Fast Serial Interface Processor (FSIP) Installation and Configuration

This completes the FSIP installation. If you installed a new FSIP or if you replaced a four-port FSIP with an eight-port FSIP, you must now configure the new interfaces as described in the following section.

Configuring the FSIP

If you installed a new FSIP, or replaced a four-port FSIP with an eight-port FSIP, or if you want to change the configuration of an existing interface, you must enter the configuration mode to configure the new interfaces. If you replaced an FSIP that was previously configured, the system will recognize the new FSIP interfaces and bring each of them up in their existing configuration.

After you verify that the new FSIP is installed correctly (the enabled LED goes on), use the privileged-level configure command to configure the new interfaces. Be prepared with the information you will need, such as the following:

• Protocols you plan to route on each new interface
  

• Internet protocol (IP) addresses if you will configure the interfaces for IP routing
  

• Whether or not the new interfaces will use bridging
  

• Timing source for each new interface and clock speeds for external timing
  

Refer to the appropriate software documentation for descriptions of the configuration options available and instructions for configuring a serial interface.

The following sections describe the commands for configuring an external clock signal for a DCE interface and for configuring a port for NRZI encoding or 32-bit CRC. Configuration commands are executed from the privileged level of the EXEC command interpreter, which usually requires password access. (See the section "Using the EXEC Command Interpreter" on page 35.) Refer to the description that follows and contact your system administrator, if necessary, to obtain access.

Configuring Timing (Clock) Signals

All interfaces support both DTE and DCE mode, depending on the mode of the interface cable attached to the port. To use a port as a DTE interface, you need only connect a DTE adapter cable to the port. When the system detects the DTE mode cable, it automatically uses the external timing signal. To use a port in DCE mode, you must connect a DCE interface cable and set the clock speed with the clockrate configuration command. You must also set the clock rate to perform a loopback test. This section describes how to set the clock rate on a DCE port and, if necessary, how to invert the clock to correct a phase shift between the data and clock signals.

Setting the Clock Rate

All DCE interfaces require a noninverted internal transmit clock signal, which is generated by the FSIP. The default operation on an FSIP DCE interface is for the DCE device (FSIP) to generate its own clock signal (TxC) and send it to the remote DTE. The remote DTE device returns the clock signal to the DCE (FSIP port). The clockrate command specifies the rate as a bits-per-second value. In the following example, the clock rate for the top serial interface on an FSIP in interface processor slot 3 (3/0) is defined as 72 kbps:

Router(config)# interface serial 3/0

Router(config-int)# clockrate 72000

Use the no clockrate command to remove the clock rate.

Following are the acceptable clockrate settings:

1200, 2400, 4800, 9600, 19200
38400 , 56000 , 64000 , 72000 , 125000
148000 , 500000, 800000, 1000000, 1300000
2000000 , 4000000 , 8000000

Speeds above 64 kbps (64000) are not appropriate for EIA/TIA-232. On all interface types, faster speeds might not work if your cable is too long.

Inverting the Clock Signal

Systems that use long cables may experience high error rates when operating at the higher transmission speeds. Slight variances in cable construction, temperature, and other factors can cause the clock and data signals to shift out of phase. If an FSIP DCE port is reporting a high number of error packets, a phase shift might be the problem. Inverting the clock can often correct this shift.

When a port is operating in DCE mode, the default operation is for the attached DTE device to return the clock signal (SCTE) to the DCE (SIP port). The DCE sends SCT and SCR clock signals to the DTE, and DTE returns an SCTE clock signal to the DCE. If the DTE device does not return SCTE, you must use the command transmit-clock-internal to configure the DCE port to use its own clock signal in place of the SCTE signal that would normally be returned from the DTE device.

To configure an interface to accept the internal clock generated by the FSIP in place of the SCTE clock that is normally returned by the DTE device, specify the slot and port address of the interface followed by the command transmit-clock-internal. In the example that follows, the first (top) serial port on a SIP in interface slot 3 is configured to accept the internal clock signal:

Router(config)# interface serial 3/0

Router(config-int)# transmit-clock-internal

To negate this command, use the no transmit-clock-internal command.

When the FSIP port is a DTE, the invert-transmit-clock command inverts the TxC signal it receives from the remote DCE. When the FSIP port is a DCE, this command inverts the clock signal to the remote DTE port. Use the no invert-transmit-clock command to change the clock signal back to its original phase.

Configuring NRZI Format

All interfaces support both NRZ and NRZI formats. Both formats use two different voltage levels for transmission. NRZ signals maintain constant voltage levels with no signal transitions (no return to a zero voltage level) during a bit interval and are decoded using absolute values (0 and 1). NRZI uses the same constant signal levels but interprets the presence of data at the beginning of a bit interval as a signal transition, and the absence of data as no transition. NRZI uses differential encoding to decode signals, rather than determining absolute values.

NRZ format, the factory default on all interfaces, is most common. NRZI format, which is configured with a software command, is commonly used with EIA/TIA-232 connections in IBM environments.

To enable NRZI encoding on any interface, specify the slot and port address of the interface followed by the command nrzi-encoding. Enter Ctrl-Z when you have finished with the configuration change. In the example that follows, the top serial port on an FSIP in interface processor slot 3 is configured for NRZI encoding:

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface serial 3/0
Router(config-int)# nrzi-encoding 
Router(config-int)# ^Z

To disable NRZI encoding on a port, specify the slot and port address and use the no nrzi-encoding command. For complete command descriptions and instructions, refer to the related software documentation.

Configuring CRCs

CRC is an error-checking technique that uses a calculated numeric value to detect errors in transmitted data. All interfaces use a 16-bit CRC by default, but also support a 32-bit CRC. The sender of a data frame divides the bits in the frame message by a predetermined number to calculate a remainder or frame check sequence (FCS). Before it sends the frame, the sender appends the FCS value to the message so that the frame contents are exactly divisible by the predetermined number. The receiver divides the frame contents by the same predetermined number that the sender used to calculate the FCS. If the result is not 0, the receiver assumes that a transmission error occurred and sends a request to the sender to resend the frame.

The designators 16 and 32 indicate the number of check digits per frame that are used to calculate the FCS. CRC-16, which transmits streams of 8-bit characters, generates a 16-bit FCS. CRC-32, which transmits streams of 16-bit characters, generates a 32-bit FCS. CRC-32 transmits longer streams at faster rates, and therefore provides better ongoing error correction with fewer retransmissions. Both the sender and the receiver must use the same setting.

The default for all serial interfaces is for 16-bit CRC. To enable 32-bit CRC on an interface, specify the slot and port address of the interface followed by the command crc32. In the example that follows, the top serial port on an FSIP in interface processor slot 3 is configured for 32-bit CRC:

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface serial 3/0
Router(config-int)# crc32 
Router(config-int)# ^Z

To disable CRC-32 and return to the default CRC-16 setting, specify the slot and port address and use the no crc32 command. For command descriptions, refer to the related software documentation.

Replacing Port Adapter Cables

The port adapter cable connected to each port determines the electrical interface type and mode of the port. The default mode of the ports is DCE, which allows you to perform a loopback test on any port without having to attach a port adapter cable. Although DCE is the default, there is no default clock rate set on the interfaces. When there is no cable attached to a port, the software actually identifies the port as Universal, Cable Unattached rather than either a DTE or DCE interface.

Following is an example of the show controller cxbus command that shows an interface port (2/0) that has an EIA/TIA-232 DTE cable attached, and a second port (2/1) that does not have a cable attached:

Router# show controller cxbus

Switch Processor 7, hardware version 11.1, microcode version 1.4
  512 Kbytes of main memory, 128 Kbytes cache memory, 299 1520 byte buffers
  Restarts: 0 line down, 0 hung output, 0 controller error
 FSIP 2, hardware version 3, microcode version 1.0
  Interface 16 - Serial2/0, electrical interface is RS-232 DTE
    31 buffer RX queue threshold, 101 buffer TX queue limit, buffer size 1520
    Transmitter delay is 0 microseconds
  Interface 17 - Serial2/1, electrical interface is Universal (cable unattached)
    31 buffer RX queue threshold, 101 buffer TX queue limit, buffer size 1520
    

To change the electrical interface type or mode of a port online, you replace the serial adapter cable and use software commands to restart the interface and, if necessary, reconfigure the port for the new interface. At system startup or restart, the FSIP polls the interfaces and determines the electrical interface type of each port (according to the type of port adapter cable attached). However, it does not necessarily repoll an interface when you change the adapter cable online. To ensure that the system recognizes the new interface type, shut down and reenable the interface after changing the cable.

Perform the following steps to change the mode or interface type of a port by replacing the adapter cable. First replace the cable, then shut down and bring up the interface with the new cable attached so that the system recognizes the new interface. If you are replacing a cable with one of the same interface type and mode, these steps are not necessary (simply replace the cable without interrupting operation).

Step 1 Locate and remove the adapter cable to be replaced.

Step 2 Connect the new cable between the FSIP port and the network connection. Tighten the thumbscrews at both ends of the cable to secure it in the ports.

Step 3 At the privileged level of the EXEC, specify the port address, shut down the interface, and write the configuration to nonvolatile random-access memory (NVRAM). Add additional configuration commands, if any, before you exit from the configuration mode (before you enter Ctrl-Z).

Router> enable

Password:

Router# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)# int serial 3/5

Router(config-int)# shutdown

Router(config-int)# ^Z

Router# write memory

Step 4 Enter the configuration mode again and bring the port back up.

Router# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)# int serial 3/5

Router(config-int)# no shutdown

Router(config-int)# ^Z

These steps will prompt the system to poll the interface and recognize new interface immediately.

When you configure a port for a DCE interface for the first time, or when you set up a loopback test, you must set the clock rate for the port. When you connect a DCE cable to a port, the interface will remain down, the clock LEDs will remain off, and the interface will not function until you set a clock rate (regardless of the DCE mode default).

If you are changing the mode of the interface from DCE to DTE, you do not need to change the clock rate for the port. After you replace the DCE cable with a DTE cable and the system recognizes the interface as a DTE, it will use the external clock signal from the remote DCE device and ignore the internal clock signal that the DCE interface normally uses. Therefore, once you configure the clock rate on a port for either a DCE interface or loopback, you can leave the clock rate configured and still use that port as a DTE interface.

Using the EXEC Command Interpreter

Before you use the configure command, you must enter the privileged level of the EXEC command interpreter with the enable command. The system will prompt you for a password if one has been set.

The system prompt for the privileged level ends with a pound sign (#) instead of an angle bracket (>). At the console terminal, enter the privileged level as follows:

Step 1 At the user-level EXEC prompt, enter the enable command. The EXEC prompts you for a privileged-level password, as follows:

Router> enable


Password:


Step 2 Enter the password (the password is case-sensitive). For security purposes, the password is not displayed.

Step 3 When you enter the correct password, the system displays the privileged-mode system prompt (#) as follows:

Router#

Proceed to the following section to configure the new interfaces.

Shutting Down an Interface

Before you remove an interface that you will not replace, or replace port adapters, shut down (disable) the interfaces to prevent anomalies when you reinstall the new or reconfigured interface processor. When you shut down an interface, it is designated administratively down in the show command displays.

Follow these steps to shut down an interface:

Step 1 Enter the privileged level of the EXEC command interpreter. (Refer to the previous section for instructions.)

Step 2 At the privileged-level prompt, enter the configuration mode and specify that the console terminal will be the source of the configuration subcommands, as follows:

Router# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#

Step 3 Specify the slot/port address of the first interface that you want shut down by entering the subcommand interface, followed by the type (serial) and slot/port (interface processor slot number/0). The example that follows is for an FSIP in interface processor slot 1:

Router(config)# interface serial 1/0

Step 4 Enter the shutdown command, as follows:

Router(config-int)# shutdown

Step 5 To shut down additional interfaces, enter the slot/port address of each additional interface followed by the shutdown command. When you have entered all the interfaces to be shut down, press Ctrl-Z (hold down the Control key while you press Z) to exit the configuration mode and return to the EXEC command interpreter prompt, as follows:

Router(config-int)# int serial 0/0

Router(config-int)# shutdown

Router(config-int)# int serial 2/0

Router(config-int)# shutdown

Router(config-int)# ^Z

Router#

Step 6 Write the new configuration to memory, as follows:

Router# copy running-config startup-config

[OK]

Router#

The system displays an OK message when the configuration has been stored.

Step 7 To verify that new interfaces are now in the correct state (shutdown), use the show interface serial slot/port command to display the specific interface, or use the show interfaces command, without variables, to display the status of all interfaces in the system.

Router# show int serial 1/0

Serial 1/0 is administratively down, line protocol is down

Hardware is cxBus FSIP

[display text omitted]

Step 8 To reenable the interfaces, repeat the previous steps, but use the no shutdown command in step 4, then write the new configuration to memory, as follows:

Router(config)# int serial 1/0

Router(config-int)# no shutdown

Router(config-int)# ^Z

Router# copy running-config startup-config

[OK]

Router# show int serial 1/0

Serial 1/0 is up, line protocol is up

Hardware is cxBus FSIP

[display text omitted]

For complete descriptions of software configuration commands, refer to the Router Products Configuration Guide publication.

Configuring Interfaces

Following are instructions for a basic configuration: enabling an interface, specifying IP routing, and setting up external timing on a DCE interface. You might also need to enter other configuration subcommands, depending on the requirements for your system configuration and the protocols you plan to route on the interface. For complete descriptions of configuration subcommands and the configuration options available for serial interfaces, refer to the appropriate software documentation.

Cisco 7000 series and Cisco 7500 series routers identify an interface address by its slot number and port number (port numbers 0 through 7, depending on the interface processor type) in the format slot/port. Each FSIP contains either four or eight serial interfaces. Ports are numbered sequentially beginning with either the top port (in the Cisco 7000, Cisco 7507, and Cisco 7513) or the left-most port (in the Cisco 7010, and the Cisco 7505), which is always port (interface) 0. For example, the slot/port address of the first interface on an FSIP installed in interface processor slot 1 is 1/0, and the adjacent port on the same FSIP is 1/1.

The following steps describe a basic configuration. Press the Return key after each step unless otherwise noted.

Step 1 At the privileged-level prompt, enter the configuration mode and specify that the console terminal will be the source of the configuration subcommands, as follows:

Router# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#

Step 2 At the prompt, specify the first interface to configure by entering the subcommand interface, followed by the type (serial) and slot/port (interface processor slot number/0). The example that follows is for the top port on an FSIP in interface processor slot 1:

Router(config)# interface serial 1/0

Step 3 If IP routing is enabled on the system, you can assign an IP address and subnet mask to the interface with the ip address configuration subcommand, as in the following example:

Router(config-int)# ip address 145.22.4.67 255.255.255.0

Step 4 Add any additional configuration subcommands required to enable routing protocols and adjust the interface characteristics.

Step 5 If you are configuring a DTE interface, proceed to step 7. If you are configuring a DCE interface, you also need to configure the external clock signal, as described in the next step.

Step 6 Set the clock rate with the clockrate command (see the section "Configuring Timing (Clock) Signals" on page 31).

Router(config-int)# clockrate 72000

Step 7 Change the shutdown state to up and enable the interface as follows:

Router(config-int)# no shutdown

Step 8 When you have included all of the configuration subcommands to complete the configuration, press Ctrl-Z to exit the configuration mode.

Step 9 Write the new configuration to memory as follows:

Router(config-int)# ^z

Router# copy running-config startup-config

[OK]

Router#

Step 10 Exit the privileged level and return to the user level by entering disable at the prompt as follows:

Router# disable

Router>

To check the interface configuration using show commands, proceed to the section "Checking the Configuration" on page 40.

Upgrading Microcode

At system startup or reload, the system loads a microcode image for each processor type. The factory default for systems running Maintenance Release 9.17(6) and earlier is to load the images from the individual microcode ROMs on the processors. The default for systems running Maintenance Release 9.17(7) and later is to bypass the ROM microcode and load the microcode images bundled with the system image. All processors of the same type use the same microcode image; only one image for each type can load at startup. This section describes how to modify the startup configuration to load different microcode images at startup, or to change existing configuration instructions and reenable the system default.

Router# ping 131.131.101.101 <Return>
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 131.131.101.101, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/15/64 ms
Router#

Router> show version
GS Software (RSP-K), Version 10.3(6)
Copyright (c) 1986-1995 by cisco Systems, Inc.
Compiled Wed 10-May-95 01:16 

System Bootstrap, Version 4.6(1)

Current date and time is Wed 9-27-1995 2:18:52
Boot date and time is Wed 9-27-1995 11:42:38
Router uptime is 3 weeks, 6 days, 14 hours, 36 minutes
System restarted by power-on
Running default software
Network configuration file is "Router", booted via tftp from 1.1.1.333

Router# show controllers cxbus

Switch Processor 5, hardware version 11.1, microcode version 1.2
  [text omitted from example]
 FSIP 1, hardware version 1.0, microcode version 1.0
  Interface 8 - Serial1/0, electrical interface is V.35 DTE
  [text omitted from example]
  Interface 9 - Serial1/1, electrical interface is V.35 DTE
 [(remainder of displayed text omitted from example]

Router> show int hssi 1/0

Serial 1/0 is up, line protocol is up
  Hardware is cxBus FSIP
  Internet address is 1.1.1.9, subnet mask is 255.255.255.0
[display text omitted]

Router# show flash
4096K bytes of flash memory on embedded flash (in RP1).

file    offset      length      name
  0     0x80        53364       fip1-1
  1     0xD134      55410       sp1-2
  [4085336/4194304 bytes free]

Router# show config

Using 1652 out of 130048 bytes
version 9.17
!
hostname Router
!
enable-password guessagain
!
microcode TRIP flash trip1-0
microcode reload
!
interface serial1/0
ip address 1.1.1.67 
ip route-cache cbus
no keepalive
!
interface serial1/1
ip address 1.1.1.12 
[display text omitted]

Router> show protocols

Global values:
  Internet Protocol routing is enabled
Serial1/0 is up, line protocol is up
[display text omitted]