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

Use the show interfaces fastethernet command to display the Fast Ethernet slots and ports. The Fast Ethernet NIM and the FEIP default to half-duplex mode.

Currently, there are three common Ethernet encapsulation methods:

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

Establish Ethernet encapsulation of IP packets by using one of the following commands in interface configuration mode:

For an example of selecting Ethernet encapsulation for IP, see the section "Enabling Ethernet Encapsulation Example" later in this chapter.

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 one of the following commands in interface configuration mode:

For an example of how to enable full-duplex mode on Fast Ethernet, see the section "Enabling Full-Duplex Operation Example" later in this chapter.

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

The default media connector type is an RJ-45 or SC (fiber-optic) connector. You can specify that the interface use 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:

On Cisco 4000 series or Cisco 4500 series routers, you can extend the twisted-pair 10BaseT capability beyond the standard 100 meters by reducing the squelch (signal cutoff time). This feature applies only to the LANCE controller 10BaseT interfaces. LANCE is the AMD controller chip for the Cisco 4000 and Cisco 4500 Ethernet interface.

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

You must configure the Fast Ethernet 100BaseT interface on a Cisco AS5300 so that it can be recognized as a device on the Ethernet LAN. The Fast Ethernet interface supports 10-and 100-Mbps speeds with the 100BaseT and 10BaseT routers, hubs, and switches.

To configure the interface, use the following commands, beginning in privileged EXEC mode:

To use the autonegotiation capability (that is, to detect speed and duplex modes automatically), you must set both speed and duplex to auto. Setting the speed to autonegotiates speed only, and setting duplex to autonegotiates duplex only. Table 1-1 describes the access server's performance 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.

The PA-12E/2FE Ethernet switch port adapter provides Cisco 7200 series routers with up to 12 10-Mbps and 2 10/100-Mbps switched Ethernet (10BaseT) and Fast Ethernet (100BaseTX) interfaces for an aggregate bandwidth of 435Mbps, 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 UTP cables.

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

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 (port0 and port1) 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-config command to determine if a PA-12E/2FE interface is autosensing and autonegotiating the proper transmission mode with an attached device. Use the full-duplex and the half-duplex commands to change the transmission mode of a PA-12E/2FE interface. After changing the transmission mode, use the show interfaces command to verify the interface's transmission mode.

To configure the PA-12E/2FE port adapter, perform the tasks in the following sections (the task in the first section is required; all other tasks are optional):

Configuring Bridge Groups by Using the 12E/2FE VLAN Configuration WebTool

The 12E/2FE VLAN Configuration WebTool, shown in Figure 1-1, is a Web browser-based Java applet that displays configured interfaces and bridge groups for PA-12E/2FE port adapters installed on Cisco routers. With the WebTool, you can perform the following tasks:

• Create and delete bridge groups (also referred to as VLANs)

• Add and remove PA-12E/2FE interfaces from bridge groups

• Assign colors to bridge groups and PA-12E/2FE interfaces

• Administratively shut down (disable) and bring up (enable) PA-12E/2FE interfaces

• View the bridge-group status of each PA-12E/2FE interface

Figure 1-1. Sample Home Page for a Cisco 7200 Series Router (Cisco 7206 Shown)

You can access the 12E/2FE VLAN Configuration WebTool from your router's home page.

Note

You must use a Java-enabled Web browser to access the 12E/2FE VLAN Configuration WebTool from your router's home page.

All Cisco routers running Cisco IOS Release 11.0 or later have a home page. If your router has an installed PA-12E/2FE port adapter, you can access the 12E/2FE VLAN Configuration WebTool from the router's home page.

Note

All Cisco router home pages are password protected. Contact your network administrator if you do not have the name or password for your Cisco 7200 series router.

Note

The VLAN Configuration WebTool hypertext link is listed in the router's home page only when a PA-12E/2FE port adapter is installed in the router.

The 100VG-AnyLAN port adapter (PA-100VG) is available on Cisco 7200 series routers and on Cisco 7500 series routers.

The PA-100VG provides a single interface compatible with and specified by IEEE 802.12 to support 100Mbps over Category 3 or Category 5 unshielded twisted-pair (UTP) cable with RJ-45 terminators. The PA-100VG supports 802.3 Ethernet packets and can be monitored with the IEEE802.12 Interface MIB.

To configure the PA-100VG port adapter, use the following commands beginning in global configuration mode:

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.

To configure the port-channel interface, use the following commands, beginning in global configuration mode:

To assign the Fast Ethernet interfaces to the Fast EtherChannel, use the following commands, beginning in global configuration mode:

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

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 (PAgP) in a subsequent release of this feature will remove the dependency on keepalives.

See the "LAN Interface Configuration Examples" section in this chapter for configuration examples.

You can monitor the status of the Fast 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:

Cisco FDDI by default 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:

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:

When you are doing translational bridging, you have to route routable protocols and use translational bridging for the rest (such as LAT).

Cisco is 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. Cisco recommends 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:

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:

The FDDI standard restricts the allowed time to be 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:

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 PCM state as defined by the X3T9.5 specification. To do so, use the following command in interface configuration mode:

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:

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:

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

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

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:

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

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 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:

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

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:

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

The FDDI interface is able to transmit multiple frames per token on Cisco 4000, Cisco 4500, and Cisco 4700 series routers instead of only a single frame at a time. You can specify the maximum number of frames to be transmitted with each token capture. This significantly improves your throughput when you have heavy or very bursty traffic.

To configure the FDDI interface to transmit a maximum number of frames per token capture, use the following commands:

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

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

To enable a hub port, use the following commands in global configuration mode:

On Ethernet hub ports only, the hub ports can invert, or correct, the polarity of the received data if the port detects that the received data packet waveform polarity is reversed due to a wiring error. This receive circuitry polarity correction allows the hub to repeat subsequent packets with correct polarity. When enabled, this function is executed once after reset of a link fail state.

Automatic receiver polarity reversal is enabled by default. To disable this feature on a per-port basis, use the following command in hub configuration mode:

To reenable automatic receiver polarity reversal on a per-port basis, use the following command in hub configuration mode:

The link test function applies to Ethernet hub ports only. The Ethernet ports implement the link test function as specified in the 802.3 10BaseT standard. The hub ports will transmit link test pulses to any attached twisted-pair device if the port has been inactive for more than 8 to 17 milliseconds.

If a hub port does not receive any data packets or link test pulses for more than 65 to 132milliseconds and the link test function is enabled for that port, that port will enter link fail state and be disabled from transmit and receive functions. The hub port will be reenabled when it receives four consecutive link test pulses or a data packet.

The link test function is enabled by default. To allow the hub to interoperate with 10BaseT twisted-pair networks that do not implement the link test function, the hub's link test receive function can be disabled on a per-port basis. To do so, use the following command in hub configuration mode:

To reenable the link test function on a hub port connected to an Ethernet interface, use the following command in hub configuration mode:

On an Ethernet hub port only, you can configure a security measure such that the port accepts packets only from a specific MAC address. For example, suppose your workstation is connected to port 3 on a hub, and source address control is enabled on port 3. Your workstation has access to the network because the hub accepts any packet from port 3 with your workstation's MAC address. Any packets arriving with a different MAC address cause the port to be disabled. The port is reenabled after 1minute and the MAC address of incoming packets is checked again.

To enable source address control on a per-port basis, use the following command in hub configuration mode:

If you omit the optional MAC address, the hub remembers the first MAC address it receives on the selected port and allows only packets from the learned MAC address.

See the examples of establishing source address control in the section, "Hub Configuration Examples."

To enable the router to issue an SNMP trap when an illegal MAC address is detected on an Ethernet hub port, use the following commands in hub configuration mode:

You may need to set up a host receiver for this trap type (snmp-server host) for a Network Management System to receive this trap type. The default is no trap. For an example of configuring an SNMP trap for an Ethernet hub port, see the section "Hub Configuration Examples."

Figure 1-3 is an expanded view of Figure 1-2 that shows all the components of the LAN Extender connection to a core router. On the left is the core router, which is connected to the LAN Extender as well as to other networks. In the core router, you configure a LAN Extender interface, which is a logical interface that connects the core router to the LAN Extender chassis. In the core router, you also configure a serial interface, which is the physical interface that connects the core router to the LAN Extender. You then bind, or associate, the LAN Extender interface to the physical serial interface.

Figure 1-3.  Expanded View of Cisco 1000 Series LAN Extender Connection

Figure 1-3 shows the actual physical connection between the core router and the LAN Extender. The serial interface on the core router is connected by a leased serial line to a serial port on the LAN Extender. This creates a virtual Ethernet connection, which is analogous to having inserted an Ethernet interface processor into the core router.

Although there is a physical connection between the core router and the LAN Extender, what you actually manage is a remote Ethernet LAN. Figure 1-4 shows the connection you are managing, which is a LAN Extender interface connected to an Ethernet network. The virtual Ethernet connection (the serial interface and LAN Extender) has been removed from the figure, and Points A and B, which in Figure 1-3 were separated by the virtual Ethernet connection, are now adjacent. All LAN Extender interface configuration tasks described in this chapter apply to the interface configuration shown in Figure 1-4.

Figure 1-4. LAN Extender Interface Connected to an Ethernet Network

To configure and create a LAN Extender interface, you configure the LAN Extender interface itself and the serial interface to which the LAN Extender is physically connected. The order in which you configure these two interface interfaces does not matter. However, you must first configure both interfaces in order for the LAN Extender interface to bind (associate) to the serial interface.

To create and configure a LAN Extender interface, use the following commands starting in interface configuration mode:

Note that there is no correlation between the number of the serial interface and the number of the LAN Extender interface. These interfaces can have the same or different numbers.

You can configure specific administrative filters that filter frames based on their source MAC address. The LAN Extender forwards packets between a remote LAN and a core router. It examines frames and transmits them through the internetwork according to the destination address, and it does not forward a frame back to its originating network segment.

You define filters on the LAN Extender interface in order to control which packets from the remote Ethernet LAN are permitted to pass to the core router (see Figure 1-6). These filters are applied only on traffic passing from the remote LAN to the core router. Filtering on the LAN Extender interface is actually performed in the LAN Extender, not on the core router. This means that the filtering is done using the LAN Extender CPU, thus off-loading the function from the core router. This process also saves bandwidth on the WAN, because only the desired packets are forwarded from the LAN Extender to the core router. Whenever possible, you should perform packet filtering on the LAN Extender.

Figure 1-6.  Packet Filtering on the LAN Extender

You can also define filters on the core router to control which packets from the LAN Extender interface are permitted to pass to other interfaces on the core router (see Figure 1-7). You do this using the standard filters available on the router. This means that all packets are sent across the WAN before being filtered and that the filtering is done using the core router's CPU.

Figure 1-7.  Packet Filtering on the Core Router

The major reason to create access lists on a LAN Extender interface is to prevent traffic that is local to the remote Ethernet LAN from traversing the WAN and reaching the core router. You can filter packets by MAC address, including vendor code, and by Ethernet type code. To define filters on the LAN Extender interface, perform the tasks described in one or both of the following sections:

When defining access lists, keep the following points in mind:

Priority output queuing is an optimization mechanism that allows you to set priorities on the type of traffic passing through the network. Packets are classified according to various criteria, including protocol and subprotocol type. Packets are then queued on one of four output queues.

To control priority queuing on a LAN Extender interface, perform the following tasks:

To establish queuing priorities based on the protocol type, use one of the following commands in global configuration mode:

You then assign a priority list to an interface. You can assign only one list per interface. To assign a priority list to a LAN Extender interface, use the following command in interface configuration mode:

Each time the core router sends a command to the LAN Extender, the LAN Extender responds with an acknowledgment. The core router waits for the acknowledgment for a predetermined amount of time. If it does not receive an acknowledgment in this time period, the core router resends the command.

By default, the core router waits 2 seconds for an acknowledgment from the LAN Extender. You might want to change this interval if your connection to the LAN Extender requires a different amount of time. To determine whether commands to the LAN Extender are timing out, use the debug lex rcmd privileged EXEC command. To change this interval, use the following command in interface configuration mode:

By default, the core router sends each command 10 times before giving up. The core router displays an error message when it gives up sending commands to the LAN Extender. To change this default, use the following command in interface configuration mode:

From the core router, you can shut down the LAN Extender's Ethernet interface. This stops traffic on the remote Ethernet LAN from reaching the core router, but leaves the LAN Extender interface that you created intact.

To shut down the LAN Extender's Ethernet interface, use the following command in interface configuration mode:

To restart the LAN Extender's Ethernet interface, use the following command in interface configuration mode:

To reboot the LAN Extender and reload the software, use one of the following commands in privileged EXEC mode:

When the LAN Extender is powered on, it runs the software image that is shipped with the unit. You can download a new software image from Flash memory on the core router or from a TFTP server or from Flash memory on the core router to the LAN Extender.

To download a software image to the LAN Extender, use one of the following commands in privileged EXEC mode:

The primary means of troubleshooting the LAN Extender is by using the light emitting diodes (LEDs) that are present on the chassis. This section will help you assist the remote user at the LAN Extender site who can observe the LEDs.

The key to problem solving is to try to isolate the problem to a specific subsystem. By comparing what the system is doing to what it should be doing, the task of isolating a problem is greatly simplified.

The Cisco 1000 series LAN Extender uses multiple LEDs to indicate its current operating condition. By observing the LEDs, any fault conditions that the unit is encountering can be observed. The system LEDs are located on the front panel of your LAN Extender (see Figure 1-8).

Figure 1-8.  LAN Extender LEDs

When there is a problem with the LAN Extender, a user at the remote site should contact you and report the condition of the LEDs located on the front panel of the LAN Extender. You can then use this information to diagnose or verify the operation of the system. Table 1-2 explains the LEDs.

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

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:

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:

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

To monitor the Token Ring Concentrator Port, use one or more of the following commands in EXEC mode: