Attaching the PA-8T-V.35 Interface Cables

To continue your PA-8T-V.35 port adapter installation, you must install the port adapter cables. The instructions that follow apply to all supported platforms. This chapter contains the following sections:

Connecting a PA-8T-V.35 Compact Serial Cable

On a single PA-8T-V.35, you can use only one compact serial cable. PA-8T-V.35 compact serial cables are available only from Cisco Systems.

Caution You can attach only an EIA/TIA-V.35 compact serial cable to the PA-8T-V.35 installed in your router. Attaching a compact serial cable of another interface type to the port adapter could damage your router or the hardware at the network end of the cable.

Use the following procedure to connect a compact serial cable to a PA-8T-V.35:

Step 1 Attach the compact serial cable directly to the receptacle on the PA-8T-V.35 and tighten the strain-relief screws. (See Figure 4-1.)

Note Port adapters have a handle attached, but this handle is not shown to allow a full detailed view of each port adapter's faceplate.

When attaching the cable receptacle on the PA-8T-V.35, use the cable-management bracket that shipped with your router for extra strain relief.

Figure 4-1: Connecting a PA-8T-V.35 Compact Serial Cable---Front View (Shown Without Handle)

Caution You must attach compact serial cables correctly or damage to the cable plug will result. Attempting to force a cable plug on the 200-pin receptacle can damage the plug. (See Figure 4-2.)

Figure 4-2: Connecting the Compact Serial Cable

Step 2 Attach the network end of your serial cable to your data service unit (DSU), channel service unit (CSU), data terminal equipment (DTE), or other external synchronous-serial equipment and tighten the strain-relief screws.

This completes the procedure for attaching a PA-8T-V.35 compact serial cable to the PA-8T-V.35. If you need to replace an PA-8T-V.35 compact serial cable, proceed to the "Determining the Port Mode" section; otherwise, proceed to "Configuring the PA-8T-V.35 Interfaces."

Determining the Port Mode

The compact serial cable connected to each port determines the mode of the ports (the electrical interface type is always V.35). The default mode of the ports is data communications equipment (DCE), which allows you to perform a loopback test on any port without having to attach a port adapter cable. For information related to the loopback command, see the "Using the ping Command to Verify Network Connectivity" section. Although DCE is the default, there is no default clock rate set on the interfaces. On the Cisco 7100 series, Cisco 7200 series, or the Cisco uBR7200 series router when there is no cable attached to a port, the software actually identifies the port as cable type: None present rather than either a DTE or a DCE interface. On a Catalyst RSM/VIP, the Catalyst 6000 family FlexWAN module, and VIP2, 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 a DCE interface.

Following is an example of the show controllers serial command that shows a Cisco 7100 series router, a Cisco 7200 series router, or a Cisco uBR7200 series router interface port (1/0) that has a V.35 DTE cable attached:

Router# show controllers serial 1/0
 
M8T-V.35: show controller:
PAS unit 0, subunit 0, f/w version 1-19, Rev id 0x2800001, version 2
idb = 0x60942688, ds = 0x608A6570, ssb=0x608C6CF0
Clock mux=0x0, ucmd_ctrl=0x1C, port_status=0xC
maxdgram=1524, bufpool=32Kb, 64 particles
     DCD=up  DSR=up  DTR=down  RTS=down  CTS=up
line state: down
cable type : V.35 DCE cable, received clockrate 123984
[display text omitted]

Following is an example of the show controllers cbus command that shows a VIP2 interface port (2/1/0) that has a V.35 DTE cable attached:

Router# show controllers cbus
 
slot2: VIP2, hw 2.2, sw 21.40, ccb 5800FFA0, cmdq 480000C0, vps 8192
    software loaded from flash slot0:muck/amcrae/vip2_21-40.mxt
    FLASH ROM version 255.255
   Mueslix Serial(8), HW Revision 0x1, FW Revision 1.20
    Serial2/1/0, applique is V.35 DTE
      gfreeq 48000140, lfreeq 480001B0 (1536 bytes), throttled 0
      rxlo 4, rxhi 90, rxcurr 0, maxrxcurr 0
txq 48001A80, txacc 48001A82 (value 58), txlimit 58
[display text omitted]

Following is an example of the show controllers cbus command that shows a Catalyst RSM/VIP interface port (1/0) that has a V.35 DTE cable attached:

Note The slot values displayed by some commands (such as show diag and show controllers cbus) are not relevant to any physical connection; disregard these slot values.

Router# show controllers cbus
 
slot9: VIP2, hw 2.0, sw 22.20, ccb 5800FFB0, cmdq 480000C8, vps 8192
    software loaded from system
    IOS (tm) VIP Software (SVIP-DW-M), Version 11.2(0.201), BETA TEST SOFTWARE
    ROM Monitor version 17.0
    Serial1/0, applique is V.35 DTE
    gfreeq 48000140, lfreeq 480001B0 (1536 bytes), throttled 0
    rxlo 4, rxhi 90, rxcurr 0, maxrxcurr 0
    txq 48001A80, txacc 48001A82 (value 58), txlimit 58
    [display text omitted]

To change the mode of a port online, use software commands to shut down the interface, replace the compact serial cable, restart the interface, and (if necessary) reconfigure the port for the new interface. At system startup or restart, the system polls the interfaces and determines the electrical interface type of each port (according to the type of compact serial cable attached). However, the system 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.

If you are replacing a cable with a cable that has the same mode, these steps are not necessary (simply replace the cable without interrupting operation).

Step 1 Enter configuration mode. At the privileged level of the EXEC, specify the port address and shut down the interface. (See the "Using the EXEC Command Interpreter" section for an explanation of the privileged level of the EXEC.) Add additional configuration commands, if needed, before you exit from configuration mode (before you press Ctrl-Z or enter end).

For a Cisco 7200 series, a Cisco 7100 series, a Cisco uBR7200 series router, or a Catalyst RSM/VIP2, use the following example:

Router> enable
Password: 
Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface serial 1/0
Router(config-if)# shutdown
Ctrl-Z
Router#

For a VIP2, use the following example:

Router> enable
Password: 
Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface serial 3/1/0
Router(config-if)# shutdown
Ctrl-Z
Router#

Step 2 Locate and remove the adapter cable to be replaced.

Step 3 Connect the new cable between the PA-8T-V.35 and the network connection. Tighten the thumbscrews at both ends of the cable to secure it in the ports.

Step 4 Enter configuration mode again, bring the port back up, and save the running configuration to NVRAM.

For a Cisco 7100 series2, Cisco 7200 series, a Cisco uBR7200 series router, or a Catalyst RSM/VIP, use the following example:

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface serial 1/0
Router(config-if)# no shutdown
Ctrl-Z
Router#
 
Router# copy running-config startup-config

These steps prompt the system to poll the interface and recognize the 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 remains down and does 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 uses the external clock signal from the remote DCE device and ignores the internal clock signal that the DCE interface normally uses. Therefore, when 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.

This completes the procedure for replacing a PA-8T-V.35 compact serial cable on the PA-8T-V.35. Proceed to "Configuring the PA-8T-V.35 Interfaces."

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