Configuring LAN Interfaces

To specify an Ethernet interface and enter interface configuration mode, use one of the following commands in global configuration mode.

Router(config)# interface ethernet  number

Router(config)# interface ethernet  slot / port

Router(config)# interface ethernet slot / port-adapter / port 

Router(config)# interface fastethernet number

Router(config)# interface fastethernet slot / port 

Router(config)# interface fastethernet slot / port-adapter / port

Router(config)# interface gigabitethernet slot / port 

To display the Fast Ethernet slots and ports, use the show interfaces fastethernetcommand. The Fast Ethernet network interface module (NIM) and the Fast Ethernet Interface Processor (FEIP) default to half-duplex mode.

Currently, there are three common Ethernet encapsulation methods:

• The standard Advanced Research Projects Agency (ARPA) Ethernet Version 2.0 encapsulation, which uses a 16-bit protocol type code (the default encapsulation method).
• Service access point (SAP) IEEE 802.3 encapsulation, in which the type code becomes the frame length for the IEEE 802.2 LLC encapsulation (destination and source Service Access Points, and a control byte).
• The SNAP method, as specified in RFC 1042, >Standard for the Transmission of IP Datagrams Over IEEE 802 Networks , which allows Ethernet protocols to run on IEEE 802.2 media.

The encapsulation method that you use depends upon the routing protocol that you are using, the type of Ethernet media connected to the router or access server, and the routing or bridging application that you configure.

To establish Ethernet encapsulation of IP packets, use one of the following commands in interface configuration mode.

Router(config-if)# encapsulation arpa

Router(config-if)# encapsulation sap 

Router(config-if)# encapsulation snap

For an example of selecting Ethernet encapsulation for IP, see the Ethernet Encapsulation Enablement Example.

The default is half-duplex mode on the FEIP2-DSW-2FX. To enable full-duplex mode on the FEIP2-DSW-2FX (for a maximum aggregate bandwidth of 200 Mbps), use either of the following commands in interface configuration mode.

Router(config-if)# full-duplex

Router(config-if)# no half-duplex

For an example of enabling full-duplex mode on Fast Ethernet, see the Full-Duplex Enablement Operation Example.

Caution

To prevent system problems, do not configure both FEIP2-DSW-2FX interfaces for full-duplex operation at the same time. The FEIP2-DSW-2TX supports half-duplex only and should not be configured for full-duplex.

You can specify that the Ethernet network interface module (NIM) on the Cisco 4000 series routers use either the default of an attachment unit interface (AUI) and a 15-pin connector, or 10BASE-T and an RJ-45 connector. To do so, use one of the following commands in interface configuration mode.

Router(config-if)# media-type aui 

Router(config-if)# media-type 10baset

The default media connector type is an RJ-45 or SC (fiber-optic) connector. You can specify that the interface uses either an MII connector, or an RJ-45 or SC (fiber-optic) connector (this is the default). To do so, use one of the following commands in interface configuration mode.

Router(config-if)# media-type mii 

Router(config-if)# media-type 100basex

Note	When using the I/O controller that is equipped with an MII receptacle and an RJ-45 receptacle, only one receptacle can be configured for use at a time.

On a Cisco 4000 series or Cisco 4500 series routers, you can extend the twisted-pair 10BASE-T capability beyond the standard 100 meters by reducing the squelch (signal cutoff time). This feature applies only to the LANCE controller 10BASE-T interfaces. LANCE is the AMD controller chip for the Cisco 4000 and Cisco 4500 Ethernet interface and does not apply to the Fast Ethernet interface.

To reduce squelch, use the first command in the following table in interface configuration mode. You can later restore the squelch by using the second command.

Router(config-if)# squelch reduced 

Router(config-if)# squelch normal 

1.    Router# configure terminal

2.    Router(config)# interface fastethernet number

3.    Router(config-if)# ip address address subnet-mask

4.    Router(config-if)# speed {10 | 100 | auto}

5.    Router(config-if)# duplex {full | half | auto}

To use the autonegotiation capability (that is, to detect speed and duplex modes automatically), you must set both speed and duplex command to auto. Setting the speed command to auto negotiates speed only, and setting duplex command to auto negotiates duplex only. The table below describes the performance of the access server for different combinations of the duplex and speed command options. The specified duplex command option plus the specified speed command option produces the resulting system action.

Router(config-if)# duplex auto

                  
                    speed auto
                

Router(config-if)# duplex auto

                  
                    speed 10 or speed 100

Router(config-if)# duplex half 

Router(config-if)# duplex full

                  
                    speed auto
                

Router(config-if)# duplex half 

                  
                    speed 10
                

Router(config-if)# duplex full

                  
                    speed 10
                

Router(config-if)# duplex half 

                  
                    speed 100
                

Router(config-if)# duplex full

                  
                    speed 100
                

The PA-12E/2FE Ethernet switch port adapter provides Cisco 7200 series routers with up to twelve 10-Mbps and two 10/100-Mbps switched Ethernet (10BASE-T) and Fast Ethernet (100BASE-TX) interfaces for an aggregate bandwidth of 435 Mbps, full-duplex. The PA-12E/2FE port adapter supports the Ethernet, IEEE 802.3, and IEEE 802.3u specifications for 10-Mbps and 100-Mbps transmission over unshielded twisted pair (UTP) cables.

The PA-12E/2FE port adapter offloads Layer 2 switching from the host CPU by using store-and-forward or cut-through switching technology between interfaces within the same virtual LAN (VLAN) on the PA-12E/2FE port adapter. The PA-12E/2FE port adapter supports up to four VLANs (bridge groups).

Note	The PA-12E/2FE port adapter is a dual-width port adapter, which means it occupies two horizontally aligned port adapter slots when installed in a Cisco 7200 series router. (Single-width port adapters occupy individual port adapter slots in a Cisco 7200 series router.)

All interfaces on the PA-12E/2FE port adapter support autosensing and autonegotiation of the proper transmission mode (half-duplex or full-duplex) with an attached device. The first two PA-12E/2FE interfaces (port 0 and port 1) also support autosensing and autonegotiation of the proper connection speed (10 Mbps or 100 Mbps) with an attached device. If an attached device does not support autosensing and autonegotiation of the proper transmission mode, the PA-12E/2FE interfaces attached to the device automatically enter half-duplex mode. Use the show system:running-configcommand to determine if a PA-12E/2FE interface is autosensing and autonegotiating the proper transmission mode with an attached device. Use the full-duplexand the half-duplex commands to change the transmission mode of a PA-12E/2FE interface. After changing the transmission mode, use the show interfacescommand to verify the transmission mode of the interface.

Note

If you use the full-duplexand the half-duplex commands to change the transmission mode of the first two PA-12E/2FE interfaces (port 0 and port 1), the transmission speed of the two PA-12E/2FE interfaces automatically defaults to 100-Mbps. The first two PA-12E/2FE interfaces operate only at 10 Mbps when the interfaces are autosensing and autonegotiating the proper connection speed (10 Mbps or 100 Mbps) with an attached device.

To configure the PA-12E/2FE port adapter, perform the tasks in the following sections. Each task in the list is identified as either required or optional.

Note

If you plan to use a PA-12E/2FE interface to boot from a network (using TFTP), ensure that the interface is configured for a loop-free environment, that an IP address is configured for the interface's bridge-group virtual interface, and that system boot image 11.2(10)P is installed on your router (use the show version command to view the system boot image of your router). Then, before booting from the network server, use the bridge-group bridge-group number spanning-disabled command to disable the Spanning Tree Protocol configured on the interface to keep the TFTP server from timing out and closing the session. For detailed information about booting from a network using TFTP, loading a system image from a network server, and configuring the Spanning Tree Protocol on your Cisco 7200 series router, refer to the PA-12E/2FE Ethernet Switch Port Adapter book that accompanies the hardware and to the Cisco IOS Bridging and IBM Networking Configuration Guide.

For information on other commands that can be used to configure a PA-12E/2FE port adapter, refer to the CiscoIOS Interface and Hardware Component Command Reference . For information on bridging, refer to the "Configuring Transparent Bridging" chapter in the CiscoIOS Bridging and IBM Networking Configuration Guide .

For PA-12E/2FE port adapter configuration examples, see the PA-12E 2FE Port Configuration Examples.

• Configuring the PA-12E 2FE Port Adapter
• Configuring the PA-12E 2FE Port Adapter
• Monitoring and Maintaining the PA-12E 2FE Port Adapter
• Configuring Bridge Groups Using the 12E 2FE VLAN Configuration WebTool

1.   Do one of the following:

2.    Router(config-if)# ip address ip-address mask

3.    Router(config-if)# frame-type ethernet

Note	The port number for the 100VG-AnyLAN port adapter is always 0.

Configuring the PA-100VG interface is similar to configuring an Ethernet or Fast Ethernet interface. To display information about the 100VG-AnyLAN port adapter, use the show interfaces vg-anylan EXEC command.

1.    Router# configure terminal

2.    Router(config)# interface fastethernet slot / port²

3.    Router(config)# duplex full

1.    Router# configure terminal

2.    Router(Config)# interface ethernet slot / port³

3.    Router(Config-if)# interface fastethernet slot / port⁴

4.    Router(Config-if)# speed 10

1.    Router# configure terminal

2.    Router(config)# interface ethernet slot / port⁵

3.    Router(config)# interface fastethernet slot / port⁶

4.    Router(config)# interface gigabitethernet slot / port⁷

5.    Router(config-if) # ip address ip-address mask

6.    Router(config-if)# duplex auto

7.    Router#(config-if)# Exit

Use the show interfaces {ethernet | fastethernet | gigabitethernet} command to verify that the interface and line protocol are in the correct state (up) and that the transmission mode is configured on the interface. You can configure full, half, or auto transmission mode for Ethernet and Fast Ethernet interfaces. You can configure forced transmission mode for Gigabit Ethernet interfaces. The following is sample output from the show interfaces gigabitethernet command.

Router# show interfaces gigabitethernet 0/0
GigabitEthernet0/0 is up, line protocol is up 
   Hardware is 82543 (Livengood), address is 00d0.ffb6.4c00 (bia 00d0.ffb6.4c00)
   Internet address is 10.1.1.0/0
   MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, 
      reliability 255/255, txload 1/255, rxload 1/255
   Encapsulation ARPA, loopback not set
   Keepalive set (10 sec)
   Full-duplex mode, link type is autonegotiation, media type is SX
   output flow-control is on, input flow-control is on
   ARP type:ARPA, ARP Timeout 04:00:00
   Last input 00:00:04, output 00:00:03, output hang never
   Last clearing of "show interface" counters never
   Queueing strategy:fifo
   Output queue 0/40, 0 drops; input queue 0/75, 0 drops
   5 minute input rate 0 bits/sec, 0 packets/sec
   5 minute output rate 0 bits/sec, 0 packets/sec
      2252 packets input, 135120 bytes, 0 no buffer
      Received 2252 broadcasts, 0 runts, 0 giants, 0 throttles
      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
      0 watchdog, 0 multicast, 0 pause input
      0 input packets with dribble condition detected
      2631 packets output, 268395 bytes, 0 underruns
      0 output errors, 0 collisions, 2 interface resets
      0 babbles, 0 late collision, 0 deferred
      0 lost carrier, 0 no carrier, 0 pause output
      0 output buffer failures, 0 output buffers swapped out

To monitor and maintain the Gigabit Ethernet or Ethernet interfaces on the Cisco 7200-I/O-GE+E, use the following commands in privileged EXEC mode.

Router# show controllers ethernet

Router# show interfaces ethernet slot/port8

Router# show controllers gigabitethernet

Router# show interfaces gigabitethernet slot/port9

To monitor and maintain the Fast Ethernet or Ethernet interfaces on the Cisco 7200-I/O-2FE/E, use the following commands in privileged EXEC mode.

Router# show controllers ethernet

Router# show interfaces ethernet slot/port10

Router# show controllers fastethernet

Router# show interfaces fastethernet

1.    Router(config)# interface port-channel channel-number

2.    Router(config-if)# ip address ip-address mask

3.    Router(config-if)# mac-addressieee-address

4.    Router(config-if)# end

5.    Router# show interface port-channel

Note	If you want to use the Cisco Discovery Protocol (CDP), you must configure it on the physical Ethernet, Fast Ethernet, or Gigabit Ethernet interface, not on the port-channel interface.

Caution

With Release 11.1(20)CC and later, Fast EtherChannel supports CEF/dCEF. We recommend that you clear all explicit ip route-cache distributed commands from the Fast Ethernet interfaces before enabling dCEF on the port-channel interface. Doing this gives the port-channel interface proper control of its physical Fast Ethernet links. When you enable CEF/dCEF globally, all interfaces that support CEF/dCEF are enabled. When CEF/dCEF is enabled on the port-channel interface, it is automatically enabled on each of the Fast Ethernet interfaces in the channel group. However, if you have previously disabled CEF/dCEF on the Fast Ethernet interface, CEF/dCEF is not automatically enabled. In this case, you must enable CEF/dCEF on the Fast Ethernet interface.

1.    Router(config)# interface fastethernet slot / port

2.    Router(config-if)# no ip address

3.    Router(config-if)# channel-group channel-number

4.    Router(config-if)# exit

5.    Router(config-if)# end

6.    Router(config)# show interfaces port-channel

Caution

The port-channel interface is the routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet interfaces. Do not assign bridge groups on the physical Fast Ethernet interfaces because it creates loops. Also, you must disable spanning tree.

To remove a Fast Ethernet interface from a Fast EtherChannel, use the following commands beginning in global configuration mode.

1.    Router(config)# interface fastethernet slot / port

2.    Router(config-if)# no channel-group

3.    Router(config-if)# end

The Cisco IOS software automatically removes a Fast Ethernet interface from the Fast EtherChannel if the interface goes down, and the software automatically adds the Fast Ethernet interface to the Fast EtherChannel when the interface is back up.

Currently, Fast EtherChannel relies on keepalives to detect whether the line protocol is up or down. Keepalives are enabled by default on the Fast Ethernet interfaces. If the line protocol on the interface goes down because it did not receive a keepalive signal, the Fast EtherChannel detects that the line protocol is down and removes the interface from the Fast EtherChannel. However, if the line protocol remains up because keepalives are disabled on the Fast Ethernet interface, the Fast EtherChannel cannot detect this link failure (other than a cable disconnect) and does not remove the interface from the Fast EtherChannel even if the line protocol goes down. This can result in unpredictable behavior. The implementation of the Port Aggregation Protocol in a subsequent release of this feature will remove the dependency on keepalives.

See the LAN Interface Configuration Examples for configuration examples.

You can monitor the status of the Fast EtherChannel interface by using the show interfaces port-channel EXEC command.

1.    Router(config)# interface gigabitethernet slot / port

2.    Router(config-if)# no ip address

3.    Router(config-if)# channel-group channel-number

4.    Router(config-if)# exit

5.    Router(config-if)# end

6.    Router(config)# show interfaces port-channel

1.    Router(config)# interface gigabitethernet slot / port

2.    Router(config-if)# no channel-group

3.    Router(config-if)# end

You can monitor the status of the Gigabit EtherChannel interface by using the show interfaces port-channel EXEC command.

To specify a FDDI interface and enter interface configuration mode, use one of the following commands in global configuration mode.

Router(config)# interface fddi  number

Router(config)# interface fddi  slot / port

By default, Cisco FDDI uses the SNAP encapsulation format defined in RFC 1042. It is not necessary to define an encapsulation method for this interface when using the FIP.

FIP fully supports transparent and translational bridging for the following configurations:

• FDDI-to-FDDI
• FDDI-to-Ethernet
• FDDI-to-Token Ring

Enabling FDDI bridging encapsulation places the FIP into encapsulation mode when doing bridging. In transparent mode, the FIP interoperates with earlier versions of encapsulating interfaces when performing bridging functions on the same ring. When using the FIP, you can specify the encapsulation method by using the following command in interface configuration mode.

Router(config-if)# fddi encapsulate

When you are doing translational bridging, use routing for routable protocols and use translational bridging for the rest, such as local-area transport (LAT).

Note

Bridging between dissimilar media presents several problems that can prevent communications. These problems include bit-order translation (using MAC addresses as data), maximum transfer unit (MTU) differences, frame status differences, and multicast address usage. Some or all of these problems might be present in a multimedia-bridged LAN and might prevent communication. These problems are most prevalent in networks that bridge between Token Ring and Ethernet networks or between Token Ring and FDDI because of the different ways that Token Ring is implemented by the end nodes.

We are currently aware of problems with the following protocols when bridged between Token Ring and other media: AppleTalk, DECnet, IP, Novell IPX, Phase IV, VINES, and XNS. Further, the following protocols might have problems when bridged between FDDI and other media: Novell IPX and XNS. We recommend that these protocols be routed whenever possible.

To enable full-duplex mode on the PA-F/FD-SM and PA-F/FD-MM port adapters, use one of the following commands in interface configuration mode.

Router(config-if)# full-duplex

Router(config-if)# no half-duplex

You can set the FDDI token rotation time to control ring scheduling during normal operation and to detect and recover from serious ring error situations. To do so, use the following command in interface configuration mode.

Router(config-if)# fddi token-rotation-time  microseconds

The FDDI standard restricts the allowed time to greater than 4000 microseconds and less than 165,000 microseconds. As defined in the X3T9.5 specification, the value remaining in the token rotation timer (TRT) is loaded into the token holding timer (THT). Combining the values of these two timers provides the means to determine the amount of bandwidth available for subsequent transmissions.

You can set the transmission timer to recover from a transient ring error by using the following command in interface configuration mode.

Router(config-if)# fddi valid-transmission-time  microseconds

You can set the FDDI control transmission timer to control the FDDI TL-Min time, which is the minimum time to transmit a Physical Sublayer or PHY line state before advancing to the next Physical Connection Management or PCM state as defined by the X3T9.5 specification. To do so, use the following command in interface configuration mode.

Router(config-if)# fddi tl-min-time  microseconds

You can modify the C-Min timer on the PCM from its default value of 1600 microseconds by using the following command in interface configuration mode.

Router(config-if)# fddi c-min  microseconds

You can change the TB-Min timer in the PCM from its default value of 100 milliseconds. To do so, use the following command in interface configuration mode.

Router(config-if)# fddi tb-min  milliseconds

You can change the FDDI timeout timer in the PCM from its default value of 100 ms. To do so, use the following command in interface configuration mode.

Router(config-if)# fddi t-out  milliseconds

You can disable and enable SMT frame processing for diagnostic purposes. To do so, use one of the following commands in interface configuration mode.

Router(config-if)# no fddi smt-frames

Router(config-if)# fddi smt-frames

You can enable the duplicate address detection capability on the FDDI. If the FDDI finds a duplicate address, it displays an error message and shuts down the interface. To enable duplicate address checking, use the following command in interface configuration mode.

Router(config-if)# fddi duplicate-address-check

You can set the FDDI bit control to control the information transmitted during the Connection Management (CMT) signaling phase. To do so, use the following command in interface configuration mode.

Router(config-if)# fddi cmt-signal-bits  signal-bits 
[phy-a | phy-b]

You can control whether the CMT onboard functions are on or off. The FIP provides CMT functions in microcode. These functions are separate from those provided on the processor card and are accessed through EXEC commands.

The default is for the FIP CMT functions to be on. A typical reason to disable these functions is when you work with new FDDI equipment and have problems bringing up the ring. If you disable the CMT microcode, the following actions occur:

• The FIP CMT microcode is disabled.
• The main system code performs the CMT function while debugging output is generated.

To disable the CMT microcode, use the following command in interface configuration mode.

Router(config-if)# no fddi if-cmt

In normal operation, the FDDI interface is operational once the interface is connected and configured. You can start and stop the processes that perform the CMT function and allow the ring on one fiber to be stopped. To do so, use either of the following commands in EXEC mode.

Router# cmt connect [interface-name [phy-a | phy-b]]

Router# cmt disconnect [interface-name [phy-a | phy-b]]

Do not use either of the preceding commands during normal operation of FDDI; they are used during interoperability tests.

1.    Router# configure terminal

2.    Router(config)# interface fddi number

3.    Router(config-if)# fddi number

4.    Router(config-if)# fddi frames-per-token number

5.    Router(config-if)# fddi frames-per-token number

You can set the maximum number of unprocessed FDDI Station Management (SMT) frames that will be held for processing. Setting this number is useful if the router that you are configuring gets bursts of messages that arrive faster than the router can process. To set the number of frames, use the following command in global configuration mode.

Router(config)# smt-queue-threshold  number

The FCI card preallocates three buffers to handle bursty FDDI traffic (for example, Network File System (NFS) bursty traffic). You can change the number of preallocated buffers use the following command in interface configuration mode.

Router(config-if)# fddi burst-count

To specify a Token Ring interface and enter interface configuration mode, use one of the following commands in global configuration mode.

Router(config)# interface tokenring  number

Router(config)# interface tokenring  slot / port

Router(config)# interface tokenring  slot / port-adapter / port

Cisco Token Ring interfaces support early token release, a method whereby the interface releases the token back onto the ring immediately after transmitting rather than waiting for the frame to return. This feature can help to increase the total bandwidth of the Token Ring. To configure the interface for early token release, use the following command in interface configuration mode.

Router(config-if)# early-token-release

The Token Ring interface on the AccessPro PC card can be managed by a remote LAN manager over the PCbus interface. Currently, the LanOptics Hub Networking Management software running on an IBM-compatible PC is supported.

To enable LanOptics Hub Networking Management of a PCbus Token Ring interface, use the following command in interface configuration mode.

Router(config-if)# local-lnm

To enable an interface to operate as a concentrator port, use the following command in interface configuration mode.

Router(config-if)# port

To monitor the Token Ring concentrator port, use one or more of the following commands in EXEC mode.

Router# show controllers token

Router# show interfaces token

The following example configures the Gigabit Ethernet interface on the Cisco 7200-I/O-GE+E. The following commands are configured on slot 0, port 0.

Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# interface gigabitethernet 0/0
Router(config-if)# ip address 10.1.1.10 255.255.255.252
Router(config-if)# negotiation auto
Router(config-if)# end

The following example configures the Fast Ethernet interface on the Cisco 7200-I/O-2FE/E for fully enabled autonegotiation:

Router# 
configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# interface fastethernet 0/0
Router(config-if)# 
duplex auto
Router(config-if)# speed auto

The following example configures port 1 on hub 0 of Ethernet interface 0:

hub ethernet 0 1
 no shutdown

The following example configures ports 1 through 8 on hub 0 of Ethernet interface 0:

hub ethernet 0 1 8
 no shutdown

The following example configures the hub to allow only packets from MAC address 1111.2222.3333 on port 2 of hub 0:

hub ethernet 0 2
 source-address 1111.2222.3333

The following example configures the hub to remember the first MAC address received on port 2 and allow only packets from that learned MAC address:

hub ethernet 0 2
 source-address

The following example shuts down ports 3 through 5 on hub 0:

hub ethernet 0 3 5
 shutdown

The following example shuts down port 3 on hub 0:

hub ethernet 0 3
 shutdown

The following example specifies the gateway IP address and enables an SNMP trap to be issued to the host 172.16.40.51 when a MAC address violation is detected on hub ports 2, 3, or 4. It specifies that Ethernet interface 0 is the source for all traps on the router. The community string is defined as the string public and the read/write parameter is set.

ip route 0.0.0.0 0.0.0.0 172.22.10.1
snmp-server community public rw
snmp-server trap-source ethernet 0
snmp-server host 172.16.40.51 public
hub ethernet 0 2 4
snmp trap illegal-address