch B: 

SwitchB> (enable) set trunk 1/2 desirable

Port(s) 1/2 trunk mode set to desirable.

SwitchB> (enable) %DTP-5-TRUNKPORTON:Port 1/2 has become isl trunk

%PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/2

%PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/2

%PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/2


SwitchB> (enable) set vtp domain Corporate

VTP domain Corporate modified

SwitchB> (enable) set vtp mode client

VTP domain Corporate modified

SwitchB> (enable) set vlan 2 3/1

VLAN 2 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

2     3/1

SwitchB> (enable) set vlan 3 3/2

Vlan 3 configuration successful

VLAN 3 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

3     3/2

SwitchB> (enable) set vlan 4 3/3

Vlan 4 configuration successful

VLAN 4 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

4     3/3

SwitchB> (enable)

Switch C Configuration

This example shows how to configure Switch C: 

SwitchB> (enable) set vtp domain Corporate

VTP domain Corporate modified

SwitchB> (enable) set vtp mode client

VTP domain Corporate modified

SwitchB> (enable) set vlan 2 3/1

VLAN 2 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

2     3/1

SwitchB> (enable) set vlan 3 3/2

Vlan 3 configuration successful

VLAN 3 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

3     3/2

SwitchB> (enable) set vlan 4 3/3

Vlan 4 configuration successful

VLAN 4 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

4     3/3

SwitchB> (enable)

RSM Configuration

This example shows how to configure the RSM: 

SwitchA> (enable) session 5

Trying Router-5...

Connected to Router-5.

Escape character is '^]'.

Router>enable

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#interface vlan 2

Router(config-if)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to down

Router(config-if)#ip address 172.20.52.33 255.255.255.224

Router(config-if)#no shutdown

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to up

Router(config-if)#interface vlan 3

Router(config-if)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan3, changed state to down

Router(config-if)#ip address 172.20.52.65 255.255.255.224

Router(config-if)#no shutdown

Router(config-if)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan3, changed state to up

Router(config-if)#

%LINK-3-UPDOWN: Interface Vlan3, changed state to up

Router(config-if)#interface vlan 4

Router(config-if)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan4, changed state to down

Router(config-if)#ip address 172.20.52.97 255.255.255.224

Router(config-if)#no shutdown

Router(config-if)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan4, changed state to up

Router(config-if)#

%LINK-3-UPDOWN: Interface Vlan4, changed state to up

Router(config-if)#exit

Router(config)#^Z

Router#

%SYS-5-CONFIG_I: Configured from console by vty0 (127.0.0.2)

Router#copy running-config startup-config

Building configuration...

[OK]

Router#

InterVLAN Routing with the RSFC Example

This example consists of these sections:

•Example Network Topology

•Catalyst 5509 Configuration

•Catalyst 5505 Configuration

•RSFC Configuration

Example Network Topology

shows the network configuration for this example. The network is configured as follows:

•There are three VLANs (IP subnets):

•VLAN 50 (172.16.50.0/24)

•VLAN 150 (172.16.150.0/24)

•VLAN 250 (172.16.250.0/24)

•Three VLAN interfaces are configured on the RSFC:

•Interface vlan50 (172.16.50.1)

•Interface vlan150 (172.16.150.1)

•Interface vlan250 (172.16.250.1)

•The Catalyst 5509 has the following hardware:

•Supervisor Engine III G with the RSFC in slot 1

•12-port 100-Mbps Fast Ethernet module in slot 2

•2-slot 48-port 10-Mbps Ethernet module in slot 6

•The Catalyst 5505 has the following hardware:

•Supervisor Engine III with Gigabit Ethernet uplink ports in slot 1

•2-slot 48-port 10-Mbps Ethernet module in slot 3

•The Catalyst 5509 and the Catalyst 5505 are connected through a Gigabit EtherChannel ISL trunk link on ports 1/1-2.

•The switches are VTP domain "Corporate"

•The Catalyst 5509 is the VTP server and the Catalyst 5505 is a VTP client

Figure 3-4 InterVLAN Routing with RSFC Example Network Topology

These configuration tasks must be performed to configure the network in this example:

1 Configure the Catalyst 5509 as a VTP server and assign a VTP domain name.

2 Configure the Catalyst 5505 as a VTP client in the same VTP domain.

3 Create the VLANs on the Catalyst 5509.

4 Configure the Gigabit EtherChannel ISL trunk link between the switches.

5 Assign the end station switch ports to the appropriate VLANs.

6 On the RSFC, create and assign IP addresses to the VLAN interfaces, one for each VLAN configured on the switch.

After you successfully configure the network, all end stations should be able to communicate with one another. Whenever an end station in one VLAN transmits to an end station in another VLAN, the traffic travels to the Catalyst 5509 and is passed to the RSFC on the appropriate VLAN interface. The RSFC checks the routing table, determines the correct outgoing VLAN interface, and sends the traffic out that interface to the Catalyst 5509. The Catalyst 5509 forwards the traffic out the appropriate switch port to the destination.

For example, if Host A transmits to the server, the Catalyst 5509 receives the traffic on port 6/1 and passes it to the RSFC on the VLAN 150 interface. The RSFC performs a routing table lookup and forwards the traffic out the VLAN 50 interface. The Catalyst 5509 forwards the traffic to the server out port 2/1.

Similarly, if Host B transmits to the server, the Catalyst 5505 receives the traffic on port 3/1 and passes it over the Gigabit EtherChannel ISL trunk link to the Catalyst 5509. The Catalyst 5509 passes the traffic to the RSFC over the VLAN 250 interface. The RSFC routes the traffic out the VLAN 50 interface and the Catalyst 5509 forwards the traffic to the server.

Catalyst 5509 Configuration

This example shows how to configure the Catalyst 5509: 

Cat5509> (enable) set VTP domain Corporate mode server

VTP domain Corporate modified

Cat5509> (enable) set vlan 50 

Vlan 50 configuration successful

Cat5509> (enable) set vlan 150

Vlan 150 configuration successful

Cat5509> (enable) set vlan 250

Vlan 250 configuration successful

Cat5509> (enable) set port channel 1/1-2 desirable

Port(s) 1/1-2 channel mode set to desirable.

Cat5509> (enable) set trunk 1/1 desirable isl

Port(s) 1/1 trunk mode set to desirable.

Port(s) 1/1 trunk type set to isl.

Cat5509> (enable) set port duplex 2/1 full

Port 2/1 set to full-duplex.

Cat5509> (enable) set vlan 50 2/1

VLAN 50 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

50    2/1

Cat5509> (enable) set port duplex 6/1 full

Port 6/1 set to full-duplex.

Cat5509> (enable) set vlan 150 6/1

VLAN 150 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

150   6/1

Cat5509> (enable)

Catalyst 5505 Configuration

This example shows how to configure the Catalyst 5505: 

Cat5505> (enable) set VTP domain Corporate mode client

VTP domain Corporate modified

Cat5509> (enable) set port duplex 3/1 full

Port 3/1 set to full-duplex.

Cat5505> (enable) set vlan 250 3/1

VLAN 250 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

250   3/1

Cat5505> (enable)

RSFC Configuration

This example shows how to configure the RSFC: 

Console> (enable) session 15

Trying Router-15...

Connected to Router-15.

Escape character is '^]'.


RSFC>enable 

RSFC#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

RSFC(config)#interface vlan50

RSFC(config-if)#ip address 172.16.50.1 255.255.255.0

RSFC(config-if)#no shutdown

RSFC(config-if)#interface vlan150

RSFC(config-if)#ip address 172.16.150.1 255.255.255.0

RSFC(config-if)#no shutdown

RSFC(config-if)#interface vlan250

RSFC(config-if)#ip address 172.16.250.1 255.255.255.0

RSFC(config-if)#no shutdown

RSFC(config-if)#^Z

RSFC#

Redundant RSFCs Using HSRP Example

This example consists of these sections:

•Example Network Topology

•RSFC A Configuration

•RSFC B Configuration

Example Network Topology

shows the network configuration for this example. The network is configured as follows:

•There are two VLANs (IP subnets):

•VLAN 100: 172.20.100.0/24

•VLAN 200: 172.20.200.0/24

•Two VLAN interfaces are configured on RSFC A:

•Interface vlan100 (172.20.100.1)

•Interface vlan200 (172.20.200.1)

•Two VLAN interfaces are configured on RSFC B:

•Interface vlan100 (172.20.100.2)

•Interface vlan200 (172.20.200.2)

•An HSRP IP address is allocated for each VLAN:

•VLAN 100: 172.20.100.10

•VLAN 200: 172.20.200.10

Figure 3-5 Redundant RSFCs Using HSRP Example Network Topology

The VLAN 100 and VLAN 200 interfaces on RSFC A are configured as the active HSRP interfaces for each VLAN (by setting the HSRP priority for the interfaces to 110). The VLAN 100 and VLAN 200 interfaces on RSFC B are configured as the standby HSRP router interfaces (by leaving the HSRP priority for the interfaces at the default value of 100).

Hosts in VLAN 100 are configured to use the VLAN 100 HSRP IP address (172.20.100.10) as their default gateway. Hosts in VLAN 200 are configured to use the VLAN 200 HSRP IP address (172.20.200.10) as their default gateway.

In this configuration, RSFC A actively routes traffic for the HSRP IP address and RSFC B provides transparent backup interfaces. In the event of a failure of the active supervisor engine or RSFC A, the standby interfaces on RSFC B become active and continue routing traffic from hosts using the HSRP IP address as their default gateway.

RSFC A Configuration

This example shows how to configure HSRP for RSFC A: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ip routing

Router(config)#router rip

Router(config-router)#network 172.20.0.0

Router(config-router)#interface vlan100

Router(config-if)#ip address 172.20.100.1 255.255.255.0

Router(config-if)#no shutdown

Router(config-if)#standby 100 ip 172.20.100.10

Router(config-if)#standby 100 priority 110

Router(config-if)#standby 100 preempt

Router(config-if)#standby 100 timers 5 15

Router(config-if)#standby 100 authentication Secret

Router(config-if)#interface vlan200

Router(config-if)#ip address 172.20.200.1 255.255.255.0

Router(config-if)#no shutdown

Router(config-if)#standby 200 ip 172.20.200.10

Router(config-if)#standby 200 priority 110

Router(config-if)#standby 200 preempt

Router(config-if)#standby 200 timers 5 15

Router(config-if)#standby 200 authentication Covert

Router(config-if)#^Z

Router#

RSFC B Configuration

This example shows how to configure HSRP for RSFC B: 

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ip routing

Router(config)#router rip

Router(config-router)#network 172.20.0.0

Router(config-router)#interface vlan100

Router(config-if)#ip address 172.20.100.2 255.255.255.0

Router(config-if)#no shutdown

Router(config-if)#standby 100 ip 172.20.100.10

Router(config-if)#standby 100 preempt

Router(config-if)#standby 100 timers 5 15

Router(config-if)#standby 100 authentication Secret

Router(config-if)#interface vlan200

Router(config-if)#ip address 172.20.200.2 255.255.255.0

Router(config-if)#no shutdown

Router(config-if)#standby 200 ip 172.20.200.10

Router(config-if)#standby 200 preempt

Router(config-if)#standby 200 timers 5 15

Router(config-if)#standby 200 authentication Covert

Router(config-if)#^Z

Router#

InterVLAN Routing with an External Cisco 7505 Router Example

shows the network configuration for this example. The switch has a 10/100-Mbps Fast Ethernet module in slot 2. Three hosts are connected to the switch, on ports 2/1, 2/2, and 2/3. The Cisco 7505 router has a Fast Ethernet interface processor in slot 2 and is connected to uplink port 1/1 on the switch supervisor engine.

Figure 3-6 InterVLAN Routing with External Cisco 7505 Example Configuration

These configuration tasks must be performed to configure the network in this example:

1 Configure the switch as a VTP server and assign a VTP domain name.

2 Create the VLANs on the switch.

3 Assign each switch port to the appropriate VLAN.

4 Configure the uplink port as an ISL trunk.

5 On the router, create three subinterfaces, one for each VLAN configured on the switch.

6 Configure ISL encapsulation for each VLAN on the appropriate subinterface.

7 Assign IP addresses to the VLAN interfaces.

After you successfully configure the network, all end stations should be able to communicate with one another. Whenever an end station in one VLAN transmits to an end station in another VLAN, the traffic travels over the trunk link to the router. The router checks the routing table, determines the correct outgoing subinterface, and sends the traffic back over the trunk link to the switch. The switch forwards the traffic out the appropriate switch port.

Switch Configuration

This example shows how to configure the switch: 

Switch> (enable) set vtp domain Corporate

VTP domain Corporate modified

Switch> (enable) set vtp mode server

VTP domain Corporate modified

Switch> (enable) set vlan 10

Vlan 10 configuration successful

Switch> (enable) set vlan 20

Vlan 20 configuration successful

Switch> (enable) set vlan 30

Vlan 30 configuration successful

Switch> (enable) set vlan 10 2/1

VLAN 10 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

10   2/1

Switch> (enable) set vlan 20 2/2

VLAN 20 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

20   2/2

Switch> (enable) set vlan 30 2/3

VLAN 30 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

30   2/3

Switch> (enable) set trunk 1/1 on

Port(s) 1/1 trunk mode set to on.

Cat5000> (enable)

Cisco 7505 Configuration

This example shows how to configure the router: 

Cisco7505#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Cisco7505(config)#interface fastethernet2/0.10

Cisco7505(config-subif)#encapsulation isl 10

Cisco7505(config-subif)#ip address 10.10.1.1 255.255.0.0

Cisco7505(config-subif)#interface fastethernet2/0.20

Cisco7505(config-subif)#encapsulation isl 20

Cisco7505(config-subif)#ip address 10.20.1.1 255.255.0.0

Cisco7505(config-subif)#interface fastethernet2/0.30

Cisco7505(config-subif)#encapsulation isl 30

Cisco7505(config-subif)#ip address 10.30.1.1 255.255.0.0

Cisco7505(config-subif)#^Z

Cisco7505#%SYS-5-CONFIG_I: Configured from console by console


Cisco7505#copy running-config startup-config

Building configuration...

[OK]

Cisco7505#

InterVLAN Routing with an External Catalyst 8510 CSR Example

shows the network configuration for this example. Switch A is a Catalyst 5000 switch with a two-slot 48-port 10/100-Mbps Fast Ethernet module in slot 3. Four hosts are connected to the switch, on ports 3/1, 3/2, 3/25, and 3/26. Switch B is a Catalyst 2926G switch. Two hosts are connected to the switch, on ports 2/1 and 2/2.

The Catalyst 8510 CSR has a 100BaseTX Fast Ethernet module in slot 0. Interfaces fastethernet0/0/0 and 0/0/1 are connected to supervisor engine uplink ports 1/1 and 1/2 on Switch A through a channeled ISL trunk. Interface fastethernet0/0/2 is connected to supervisor engine uplink port 1/1 on Switch B through an ISL trunk.

Figure 3-7 InterVLAN Routing with External Catalyst 8510 CSR Example Configuration

These configuration tasks must be performed to configure the network in this example:

1 Configure a port-channel interface on the Catalyst 8510 CSR to support the EtherChannel link to Switch A.

2 Assign the fastethernet0/0/0 and fastethernet0/0/1 interfaces to the port-channel interface.

3 Configure two subinterfaces on the port-channel interface, one for each VLAN configured on Switch A (VLANs 100 and 200).

4 Configure a subinterface on the fastethernet0/0/2 interface for the VLAN configured on Switch B (VLAN 300).

5 Configure ISL encapsulation on each subinterface.

6 Assign an IP address to each subinterface.

7 Configure Switch A as a VTP server and assign a VTP domain name.

8 Configure Switch B as a VTP server and assign it the same VTP domain name you configured on Switch A.

9 Create the VLANs (VLANs 100, 200, and 300) on both switches.

10 Assign the switch ports on each switch to the appropriate VLAN.

11 Configure a Fast EtherChannel bundle on the Switch A uplink ports.

12 Configure the EtherChannel as an ISL trunk.

13 Configure the Switch B uplink port as an ISL trunk.

After you successfully configure the network, all end stations should be able to communicate with one another. Whenever a station in one VLAN transmits to a station in another VLAN, the traffic travels over the trunk link to the router. The router checks the routing table, determines the correct outgoing subinterface, and sends the traffic out the appropriate subinterface. The switch forwards the traffic out the appropriate switch port.

Catalyst 8510 CSR Configuration

This example shows how to configure the Catalyst 8510 CSR: 

8510CSR#configure terminal

8510CSR(config)#interface port-channel1

8510CSR(config-if)#interface fa0/0/0

8510CSR(config-if)#channel-group 1


FastEthernet0/0/0 added as member-1 to port-channel1

8510CSR(config-if)#

00:20:20: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up

00:20:21: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state 
to up


8510CSR(config)#interface fa0/0/1

8510CSR(config-if)#channel-group 1


FastEthernet0/0/1 added as member-2 to port-channel1

8510CSR(config-if)#interface port-channel 1.100

8510CSR(config-subif)#encapsulation isl 100

8510CSR(config-subif)#ip address 172.20.52.33 255.255.255.224

8510CSR(config-subif)#interface port-channel 1.200

8510CSR(config-subif)#encapsulation isl 200

8510CSR(config-subif)#ip address 172.20.52.65 255.255.255.224

8510CSR(config-subif)#interface fa0/0/2

8510CSR(config-if)#interface fa0/0/2.300

8510CSR(config-subif)#encapsulation isl 300

8510CSR(config-subif)#ip address 172.20.52.97 255.255.255.224

8510CSR(config-subif)#^Z

8510CSR#

00:26:05: %SYS-5-CONFIG_I: Configured from console by console

8510CSR#

Switch A Configuration

This example shows how to configure Switch A: 

SwitchA> (enable) set port channel 1/1-2 on

Port(s) 1/1-2 channel mode set to on.

SwitchA> (enable) %PAGP-5-PORTFROMSTP:Port 1/1 left bridge port 1/1

%PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/2

%PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1-2

%PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/1-2


SwitchA> (enable) show port channel

Port  Status     Channel   Channel     Neighbor                  Neighbor

                 mode      status      device                    port

----- ---------- --------- ----------- ------------------------- ---------- 

 1/1  connected  on        channel     cisco C8510 8510CSR       FastEther 

 1/2  connected  on        channel     cisco C8510 8510CSR       FastEther 

----- ---------- --------- ----------- ------------------------- ---------- 

SwitchA> (enable) set trunk 1/1 on

Port(s) 1/1-2 trunk mode set to on.

SwitchA> (enable) %DTP-5-TRUNKPORTON:Port 1/1 has become isl trunk

%DTP-5-TRUNKPORTON:Port 1/2 has become isl trunk

%PAGP-5-PORTFROMSTP:Port 1/1 left bridge port 1/1-2

%PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/1-2

%PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1-2

%PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/1-2


SwitchA> (enable) show trunk 1/1

Port      Mode         Encapsulation  Status        Native vlan

--------  -----------  -------------  ------------  -----------

 1/1      on           isl            trunking      1


Port      Vlans allowed on trunk

--------  ---------------------------------------------------------------------

 1/1      1-1005


Port      Vlans allowed and active in management domain 

--------  ---------------------------------------------------------------------

 1/1      1


Port      Vlans in spanning tree forwarding state and not pruned

--------  ---------------------------------------------------------------------

 1/1 

SwitchA> (enable) set vtp domain Corporate mode server

VTP domain Corporate modified

SwitchA> (enable) set vlan 100

Vlan 100 configuration successful

SwitchA> (enable) set vlan 200

Vlan 200 configuration successful

SwitchA> (enable) set vlan 300

Vlan 300 configuration successful

SwitchA> (enable) set vlan 100 3/1-2

VLAN 100 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

%PAGP-5-PORTFROMSTP:Port 3/1 left bridge port 3/1

100   1/1-2

      3/1-2

SwitchA> (enable) %PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/2


SwitchA> (enable) %PAGP-5-PORTTOSTP:Port 3/1 joined bridge port 3/1

%PAGP-5-PORTTOSTP:Port 3/2 joined bridge port 3/2


SwitchA> (enable) set vlan 200 3/25-26

VLAN 200 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

200   1/1-2

      3/25-26

SwitchA> (enable) %PAGP-5-PORTFROMSTP:Port 3/25 left bridge port 3/25

%PAGP-5-PORTFROMSTP:Port 3/26 left bridge port 3/26

%PAGP-5-PORTTOSTP:Port 3/25 joined bridge port 3/25

%PAGP-5-PORTTOSTP:Port 3/26 joined bridge port 3/26


SwitchA> (enable)

Switch B Configuration

This example shows how to configure Switch B: 

SwitchB> (enable) set vtp domain Corporate mode server

VTP domain Corporate modified

SwitchB> (enable) set vlan 100

Vlan 100 configuration successful

SwitchB> (enable) set vlan 200

Vlan 200 configuration successful

SwitchB> (enable) set vlan 300

Vlan 300 configuration successful

SwitchB> (enable) set trunk 1/1 on

Port(s) 1/1 trunk mode set to on.

SwitchB> (enable) 01/15/1999,09:59:26:DTP-5:Port 1/1 has become isl trunk

01/15/1999,09:59:26:PAGP-5:Port 1/1 left bridge port 1/1.


SwitchB> (enable) 

SwitchB> (enable) 01/15/1999,09:59:37:PAGP-5:Port 1/1 joined bridge port 1/1.


SwitchB> (enable) set vlan 300 2/1-2

VLAN 300 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

300   1/1

      2/1-2

SwitchB> (enable)