Table of Contents

Troubleshooting Overview
Initialization and Self-Test Problems
Troubleshooting Subsystems

Power Subsystem
Coaxial Cable Subsystem
RF and Digital Subsystem
PC Subsystem
VoIP Subsystem

Using the Reset Switch
Further Contacts

Troubleshooting

This chapter provides basic installation troubleshooting information. The chapter includes the following sections:

• Troubleshooting Overview

• Initialization and Self-Test Problems

• Troubleshooting Subsystems

• Using the Reset Switch

• Further Contacts

Troubleshooting Overview

Installation problems with Cisco uBR924 cable access routers are commonly due to the cable system and its topography. LEDs on the front panel of the Cisco uBR924 cable access router, shown in Figure 4-1, reveal operational status and help you determine problem areas. Refer to Table 3-2 in the"Viewing the Router's Initialization" section of Chapter 3 for a description of these LEDs.

Initialization and Self-Test Problems

When the Cisco uBR924 cable access router first powers on, the following occurs:

Step 1 The router runs self-test and diagnostic procedures. All LEDs (except for the four Ethernet LEDs and the ACT LED) briefly light and then turn off when self-test and diagnostic procedures are successful. The procedures ensure Cisco uBR924 components are functioning. To complete all self-test and diagnostic procedures, the Cisco uBR924 processor must be able to:

• Perform a system reset trap.

• Fetch and execute instructions from the ROM Monitor area of the bootflash chip.

• Write several internal registers and reset the control program without crashing.

• Correctly configure the port A and port D registers.

• Perform conditional branches.

• Ensure all software-controlled LEDs are functional.

Step 2 If a failure exists, different LEDs---V OK, V1, V2, DS, US, and DSNR---light and remain on to isolate a failure. Since the Cisco uBR924 is tested at the factory, these occurrences are rare in the field:

• The initialization assembly code calls an initialization routine. This routine initializes the memory controller and outputs the following code to the LEDs if a processor or memory control problem exists. The DS and DSNR LEDs light and remain on. All other LEDs remain off. The console is initialized and the banner is output to the console port if connected.

• If the above routine passes successfully, the initialization assembly code then calls the main initialization routine. A self-test is performed on the low registers of the Dynamic Random Access Memory (DRAM). If a problem exists, the V2, the DS, and the DSNR LEDs light and remain on to denote a processor cache failure. All other LEDs remain off.

• On successful completion, the next self-test is run. If this fails, the V-OK, V2, DS, and DSNR LEDs light and remain on. All other LEDs remain off. This denotes a possible memory or controller problem.

• After clearing the BSS area of the DRAM, if the V2, DS, and US LEDs light and remain on and all other LEDs are off, this denotes a possible memory or controller problem.

• After clearing the rest of DRAM, if the DS LED lights and remains on, while all other LEDs remain off, this indicates a possible memory or controller problem as well.

After the main initialization routine successfully completes, all LEDs turn off.

Step 3 The OK (power) LED then blinks while the router boots a Cisco IOS software image. Once finished, the OK LED remains on. If the LED does not start to blink, proceed to the troubleshooting "Power Subsystem" section.

Step 4 The DS, US, DSNR and LINK LEDs then remain on to indicate the router is operational and receiving a healthy signal:

• The DS LED indicates the router is locked to a downstream channel.

• The US LED indicates the router has established connectivity with the CMTS and is operating within 6 dB of desired power level (generally within 3 dB).

• The LINK LED indicates the cable interface is operational.

• The V OK LED indicates the VoIP system is healthy.

• The DSNR LED indicates the router is receiving a good downstream signal that is 5 dB above the downstream lock threshold.

---

Note Because SNR and lock threshold can drift, the SNR and lock threshold are checked every maintenance interval and the LED updated. The LED should be on under normal conditions.

---

Step 5 The Ethernet LEDs (labeled 1, 2, 3, and 4) and the ACT LED on the router light when a subscriber requests data using a computer connected to the router. The LEDs blink when there is activity.

When the router and computer have booted successfully, you should be able to access an Internet web site. Access to a web site confirms that the router is configured correctly. If you cannot access a web site, proceed to the troubleshooting "PC Subsystem" section.

Step 6 The voice LEDs (V1 and V2) on the router light when a subscriber establishes a VoIP connection. If you do not have dial tone on the Cisco uBR924 voice ports and cannot establish a VoIP connection, proceed to the troubleshooting "VoIP Subsystem" section.

Troubleshooting Subsystems

The key to troubleshooting is to isolate a problem to a specific subsystem:

• Power subsystem

• Coaxial cable subsystem

• RF and digital signal subsystem

• PC subsystem

• VoIP subsystem

Figure 4-2 on the next page provides a general troubleshooting flowchart. Table 4-1 and Table 4-2 help you correlate LED behavior with possible problems, and suggested courses of actions.

Figure 4-2: Basic Troubleshooting Strategy for Startup Problems

Power Subsystem

To help isolate a problem with the router power subsystem, look at the OK LED. Does the LED remain on when self-test is completed and a software image booted?

• If yes, the power source is good and the power supply is functional.

• If no, make sure the power cable is connected at the back of the router and that the power supply is properly connected to power at the wall outlet.

  • If the OK LED remains off, check the power source or power supply. Connect the power cord to another power source, if available. If the LED goes on, the problem is the first power source.

  • If the OK LED fails to blink after you connect the power cord to a new power source, the power supply is probably faulty.

Coaxial Cable Subsystem

The router will not function if the connection from the Cisco uBR924 cable access router to the CMTS is not established. There are many conditions inherent to coaxial cable that can inhibit this connection:

• Remove the coaxial cable from the back of the router. Is the center conductor on the coaxial cable end straight and of the correct length to ensure a good connection?

If the center conductor is not straight or appears to be too long or too short, cut the coaxial cable behind the connector end, and strip the insulation back. Make sure that the newly exposed center conductor is straight. Before replacing the new cable connector end, check the general condition of the cable. Make sure the new conductor end is securely crimped to the cable.

• Is the coaxial cable running to the router in excellent condition?

RF and Digital Subsystem

The use of RF and digital signals on the same cable can lead to interference if the HFC network is not correctly configured.

• Is the downstream video signal being received at the ground block or at the tap?

Connect a premium services cable converter to the ground block or at the tap and contact field service dispatch. Ask the CMTS system administrator to check if they can locate the box on the network by sending an impulse, or on-demand, video signal to the converter.

If field service can locate the converter at the ground block or at the tap, repeat the test with the router connected to the cable end near the computer.

If field service cannot locate the converter at the cable end, but can locate the converter at the ground block or tap, replace the cable from the ground block or tap to the cable end.

• Check the adjacent video channel. The digital data signal should be approximately in the range of -2 to +15 dBmV on a nearby analog channel. Confirm this value using a portable field strength meter, or power meter, to measure the adjacent analog video signal.

PC Subsystem

To isolate a problem with a PC that is connected to the Cisco uBR924 cable access router:

• Can you access a Web page using the Web browsing software installed on the computer?

If you cannot access a Web page, verify that the computer network protocol is configured for TCP/IP and that DHCP services are enabled using the following Windows 95 options:

(a) Turn on your PC and enter your network user name and password.

(b) Choose Start->Settings->Control Panel. The Control Panel appears.

(c) Double-click the Network icon. The Network window appears with the Configuration tab in the foreground. If the Configuration tab is not in the foreground, click this tab.

(d) Scroll the network components list box until the Ethernet adapter TCP/IP option displays for your network adapter and double-click the selection. The TCP/IP Properties window appears with the IP Address tab in the foreground. If the IP Address tab is not in the foreground, click this tab.

---

Note If there is no TCP/IP entry for the installed network adapter, the computer is not configured for IP. Refer to the subscriber's computer and network interface card user guides on how to configure these settings.

---

(e) Make sure that the radio button next to Obtain an IP address automatically is selected. If this radio button is not selected, the computer is not configured for DHCP. Select the Obtain an IP address automatically radio button now and save your configuration settings.

(f) Close all networking windows and close the Control Panel.

(g) Follow the onscreen instructions and reboot your PC.

• Is the network interface card operational?

Verify that the network card is installed properly and that necessary software drivers have been installed and are running on the computer. Consult the user guide or other documentation that accompanied the network card. Contact technical support for the network card manufacturer as necessary.

• Is the computer preconfigured to work with special software such as America Online? Some computers come with dialup adapters preconfigured to work with special software. To ensure the setup is correct, follow the procedures below.

Setting the Internet Properties:

(a) Turn on your PC and enter your network user name and password.

(b) Choose Start->Settings->Control Panel. The Control Panel appears.

(c) Double-click the Internet icon. The Internet Properties window appears with the General tab in the foreground.

(d) Click the Connection tab. The Internet Properties Connection tab displays. The Connect to the Internet: as needed check box is checked and the name of the dialup adapter appears in the Dial-Up Networking connection list box.

(e) Click the Connect to the Internet: as needed check box to deselect the option.

(f) Click OK.

(g) From the Control Panel, double-click the System icon. The System Properties window displays with the General tab in the foreground.

(h) Click the Device Manager tab.

(i) Click the Network adapter selection. Make sure the display contains no red "X" or yellow exclamation point.

(j) Click OK.

Setting Network Components:

(a) Turn on your PC and enter your network user name and password.

(b) Choose Start->Settings->Control Panel. The Control Panel appears.

(c) Double-click the Network icon. The Network window appears with the Configuration tab in the foreground.

(d) Scroll the list box until the particular dialup adapter selection appears. If the computer has America Online installed, two network components will be displayed: AOL Dialup Adapter and TCP/IP->AOL Dialup Adapter.

(e) If the subscriber does not intend to use America Online, remove both these components from the Network components list box:

• Click the AOL Dialup Adapter. The selection is highlighted. Click Remove.

• Click the TCP/IP->AOL Dialup Adapter. The selection is highlighted. Click Remove.

(f) If the subscriber intends to use America Online, double-click the TCP/IP component associated with the dialup adapter. The TCP/IP Properties window appears with the IP Address tab in the foreground.

(g) Click the Obtain an IP address automatically radio button. The IP address for the dialup connection will only be assigned when the connection is made. By default, the computer will be assigned an IP address by the Cisco uBR924 via DHCP.

(h) Click OK. A dialog box appears, informing you for the change to become effective, the computer must be rebooted.

(i) Click Yes to reboot the computer.

VoIP Subsystem

If you do not have dial tone when picking up a telephone or fax device connected to the Cisco uBR924 cable access router's voice ports, ensure the router is using a Cisco IOS image that supports voice. Refer to the "Cisco IOS Release Images" section of Chapter 1. Also refer to the "Downloading Specific Cisco IOS Images" section of Chapter 5.

Proceed to Table 4-2 on the next page. This table provides general VoIP troubleshooting tips.

Table 4-2: VoIP Troubleshooting Tips

LED	Status	Possible Problem	Suggested Action
V OK	Voice status LED is off for a router configured for voice.	VoIP system configuration problem.	Contact your provisioning or billing administrator or customer service department. If your provisioning or billing system is designed to support automatic feature upgrades, and the router's UID (cable MAC address) is already in the billing system and configured for use with voice, ask to have the router refreshed with the correct voice configuration. Note: This procedure can take several minutes.
V1 or V2	Voice port LED is off when a call on the port is initiated for a router configured for voice.	Bad telephone or fax machine connection. Bad cable. Equipment configuration problem.	Reseat the RJ-11 to RJ-11 cable at both ends for both the telephone and fax machine. Use a different cable. For a telephone, make sure a push button dial set is used. For fax, make sure the fax machine is on. If fax software is used, make sure the data mode is not used. Ensure a Cisco IOS Release 12.0(5)T image is used. If a two-line telephone is connected to the router, make sure it is connected to the V1+V2 rear connector. If a single line telephone is plugged into V2 at the same time a two-line telephone is plugged into V1+V2, the single-line telephone and line 2 of the two-line telephone act as if they are attached in parallel to V2. Make sure the sum of the RENs of all devices on any one telephone line does not exceed five (5.0) for subscriber sites that support multiple voice devices per telephone line.

Using the Reset Switch

The Cisco uBR924 cable access router contains a reset switch with three different actions:

• A quick press (less than 10 seconds) initiates a hardware reset, similar to a power cycle or software reload.

• Pressing the reset switch from between 10 and 30 seconds causes the router to clear its saved RF parameters and do a hardware reload. This reload is similar to plugging in the router for the first time.

• Pressing the reset switch for longer than 30 seconds causes the router to erase its system image and download a new system image over the cable interface should the CMTS system administrator have set certain options in the configuration file, in conjunction with field service personnel. The router then reboots with this new image.

Refer to Table 4-3 on the next page for additional elaboration.

Table 4-3: Reset Descriptions

Type of Reset	Press Reset Switch...	What Happens...
Warm	< 10 seconds	The router reboots, using the downstream frequencies saved in the configuration file.
Cold	10 to 29 seconds	The router reboots the image in flash, ignoring the downstream frequencies saved in the configuration file. The router initiates a downstream frequency search which may take a few minutes. The new frequencies are saved in the configuration file and are used at the next warm reset.
Cold	> than 30 seconds	The router downloads a new image from the CMTS and reboots storing this image in flash, assuming coordination between the CMTS system administrator and field personnel.

Further Contacts

If you experience trouble with the startup that is not resolved with the procedures and tips in this chapter, contact field service dispatch for further assistance and instructions. Also refer to the following Cisco IOS online document: Troubleshooting Tips for the Cisco uBR924 Cable Access Router.

Posted: Wed Aug 25 18:13:47 PDT 1999
Copyright 1989-1999©Cisco Systems Inc.