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Use the information in this chapter to understand the types of interfaces supported on our routers. Our routers support two types of interfaces: physical and virtual interfaces. The physical types of interfaces you have depend on the appliques or interface processors you have. The virtual interfaces our routers support include subinterfaces and IP tunnels.
Our routers support the following types of interfaces:
In addition to the interface types, the router supports subinterfaces. See each protocol chapter for specific information on how to configure a subinterface for that protocol.
For hardware technical descriptions and information about installing the router interfaces, refer to the hardware installation and maintenance publication for your product. For command descriptions and usage information, refer to the "Interface Commands" chapter of the Router Products Command Reference publication. For a conversion table of the modular products and Cisco 7000 processors, refer to the "Cisco 7000 Processors" appendix in the Router Products Command Reference publication.
You can perform the tasks in the following sections to configure and maintain the interfaces supported on our routers:
Note For information about the Channel Interface Processor (CIP), see the chapter entitled "Configuring IBM Channel Attach." The CIP is described in a separate chapter because of the interrelation of host system configuration values and router configuration values.
See the end of this chapter for "Interface Configuration Examples."
Begin interface configuration in global configuration mode. To configure an interface, follow these steps:
Step 2 Once in the global configuration mode, start configuring the interface by entering the interface command. Identify the interface type followed by the number of the connector or interface card. These numbers are assigned at the factory at the time of installation or when added to a system and can be displayed with the show interfaces EXEC command. A report is provided for each interface the router supports, as seen in the following partial sample display:
Use the show hardware EXEC command to see a list of the system software and hardware.
For example, to begin configuring serial interface 0, you would add the following line to the configuration file:
Note It is not necessary to add a space between the interface type and interface number. For example, in the preceding line you can specify either serial 0 or serial0.
Step 3 Follow each interface command with the interface configuration commands your particular interface requires. These command define the protocols and applications that will run on this 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 type the Ctrl-Z sequence to get out of configuration mode and return to privileged EXEC mode.
Step 4 Once an interface is configured, you can check its status by entering the EXEC show commands described after the task tables that follow.
Note When you configure channelized T1, you must first define the channels and the timeslots that comprise the channels by using the controller t1 and the channel-group controller configuration commands. Then configure the virtual serial interfaces using the interface serial global configuration commands. See the section "Configure Channelized T1" later in this chapter for T1 configuration tasks.
The following sections show how to configure each interface type. Follow the interface command with the routing or bridging interface configuration commands for your particular protocol or application, as described in this chapter and subsequent chapters.
See the section "Examples of Enabling Interface Configuration" at the end of this chapter.
All of our router platforms configured with an auxiliary port support the asynchronous serial interface. To configure an asynchronous serial interface on the router, you must establish asynchronous serial line connections using PPP or SLIP. PPP and SLIP define methods of sending Internet packets over a standard RS-232 asynchronous serial line. PPP also defines methods for sending IPX packets.
To use the asynchronous device as a network interface via PPP or SLIP, complete the tasks in the following sections:
Note You can also configure support for SLIP and PPP using extended BOOTP requests. See the chapter entitled "Loading System Images, Microcode Images, and Configuration Files."
Only the auxiliary port on a router can be configured as an asynchronous serial interface. To configure an asynchronous serial interface on the router, you must establish asynchronous serial line connections using PPP or SLIP, as described in the next section.
The auxiliary port's absolute line number is 1. When you configure an asynchronous serial interface with the interface async 1 command, you enable asynchronous routing over the auxiliary port to support PPP and SLIP connections to remote routers. The interface number is the same as the absolute line number.
The router automatically associates the interface number 1 with the absolute line number 1 of the auxiliary port, and treats the interface as an asynchronous line. However, to configure the auxiliary port as an asynchronous interface, you must also configure it as an auxiliary line with the line aux 1 command as described in the chapter entitled "Configuring Terminal Lines and Modem Support." Follow the line command with the appropriate line configuration commands for modem control, such as speed. Perform the following task in global configuration mode to specify the auxiliary port line as an asynchronous interface:
Only IP packets can be sent across lines configured for SLIP. PPP supports transmission of both IP and IPX packets.
There are two asynchronous serial encapsulation methods:
SLIP and PPP are methods of encapsulating datagrams and other network-layer protocol information over point-to-point links. SLIP is the default method. Perform the following task in interface configuration mode to configure PPP or SLIP encapsulation on the asynchronous interface:
The configured SLIP or PPP encapsulation method applies to an interface configured for dedicated asynchronous mode or dial-on-demand routing (DDR). On an asynchronous interface configured for interactive mode, the encapsulation type is specified by the user with the slip or ppp EXEC command. See the "Configure Dedicated or Interactive Mode" section later in this section.
In order to use SLIP or PPP, the router must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style slip address commands. However, you must configure it manually if you configure SLIP or PPP via the interface async command.
See the section "Configure PPP" in the section "Configure a Synchronous Serial Interface" later in this chapter for more information about PPP.
You can control whether a user must specify an address when making a SLIP or PPP connection or whether the address is forced by the system. Using an address defined by the system is referred to as default addressing. Requiring the user to specify an address is called dynamic addressing. It is common to configure an asynchronous interface both to have a default address and to allow dynamic addressing.
This section describes how to do the following:
You can assign a permanent default asynchronous address to a line by performing the following task in interface configuration mode:
| Task | Command |
|---|---|
Use the no form of this command to disable the default address.
The assigned default address is used when the user enters the slip default or ppp default EXEC command. The TACACS server validates the transaction (when enabled), and the line is put into network mode using the address that is in the configuration file. This feature is useful when the user is not required to know the IP address to gain access to a system; for example, users of a server that is available to many students on a campus.
When a line is configured for dynamic assignment of asynchronous addresses, the user enters the slip or ppp EXEC command and is prompted for an address or logical host name. The TACACS validates the address, when enabled, and the line is assigned the given address and put into asynchronous mode. Assigning asynchronous addresses dynamically is also useful when you want to assign set addresses to users. For example, an application on a personal computer that automatically dials in using SLIP and polls for electronic mail messages can be set up to dial in periodically and enter the required IP address and password.
To configure asynchronous dynamic addressing, perform the following task in interface configuration mode:
The dynamic addressing features of the internetwork allow packets to get to their destinations and back regardless of the router or network they are sent from. For example, if a host such as a laptop computer moves from place to place, it can keep the same address no matter where it is dialing in from. For an example of configuring asynchronous dynamic addressing, see the section "Example of Asynchronous Routing and Dynamic Addressing" at the end of this chapter.
The Dynamic Host Configuration Protocol (DHCP) model consists of the following components:
The DHCP client-proxy feature manages a pool of IP addresses available to PPP or SLIP dial-in clients without a known IP address. This pool allows a finite number of IP addresses to be reused quickly and efficiently by many clients. Additional benefits include the ability to maintain sessions, such as Telnet, even when a modem line fails. When the client is auto-dialed back into the server, the session can be resumed because the same IP address is reissued to the client by the server.
You can designate all of the router's asynchronous interfaces to use DHCP or can turn off DHCP on individual interfaces. Cisco's implementation of DHCP complies with RFC 1541, and is compliant with extended TACACS.
To enable DHCP on a router's asynchronous interfaces, perform the following tasks, starting in global configuration mode:
You can configure the asynchronous interface to be in dedicated network or interactive mode.
In dedicated mode, there is no user prompt or EXEC level, so no end-user commands are required to place the line into interface mode. When the interface is configured for dedicated mode, the user cannot change the encapsulation method, address, or other parameters.
To configure an asynchronous interface to be in dedicated network mode, perform the following task in interface configuration mode:
For an example of placing an asynchronous interface into dedicated network mode, see the section "Example of a Dedicated Asynchronous Interface" at the end of this chapter.
Alternatively, you can configure an asynchronous line for interactive mode. In interactive mode, the line can be used to make any type of connection, depending on the EXEC command entered by the user. For example, depending on its configuration, the line could be used for Telnet connections, or SLIP or PPP encapsulation. Perform the following task in interface configuration mode to configure an asynchronous line for interactive mode:
You can enable use of dynamic routing protocols on the asynchronous interface by performing the following task in interface configuration mode:
You can use an asynchronous device as a network interface connection to a remote router via the auxiliary port using the PPP or SLIP protocols. Refer to the Cisco Access Connection Guide.
See the "Configuring ATM" chapter for information on how to configure an Asynchronous Transfer Mode (ATM) interface.
See also the section "Invoke ATM over a Serial Line" in the section "Configure a Synchronous Serial Interface" later in this chapter.
Support for channelized E1 is provided on the following platforms:
Each E1 adapter can support a maximum of 30 channel groups. The Cisco 7000 MIP can support one or two adapters, providing a maximum of 60 channel groups per MIP. The Cisco 4000 can support one adapter, providing a maximum of 30 channel groups. Each channel group is presented to the system as a serial interface that can be configured individually. In effect, up to 30 E1 circuits are multiplexed to each hardware adapter.
Use the show controllers e1 EXEC command to display current E1 status. This command provides a report for each physical interface configured to support channelized E1.
Channelized E1 supports the following WAN protocols:
When a channelized E1 adapter is used for ISDN PRI, it can support DDR; when it is not used for ISDN PRI, it does not support DDR. Refer to the "Configuring ISDN" chapter of this manual for more information.
Using channelized E1 controller and serial interface configuration commands, you can perform the tasks in the following sections to configure channelized E1:
See the end of this chapter for "Interface Configuration Examples."
To configure the E1 physical characteristics, you first define the location of the controller in the router. A Cisco 7000 router can have up to four MIP and eight CX-MIP-CE1 interfaces. A Cisco 7010 router can have up to three MIP and six CX-MIP-CE1 interfaces. The Cisco 4000 series routers can support up to three network processor module (NPM) cards, each with one interface when running it as a channelized interface card. However, when the card is used to run ISDN PRI, only one NPM can be used in the Cisco 4000 and two NPMs can be used in the Cisco 4500.
Note You can define ISDN PRI groups and channel groups on the same controller. However, you cannot overlap timeslots or use the ISDN D-channel timeslot in a channel group.
Perform the following task in global configuration mode to define the E1 controller and to enter controller configuration mode:
| Task | Command |
|---|---|
Define the controller location in the Cisco 7000 series by slot and port number. Define the controller location in the Cisco 4000 series by unit number, ranging from 0 through 2. |
Perform the following task in controller configuration mode to define the line code as either alternate mark inversion (AMI) or HDB3:
Contact your local telephone service provider to determine the line-code requirements of the physical E1 line. The E1 controller values must match the service provided by the telephone company.
Perform the following task in controller configuration mode to define the framing characteristics as either CRC4 or no-CRC4, or as the version of E1 framing used in Australia only:
Contact your local telephone service provider to determine the framing requirements of the physical E1 line. The E1 controller values must match the service provided by the telephone company.
You can define up to 30 channel groups for each E1 adapter. You must define the timeslots that belong with each channel group. Channel groups are numbered 0 to 30, and timeslots are numbered 1 to 31. Perform the following task in controller configuration mode to define the channel groups and timeslots:
Working with your local service provider, you can create channel-groups with from one to 31 timeslots. These timeslots can be in any order, contiguous or noncontiguous. Channel-group speeds can be 48 kbps, 56 kbps, or 64 kbps; the default is 64 kbps if the speed is not specified. The speed you choose must match the speed specified by your service provider. 7
Defining a channel group creates a serial interface; defining multiple channel groups creates an equal number of serial interfaces that you can configure independently. The channel group numbers for each E1 controller can be arbitrarily assigned.
After you define the E1 channel groups, you can configure each channel group as a serial interface. In other words, you can think of each channel group as a virtual serial interface. Subinterface configuration on the created interface is also supported. Perform the following task either in global configuration mode or controller configuration mode to enter interface configuration mode and configure the serial interface that corresponds to a channel group:
E1 channel groups support local loopback. You can enable local loopback for specified individual channel groups with the loopback local command. Local loopback loops the entire specified channel group both toward the line and toward the router.
E1 channel groups do not respond to any remote loopback codes. That is, you cannot remotely loop an E1 channel group.
Support for channelized T1 (also referred to as fractional T1) is provided on the following platforms:
Each T1 adapter can support a maximum of 24 DS0 channel groups. Each channel group is presented to the system as a serial interface that can be configured individually. The Cisco 7000 MIP can support one or two CxCT1 adapters, providing a maximum of 48 channel groups per MIP. The Cisco 4000 supports a one adapter, providing a maximum of 24 channel groups. In effect, up to 24 DS0 circuits are multiplexed to a single hardware adapter.
Use the show controllers t1 EXEC command to display current T1 status. This command provides a report for each physical interface configured to support channelized T1.
Channelized T1 supports the following WAN protocols:
When a channelized T1 adapter is used for ISDN PRI, it can support DDR; when it is not used for ISDN PRI, it does not support DDR. Refer to the "Configuring ISDN" chapter of this manual for more information.
The Cisco channelized T1 controllers require the use of a CSU when connected to a public network. This device should take a T1 signal from the public network and provide a T1 signal to the channelized T1 controller.
Using channelized T1 controller and serial interface configuration commands, you can perform the tasks in the following sections to configure channelized T1:
See the end of this chapter for "Interface Configuration Examples."
To configure the T1 physical characteristics, you first define the physical location of the MIP and CxCT1 in the Cisco 7000 series router. A Cisco 7000 router can have up to four MIP and eight CxCT1 interfaces. A Cisco 7010 router can have up to three MIP and six CxCT1 interfaces. The Cisco 4000 series routers can support up to three network processor module (NPM) cards, each with one interface when running it as a channelized interface card. However, when the card is used to run ISDN PRI, only one NPM can be used in the Cisco 4000 and two NPMs can be used in the Cisco 4500.
Note You can define ISDN PRI groups and channel groups on the same controller. However, you cannot overlap timeslots or use the ISDN D-channel timeslot in a channel group.
Perform the following task in global configuration mode to define the T1 controller and to enter controller configuration mode:
| Task | Command |
|---|---|
Define the MIP and CxCT1 locations in the Cisco 7000 series by slot and port number. Define the controller location in the Cisco 4000 series by unit number, ranging from 0 through 2. |
Perform the following task in controller configuration mode to define the line code as either alternate mark inversion (AMI) or bipolar 8 zero substitution (B8ZS):
Contact your local telephone service provider to determine the line-code requirements of the physical T1 line. The T1 controller values must match the service provided by the telephone company.
Perform the following task in controller configuration mode to define the framing characteristics as either super frame (SF) or extended super frame (ESF):
Contact your local telephone service provider to determine the framing requirements of the physical T1 line. The T1 controller values must match the service provided by the telephone company.
Under normal usage, skip this step. You must define the clock source only when connecting two devices back-to-back for testing purposes. The clock source normally comes from the T1 line rather than from the router interface, but when you connect two routers back-to-back for testing purposes, one device supplies an internal clock source. To define the clock source, perform the following task in controller configuration mode:
| Task | Command |
|---|---|
Define the clock source if you are connecting two cards back-to-back for testing purposes; the default source is the line. |
You can define up to 24 channel groups for each T1 adapter.You must define the timeslots that belong with each channel group. Channel groups are numbered 0 to 23, and timeslots are numbered 1 to 24. Perform the following task in controller configuration mode to define the channel groups and timeslots:
Working with your local service provider, you can create channel-groups with from one to 24 timeslots. These timeslots can be in any order, contiguous or noncontiguous. In the United States, channel-group speeds can be either 56 kbps or 64 kbps; the default is 56 kbps. If 64 kbps is used, it is recommended to be used with framing type of ESF and a linecode of B8ZS. The speed you select must match the speed provided by the telephone company.
Defining a channel group creates a serial interface; defining multiple channel groups creates an equal number of serial interfaces that you can configure independently. The channel group numbers for each T1 controller can be arbitrarily assigned.
After you define the T1 channel groups, you can configure each channel group as a serial interface. In other words, you can think of each channel group as a virtual serial interface. Subinterface configuration is also supported on the created serial interface. Perform the following task either in global configuration mode or controller configuration mode to enter interface configuration mode and configure the serial interface that corresponds to a channel group:
See the chapter "Configuring DDR" for information about how to configure a dialer interface.
Support for the Ethernet interface is supplied on one of the following Ethernet network interface cards or systems:
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.
Use the show interfaces fastethernet command to display the Fast Ethernet slots and ports. The FEIP defaults to half-duplex mode and media type 10BaseTX.
The Fast Ethernet encapsulation methods are the same as the Ethernet encapsulation methods. See the section "Etherenet Encapsulation Methods."
Perform the tasks in the following sections to configure features on an Ethernet interface. The first task is required; the remaining tasks are optional.
To specify an Ethernet interface and enter interface configuration mode, perform one of the following tasks in global configuration mode:
| Task | Command |
|---|---|
Currently, there are three common Ethernet encapsulation methods:
The encapsulation method you use depends upon the type of Ethernet media connected to the router and the routing or bridging application you configure. Establish Ethernet encapsulation by performing one of the following tasks in interface configuration mode:
| Task | Command |
|---|---|
For an example of selecting Ethernet encapsulation, see the section "Example of Enabling Ethernet Encapsulation" at the end of this chapter. See also the chapters describing specific protocols or applications.
You can specify the type of Ethernet Network Interface Module configuration on the Cisco 4000. To do so, perform one of the following tasks in interface configuration mode:
| Task | Command |
|---|---|
On a Cisco 4000 or Cisco 4500, 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, perform the first task that follows in interface configuration mode. You can later restore the squelch by performing the second task.
The Fiber Distributed Data Interface (FDDI) is an ANSI-defined standard for timed 100-Mbps token passing over fiber-optic cable. An FDDI network consists of two counter token-passing fiber-optic rings. On most networks, the primary ring is used for data communication and the secondary ring is used as a hot standby. The FDDI standard sets a total fiber length of 200 kilometers. (The maximum circumference of the FDDI network is only half the specified kilometers because of the wrapping or looping back of the signal that occurs during fault isolation.)
The FDDI standard allows a maximum of 500 stations with a maximum distance between active stations of two kilometers when interconnecting them with multimode fiber or ten kilometers when interconnected via single mode fiber, both of which are supported by our FDDI interface controllers. The FDDI frame can contain a minimum of 17 bytes and a maximum of 4500 bytes. Our implementation of FDDI supports Station Management (SMT) Version 7.3 of the X3T9.5 FDDI specification, offering a single MAC dual-attach interface that supports the fault-recovery methods of the dual attachment stations (DASs). The mid-range platforms also support single attachment stations (SASs).
Support for FDDI is supplied on one of our FDDI interface cards, as follows:
We also provide support for some of the FDDI MIB variables as described in RFC 1285, "FDDI Management Information Base," published in January 1992 by Jeffrey D. Case of the University of Tennessee and SNMP Research, Inc. One such variable that we support is snmpFddiSMTCFState.
FDDI interface configuration is not required for dual homing. The FDDI interface recognizes that it is attached to two M ports on the concentrators and automatically supports dual homing.
Connection Management (CMT) is an FDDI process that handles the transition of the ring through its various states (off, on, active, connect, and so on) as defined by the X3T9.5 specification. The FIP provides CMT functions in microcode.
A partial sample output of the show interfaces fddi command follows, along with an explanation of how to interpret the CMT information in the output.
The show interfaces fddi example shows that Physical A (Phy-A) completed CMT with its neighbor. The state is active and the display indicates a Physical B-type neighbor.
The sample output indicates cmt signal bits 08/20C for Phy-A. The transmit signal bits are 08. Looking at the PCM state machine, 08 indicates that the port type is A, the port compatibility is set, and the LCT duration requested is short. The receive signal bits are 20C, which indicate the neighbor type is B, port compatibility is set, there is a MAC on the port output, and so on.
The neighbor is determined from the received signal bits, as follows:
Interpreting the bits in the diagram above, the received value equals 0x20C. Bit positions 1 and 2 (0 1) indicate a Physical B-type connection.
The transition states displayed indicate that the CMT process is running and actively trying to establish a connection to the remote physical connection. The CMT process requires state transition with different signals being transmitted and received before moving on to the state ahead as indicated in the PCM state machine. The ten bits of CMT information are transmitted and received in the Signal State. The NEXT state is used to separate the signaling performed in the Signal State. Therefore, in the preceding sample output, the NEXT state was entered 11 times.
Note The display line showing transition states is not generated if the FDDI interface has been shut down, or if the cmt disconnect command has been issued, or if the fddi if-cmt command has been issued. (The fddi if-cmt command applies to the AGS+ and Cisco 7000 only.)
The CFM state is thru A in the sample output, which means this interface's Phy-A has successfully completed CMT with the Phy-B of the neighbor and Phy-B of this interface has successfully completed CMT with the Phy-A of the neighbor.
The display (or nondisplay) of the upstream and downstream neighbor does not affect the ability to route data. Since the upstream neighbor is also its downstream neighbor in the sample, there are only two stations in the ring: the network server and the router at address 0800.2008.C52E.
Perform the tasks in the following sections to configure an FDDI interface. The first task is required; the remaining tasks are optional.
To specify an FDDI interface and enter interface configuration mode, perform one of the following tasks in global configuration mode:
| Task | Command |
|---|---|
Our 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 CSC-FCI interface card or FIP.
The CSC-C2/FCIT interface card and FIP fully support transparent and translational bridging for the following configurations:
Enabling FDDI bridging encapsulation places the CSC-C2/FCIT interface or FIP into encapsulation mode when doing bridging. In transparent mode, the FCIT interface or FIP interoperates with earlier versions of the CSC-FCI encapsulating interfaces when performing bridging functions on the same ring. When using the CSC-C2/FCIT interface card or FIP, you can specify the encapsulation method by performing the following task in interface configuration mode:
When you are translationally bridging, you have to route routable protocols and translationally bridge the rest (such as LAT).
The CSC-FCI interfaces are always in encapsulating bridge mode, so disabling applies only to CSC-C2/FCIT interfaces.
Note Bridging between dissimilar media presents several problems that can prevent communications. These problems include bit-order translation (or use of 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 when bridging between Token Rings and Ethernets or between Token Rings and FDDI nets. This is because of the different way 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.
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, perform the following task 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 performing the following task 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 Physical Connection Management or PCM state as defined by the X3T9.5 specification. To do so, perform the following task in interface configuration mode:
You can modify the C-Min timer on the PCM from its default value of 1600 microseconds by performing the following task in interface configuration mode:
You can change the TB-Min timer in the PCM from its default value of 100 milliseconds. To do so, perform the following task in interface configuration mode:
You can change the FDDI timeout timer in the PCM from its default value of 100 milliseconds. To do so, perform the following task in interface configuration mode:
You can disable and reenable SMT frame processing for diagnostic purposes. To do so, perform one of the following tasks in interface configuration mode:
| Task | Command |
|---|---|
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, perform the following task in interface configuration mode:
You can set the FDDI bit control to control the information transmitted during the Connection Management (CMT) signaling phase. To do so, perform the following task in interface configuration mode:
You can control whether the CMT onboard functions are on or off. The CSC-FCI and CSC-C2/FCIT interface cards and FIP provide 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 FCIT and 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, perform the following task 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, perform either of the following tasks in EXEC mode:
| Task | Command |
|---|---|
Do not do either of the preceding tasks during normal operation of FDDI; they are performed during interoperability tests.
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 you are configuring gets bursts of messages arriving faster than the router can process them. To set the number of frames, perform the following task 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 performing the following task in interface configuration mode:
The High-Speed Serial Interface (HSSI) consists of the following components:
The controller card provides a single, full-duplex, synchronous serial interface capable of transmitting and receiving data at up to 52 megabits per second (Mbps). The HSSI is an approved standard (ANSI/EIA RS-613) providing connectivity to T3 (DS-3), E3, SMDS (at a DS-3 route), and other high-speed wide-area services through a DSU or line termination unit.
Perform the tasks in the following sections to configure an HSSI interface. The first task is required; the remaining tasks are optional.
To specify an HSSI and enter interface configuration mode, perform one of the following tasks in global configuration mode:
| Task | Command |
|---|---|
The HSSI supports the serial encapsulation methods, except for X.25-based encapsulations. The default method is HDLC. You can define the encapsulation method by performing the following task in interface configuration mode:
| Task | Command |
|---|---|
encapsulation {atm-dxi | hdlc | frame-relay | ppp | sdlc-primary | sdlc-secondary | smds | stun} |
For information about PPP, see the section "Configure PPP" in the section "Configure a Synchronous Serial Interface" later in this chapter.
If you have an ATM DSU, you can invoke ATM over a HSSI line.You do so by mapping an ATM virtual path identifier (VPI) and virtual channel identifier (VCI) to a DXI frame address. ATM-DXI encapsulation defines a data exchange interface that allows a DTE (such as a router) and a DCE (such as an ATM DSU) to cooperate to provide a User - Network Interface (UNI) for ATM networks.
To invoke ATM over a serial line, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Specify the encapsulation method. | |
| Step 2. Map a given VPI and VCI to a DXI frame address. |
You can also configure the atm-dxi map command on a serial interface.
To configure an ATM interface using an AIP card, see the chapter "Configuring ATM."
You can convert the HSSI interface into a 45-MHz clock master by performing the following task in interface configuration mode:
The Cisco 2500 series includes routers that have hub functionality for an Ethernet interface. The hub is a multiport repeater. The advantage of an Ethernet interface over a hub is that the hub provides a star-wiring physical network configuration while the Ethernet interface provides 10BaseT physical network configuration. The router models with hub ports and their configurations are as follows:
We provide SNMP management of the Ethernet hub as specified in RFC 1516.
To configure hub functionality on an Ethernet interface, perform the tasks in the following sections. The first task is required; the remaining are optional.
See the end of this chapter for "Examples of Hub Configuration."
To enable a hub port, perform the following tasks in global configuration mode:
| Task | Command |
|---|---|
| Step 1. Specify the hub number and the hub port (or range of hub ports) and enter hub configuration mode. | |
| Step 2. Enable the hub ports. |