ATM and Layer 3 Quick Software Configuration Guide, 12.1(5)EY1 - Configuring Layer 3 Features

Table Of Contents

Configuring Layer 3 Features

Configuring Ethernet Interfaces

Configuring Virtual LANs

Configuring IP Routing Protocols

Configuring IP Multicast Routing

Configuring Bridging

Configuring EtherChannel

Configuring Layer 3 Features

This chapter explains how to configure Layer 3 features, and includes the following sections:

• Configuring Ethernet Interfaces

• Configuring Virtual LANs

• Configuring IP Routing Protocols

• Configuring IP Multicast Routing

• Configuring Bridging

• Configuring EtherChannel

Note For more software configuration and command syntax information, refer to the Layer 3 Software Configuration Guide.

Configuring Ethernet Interfaces

Layer 3 switching supports Enhanced Gigabit Ethernet, Gigabit Ethernet, and Fast Ethernet interfaces. You can configure IP addresses, transmission speeds, and duplex modes on these interfaces.

Note Configure Enhanced Gigabit Ethernet interfaces in the same manner as Gigabit Ethernet interfaces.

Perform these steps:

Command

Purpose

Step 1

Switch> enable

Enters privileged EXEC mode.

Step 2

Switch# configure terminal

Switch(config)#

Enters global configuration mode.

Step 3

Switch(config)# interface {gigabitethernet | fastethernet} card/subcard/port

Switch(config-if)#

Enters Ethernet interface configuration mode to configure a Gigabit Ethernet or Fast Ethernet interface.

Step 4

Switch(config-if)# negotiation auto

or

Switch(config-if)# speed {10 | 100 | auto}

Switch(config-if)# duplex {full | half | auto}

Specifies the transmission speed and duplex negotiation mode for a Gigabit Ethernet interface.

or

Specifies the transmission speed and duplex mode for a Fast Ethernet interface.

Step 5

Switch(config-if)# ip address ip-address subnet-mask

Specifies the IP address and IP subnet mask to be assigned to the Ethernet interface.

Step 6

Switch(config-if)# exit

Switch(config)#

Returns to global configuration mode. Repeat Steps 3 to 5 to configure another Ethernet interface.

Step 7

Switch(config)# end

Returns to privileged EXEC mode.

Step 8

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

Saves your configuration changes to NVRAM.

Example
Switch> enable
Switch# configure terminal
Switch(config)# interface gigabitethernet 0/0/0
Switch(config-if)# negotiation auto
Switch(config-if)# ip address 10.1.2.3 255.0.0.0
Switch(config-if)# end
Switch# copy system:running-config nvram:startup-config
Verifying
Switch# show interface gigabitethernet 0/0/0
GigabitEthernet0/0/0 is administratively down, line protocol is down
  Hardware is K1 Gigabit Port, address is 00d0.ba1d.3207 (bia 00d0.ba1d.3207)
  Internet address is 10.1.2.3/8
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, rely 255/255, load 1/255
  Encapsulation ARPA, loopback not set, keepalive set (10 sec)
   Full-duplex mode, 1000Mb/s, Auto-negotiation, 1000BaseSX
Configuring 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.

Perform these steps:

Command

Purpose

Step 1

Switch> enable

Enters privileged EXEC mode.

Step 2

Switch# configure terminal

Switch(config)#

Enters global configuration mode.

Step 3

Switch(config)# interface {gigabitethernet | fastethernet} card/subcard/port.subinterface

Switch(config-subif)#

Enters subinterface configuration mode.

Step 4

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.

Step 5

Switch(config-subif)# bridge-group bridge-group

Assigns the subinterface a bridge group number.

Note When you are configuring VLAN routing, skip this step.

Step 6

Switch(config-subif)# interface {gigabitethernet | fastethernet} card/subcard/port

Switch(config-if)#

Enters interface configuration mode to configure the Ethernet main interface.

Step 7

Switch(config-if)# bridge-group bridge-group

Assigns the main interface to the bridge group.

Step 8

Switch(config-if)# exit

Switch(config)#

Returns to global configuration mode.

Step 9

Switch(config)# bridge bridge-group protocol ieee

Specifies that the bridge group will use the IEEE Ethernet Spanning Tree Protocol.

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(config)# 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>
!
Configuring IP Routing Protocols

IP routing is enabled by default on the switch router. For IP routing, you must configure the following values on the interface:

•Network address

•Subnetwork address

•IP subnet mask

You must also do the following global configurations:

•Select a routing protocol, such as the Enhanced Interior Gateway Routing Protocol (EIGRP) or the Routing Information Protocol (RIP).

•Assign IP network numbers without specifying subnet values.

Perform these steps for the routing protocol you want to configure:

Command

Purpose

Step 1

Switch(config-subif)# enable

Enters privileged EXEC mode.

Step 2

Switch(config-subif)# configure terminal

Switch(config-subif)#

Enters global configuration mode.

Step 3

Switch(config-if)# interfaceSwitch(config-if)# gigabitethernetSwitch(config)# fastethernetSwitch(config)# card/subcard/port

Switch(config-subif)#

Enters interface configuration mode.

Step 4

Switch(config-subif)# ip address ip-address subnet-mask

Assigns an IP address and IP subnet mask to the Ethernet interface.

Step 5

Switch(config-subif)# exit

Switch(config-if)#

Returns to global configuration mode.

Step 6

Switch(config-if)# router rip

Switch(config)#

Defines RIP as the routing protocol and starts the RIP routing process.

Step 7

Switch(config)# networkSwitch# network-number

Specifies the IP address of the network of directly connected networks. The routing process associates interfaces with the appropriate addresses, and begins processing packets on the specified network.

Step 8

Switch> exit

Switch#

Returns to global configuration mode.

Step 9

Switch(config)#router igrpSwitch(config)# autonomous-system-number

{)#

Defines IGRP¹ as the IP routing protocol.

The autonomous-system-number is the autonomous system to which this switch router belongs.

Step 10

| network} network-number

Defines the directly connected networks that run IGRP.

The network-number is the number of the network that is advertised by this switch router.

Step 11

Switch(config-if)#exit

Switch(config-if)#

Returns to global configuration mode.

Step 12

Switch(config-if)# router eigrp autonomous-system-number

Switch(config)#

Defines EIGRP as the IP routing protocol.

The autonomous-system-number is the autonomous system to which this switch router belongs.

Step 13

Switch(config)# networkSwitch(config-router)#network-number

Defines the directly connected networks that run EIGRP.

The network-number is the number of the network that is advertised by this switch router.

Step 14

Switch(config-router)# exit

Returns to global configuration mode.

Step 15

Switch(config-router)# router ospf process-id

Switch(config)#

Defines OSPF² as the IP routing protocol.

The process-id identifies a unique OSPF router process. This number is internal to the switch router only; the process ID does not have to match the process IDs on other routers.

Step 16

Switch(config)# network network-address wildcard-maskSwitch(config-routerareaSwitch(config-router)# area-id

Assigns an interface to a specific area.

The network-address is the address of directly connected networks or subnets.

The wildcard-mask is an inverse mask used to compare a given address with interface addressing, to determine whether OSPF will use this interface.

The area parameter identifies the interface as belonging to an area.

The area-id specifies the area associated with the network address.

Step 17

exit

Switch(config-router)#

Returns to global configuration mode.

Step 18

Switch(config)#router bgp autonomous-system

Switch(config)#

Define BGP³ as the routing protocol, and starts the BGP routing process.

Step 19

Switch(config-router)#networkSwitch(config-router)# network-number mask network-mask route-mapSwitch(config-router)# route-map-name

Flags a network as local to this autonomous system, and enters it into the BGP table.

Step 20

Switch(config)#exit

Switch(config)#

Returns to global configuration mode.

Step 21

Switch(config-router)#router isis

Defines IS-IS⁴ as the IP routing protocol.

Step 22

Switch(config-router)# net network-entity-title

Configures network entity titles (NETs) for the routing process; you can specify a name for a NET as well as an address.

Step 23

exit

Returns to global configuration mode.

Step 24

Switch(config-router)# interfaceSwitch(config)#gigabitethernetSwitch(config)# fastethernetSwitch(config-router)#card/subcard/port

Switch(config-router)#

Enters interface configuration mode.

Step 25

ip router isis tag

Specifies that this interface should run IS-IS.

Step 26

Switch(config-router)# end

Switch(config)#

Returns to privileged EXEC mode.

Step 27

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

Saves your configuration changes to NVRAM.

¹IGRP = Interior Gateway Routing Protocol

²OSPF = Open Shortest Path First

³BGP = Border Gateway Protocol

⁴IS-IS = Intermediate System-to-Intermediate System

Example
Switch> enable
Switch# configure terminal
Switch(config)# ip routing
Switch(config)# router rip
Switch(config-router)# network 192.168.1.1
Switch(config-router)# neighbor 192.168.2.1
Switch(config-router)# end
Switch# copy system:running-config nvram:startup-config

Verifying
Switch# show ip protocols
Routing Protocol is "rip"
  Sending updates every 30 seconds, next due in 18 seconds
  Invalid after 180 seconds, hold down 180, flushed after 240
  Outgoing update filter list for all interfaces is
  Incoming update filter list for all interfaces is
  Redistributing: rip
  Neighbor(s):
    192.168.2.1
  Default version control: send version 1, receive any version
  Routing for Networks:
    192.168.1.0
  Routing Information Sources:
    Gateway         Distance      Last Update
Distance: (default is 120)

Configuring IP Multicast Routing

IP multicast is a routing technique that allows IP traffic to be propagated from one source to a number of destinations, or from many sources to many destinations. Rather than sending one packet to each destination, one packet is sent to the multicast group identified by a single IP destination group address.

Perform these steps:

Command

Purpose

Step 1

Switch(config-router)# enable

Enters privileged EXEC mode.

Step 2

configure terminal

Switch(config-router)#

Enters global configuration mode.

Step 3

Switch(config)# ip multicast-routing

Enables IP multicast on the switch router.

Step 4

Switch(config)# interface {gigabitethernet | fastethernet} card/subcard/port

Switch(config-if)

Enters interface configuration mode.

Step 5

Switch(config-if)# ip address ip-address subnet-mask

Assigns an IP address and subnet mask to the interface.

Step 6

[ip pim]dense-mode Switch(config-if)# sparse-modeSwitch#sparse-dense-modeSwitch#

Enables IP multicast routing on the interface. You can specify dense mode, sparse mode, or sparse-dense mode (for internetworks that include both cases).

Step 7

Switch> end

Switch#

Returns to privileged EXEC mode.

Step 8

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

Saves your configuration changes to NVRAM.

Example
Switch> enable
Switch# configure terminal
Switch(config)# ip multicast-routing
Switch(config)# interface fastethernet 1/0/0
Switch(config-if)# ip address 192.168.1.1 255.255.255.0
Switch(config-if)# ip pim dense-mode
Switch(config-if)# end
Switch# copy system:running-config nvram:startup-config

Verify
8540MSR# more system:running-config
!
<Information deleted>
!
ip multicast-routing
!
<Information deleted>
!
interface FastEthernet1/0/0
 ip address 192.168.1.1 255.255.255.0
 ip pim dense-mode
!
<Information deleted>
!
Configuring Bridging

Cisco IOS software bridging functionality combines the advantages of a spanning tree bridge and a full multiprotocol router. This combination provides the speed and protocol transparency of an adaptive spanning tree bridge, along with the functionality, reliability, and security of a router. Cisco IOS software supports transparent bridging for Ethernet.

Perform these steps:

Command

Purpose

Step 1

Switch(config)#enable

Enters privileged EXEC mode.

Step 2

Switch(config)# configure terminal

{

Enters global configuration mode.

Step 3

| bridge} bridge-groupSwitch(config-if)protocol ieee

Assigns a bridge group number, and defines a IEEE 802.1D standard Spanning Tree Protocol.

Step 4

Switch(config-if)# bridgeSwitch(config-if)# bridge-group [priority| number

Assigns a specific priority to the bridge, which assists the definition of the spanning tree root. The lower the priority, the more likely the bridge will be selected as the root. (Optional)

Step 5

| interface]gigabitethernetSwitch(config-router)# fastethernetSwitch#card/subcard/port

Switch#

Enters interface configuration mode to configure the interface.

Step 6

bridge-groupSwitch> bridge-group

Assigns a network interface to a bridge group.

Step 7

Switch# bridge-groupSwitch(config)#bridge-groupSwitch(config)#path-cost value

Assigns a specific path cost to the bridged interface, which assists the definition of the spanning tree root. The lower the path-cost value, the more likely the bridge is selected as the root. (Optional)

Step 8

exit

Switch(config)#

Returns to global configuration mode. Repeat Steps 5 to 7 to assign additional interfaces to a bridge group.

Step 9

end

Returns to privileged EXEC mode.

Step 10

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)# bridge 5 protocol ieee
Switch(config)# bridge 5 priority 100
Switch(config)# interface gigabitethernet 0/0/7 
Switch(config-if)# bridge-group 5
Switch(config-if)# bridge-group 5 path-cost 250
Switch(config-if)# end
Switch# copy system:running-config nvram:startup-config
Verify
Switch# show bridge group
Bridge Group 5 is running the IEEE compatible Spanning Tree protocol
      Port 13 (GigabitEthernet0/0/7) of bridge group 5 is down 
Switch# more system:running-config
Building configuration...
!
<Information deleted>
!
interface GigabitEthernet0/0/7
 no ip address
 no ip directed-broadcast
 no ip route-cache cef
 no ip route-cache
 no ip mroute-cache
 shutdown
 bridge-group 5
 bridge-group 5 path-cost 250
 bridge-group 5 spanning-disabled
end
Configuring EtherChannel

EtherChannel is a trunking technology that groups together multiple full-duplex 802.3 Ethernet interfaces to provide fault-tolerant high-speed links between switches, routers, and servers. 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 (for example, connectivity to a Catalyst 5500 switch).

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.

Note 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.

Perform these steps:

Command

Purpose

Step 1

Switch(config)# enable

Enters privileged EXEC mode.

Step 2

{configure terminal

|

Enters global configuration mode.

Step 3

} interfaceSwitch(config-if)port-channelSwitch(config-if)#channel-number

Creates the EtherChannel interface and enters interface configuration mode. The channel number can be from 1 to 64 for FECs and GECs.

Step 4

Switch(config-if)# ip address ip-address subnet-mask

Assigns an IP address and subnet mask to the EtherChannel interface.

Step 5

no shutdown

Enables the EtherChannel interface.

Step 6

exit

Exits interface configuration mode. Optionally, you can remain in interface configuration mode and enable other supported interface commands to meet your requirements.

Step 7

Switch(config-if)# interfaceSwitch(config)#gigabitethernetSwitch(config)# fastethernetSwitch#card/subcard/port

Switch#

Enters interface configuration mode.

Step 8

Switch> 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.

Step 9

Switch# channel-groupSwitch(config)#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.

Step 10

Switch(config)# exit

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.

Step 11

end

Switch(config-if)#

Returns to privileged EXEC mode.

Step 12

Switch(config-if)# 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
Verify
Switch# more system:running-config
Building configuration...
Current configuration:
!
<Information deleted>
!
interface FastEthernet1/0/2
 no ip address
 no ip directed-broadcast
 no ip mroute-cache
 channel-group 5
end
!
<Information deleted>
!
interface Port-channel5
 ip address 209.165.200.225 255.255.255.224
 no ip directed-broadcast
 hold-queue 300 in
end 
!
<Information deleted>
!