About Layer 3 Switching Interfaces

Chapter 4 Configuring Interfaces

Step 3 Follow each interface command with the interface configuration commands required for your particular interface.

The commands you enter define the protocols and applications that will run on the interface. The commands are collected and applied to the interface command until you enter another interface command, a command that is not an interface configuration command, or you enter end to return to privileged EXEC mode.

Step 4 Check the status of the configured interface by using the EXEC show commands.

Router# show interface gigabitethernet 1/0/1 GigabitEthernet1/0/1 is up, line protocol is up

Hardware is K1 Gigabit Port, address is 00d0.ba1d.3207 (bia 00d0.ba1d.3207) 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

output flow-control is unsupported, input flow-control is unsupported ARP type: ARPA, ARP Timeout 04:00:00

Layer 3 switching supports two different Gigabit Ethernet interfaces, an eight-port module and a two-port module. This section describes the initial configurations for both interface types.

Tips Before you configure interfaces, be sure to have the interface network (IP or IPX) addresses and the corresponding subnet mask information. If you do not have this information, consult your network administrator.

The Gigabit Ethernet interface modules can be configured as trunk ports, non-trunking ports, routed ports, or bridged ports. The trunk ports employ 802.1Q encapsulation; Inter-Switch Link (ISL) is not supported. You can use the Gigabit Ethernet ports as routed interfaces, or you can configure the ports into a bridge group, which is the recommended configuration.

By configuring as many ports as possible in a bridge group, you can optimize the throughput of your switch router. You can also ensure that your networks are routed by using integrated routing and bridging features from Cisco IOS software. For configuration instructions, see the “About Integrated Routing and Bridging” section on page 6-4.

Between ports on the eight-port Gigabit Ethernet interface module itself, local switching at Layer 2 provides nonblocking performance at wire speed. For ports on this module configured as a bridge group, Layer 2 traffic is processed at full Gigabit Ethernet rates. For Layer 3 traffic, however, this interface module provides 2-Gbps routing bandwidth from the switch fabric.

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