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Configuring LAN Interfaces
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From:
Cisco IOS 12.0 Interface Configuration
Author: Technologies Riva; Systems Cisco
Publisher: Cisco Press (53)
More Information
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You can use the information in this
chapter to configure LAN interfaces supported on Cisco routers and access
servers. This chapter describes the processes for configuring LAN interfaces.
It contains these sections: For examples of configuration tasks, see the section “LAN Interface
Configuration Examples” at the end of this chapter.
For hardware technical descriptions and information about installing interfaces,
refer to the hardware installation and configuration publication for your
product. For a complete description of the LAN interface commands
used in this chapter, see Chapter 4, “Configuring
Interface Commands.” To locate documentation of other commands
that appear in this chapter, search online at www.cisco.com.
Cisco supports both 10-Mbps Ethernet and 100-Mbps
Fast Ethernet. Support for the 10-Mbps and 100-Mbps Ethernet interface is
supplied on various Ethernet network interface cards or systems. The Fast
Ethernet NP-1FE module, for example, provides the following benefits: -
VLAN routing—VLAN
support enables network managers to group users logically rather than
by physical location. The high performance of the underlying Cisco 4700,
combined with the feature-rich NP-1FE, makes it an ideal combination
for a low-density, higher-performance application such as inter-VLAN
routing.
-
High-speed interconnections—The
Fast Ethernet interface enables network managers to implement Fast Ethernet
routing solutions for optimal cost and performance across a wide range
of applications, including campus or enterprise backbones and data centers.
It is also a low-cost way to provide Fast Ethernet access to traditional
low-speed WAN services.
-
Local-area network (LAN) aggregation— The Cisco 4500 series
or Cisco 4700 series routers can support as many as 12Ethernet, 4 Token
Ring, or 1 FDDI segment. ISDN interfaces are also supported.
With the Catalyst 3000 or Catalyst 5000 system, the Fast Ethernet processor
can be used to aggregate up to twelve 10-Mbps LANs and give them high-speed
access to such Layer 3 routing services as providing firewalls and maintaining
access lists.
Cisco 7200 series routers support a new I/O controller with an RJ-45 interface.
The optional Fast Ethernet port is configurable for use at 100-Mbps full-duplex
or half-duplex operation (half duplex is the default). The
Fast Ethernet port is equipped with either a single MII receptacle or an
MII receptacle and an RJ-45 receptacle. To support this new feature, the
media-type
interface command has been modified. The media-type interface command
now supports two options:
Second-generation Fast Ethernet Interface Processors (FEIP2-DSW-2TX
and FEIP2-DSW-2FX) are available on Cisco 7500 series routers and on Cisco7000
series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000
Series Chassis Interface (RSP7000CI). The FEIP2-DSW is a dual-port, fixed-configuration
interface processor that provides two 100-Mbps Fast Ethernet (FE) interfaces.
Each interface on the FEIP2-DSW supports half-duplex only for a maximum aggregate
bandwidth of 200Mbps.
Use the show
interfaces, show controllers mci, and show
controllers cbus EXEC commands to display the Ethernet port numbers.
These commands provide a report for each interface supported by the router
or access server.
Use the show interface fastethernet command
to display interface statistics, and use the show controller fastethernet
command
to display the information about the Fast Ethernet controller chip. The
output shows statistics that include information about initialization block
information, transmit ring, receive ring, and errors.
For information on how to configure Fast EtherChannel, refer to the
tasks listed in the “Configuring Fast EtherChannel” section in
this chapter. You perform the tasks in the following sections to configure features
on an Ethernet or Fast Ethernet interface (the task in the first section is
required; the remaining tasks are optional): 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 standard ARPA Ethernet Version 2.0 encapsulation, which
uses a 16-bit protocol type code (the default encapsulation method) SAP IEEE 802.3 encapsulation, in which the type code becomes
the frame length for the IEEE802.2 LLC encapsulation (destination and source
service access points, and a control byte) The SNAP method, as specified in RFC 1042, which allows Ethernet
protocols to run on IEEE802.2 media
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.
CAUTION
To prevent system problems, do not configure both FEIP2-DSW-2FX interfaces
for full-duplex operation at the same time. NOTE 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 Cisco4000 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: 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 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. NOTE This does not apply to the FastEthernet 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:
-
The auto option automatically negotiates the speed based
on the speed and the peer router, hub, or switch media.
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.
Table 1-1. The Relationship
Between Duplex and Speed Command Options
|
Duplex Command
|
Speed Command
|
Resulting System Actions
|
|---|
|
duplex auto
|
speed auto
| Autonegotiates both speed and duplex modes. | |
duplex auto
|
speed 100 or speed 10
| Autonegotiates both speed and duplex
modes. | |
duplex half or duplex full
|
speed auto
| Autonegotiates both
speed and duplex modes. | |
duplex half
|
speed 10
| Forces 10 Mbps
and half duplex. | |
duplex full
|
speed 10
| Forces 10 Mbps and full duplex. | |
duplex half
|
speed 100
| Forces 100 Mbps and half duplex. | |
duplex full
|
speed 100
| Forces 100 Mbps and full duplex. |
The PA-12E/2FE Ethernet switch port adapter provides Cisco7200 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 Layer2 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). 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 Cisco7200 series router. (Single-width port adapters occupy individual port
adapter slots in a Cisco7200 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
(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.
NOTE
If you use the full-duplex and the half-duplex commands
to change the transmission mode of the first two PA-12E/2FE interfaces
(port0 and port1), the transmission speed of the two PA-12E/2FE interfaces
automatically defaults to 100 Mbps. The first two PA-12E/2FE interfaces
only operate 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 (the task in the first section is required; all other tasks are optional): NOTE
If you plan to use a PA-12E/2FE interface to boot from a network
(TFTP), ensure that the interface is configured for a loop-free environment,
an IP address is configured for the interface's bridge-group virtual
interface, and system boot image 11.2(10)P is installed on your router
(use the show version command to view your router's system
boot image). 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
information on other commands that can be used to configure a PA-12E/2FE
port adapter, see Chapter 4, “Configuring
Interface Commands.” For PA-12E/2FE port adapter configuration
examples, see the “PA-12E/2FE Port Configuration Examples”
section later in this chapter.
This section provides
instructions for a basic configuration. You might also need to enter other
configuration commands, depending on the requirements for your system configuration
and the protocols you plan to route on the interface. To configure the interfaces on the PA-12E/2FE port adapter, use the
following commands in global configuration mode: To enable integrated routing and bridging on the bridge groups, use
the following commands beginning in global configuration mode: After configuring the new interface, you can display its status and verify other information.
To display information about the PA-12E/2FE port adapter, use the following
commands in EXEC mode:
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 Ciscorouters. 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
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 Cisco7200 series
router. 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 Cisco7500 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: 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.
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