Troubleshooting A Modem Connection To A Lucent  PortMaster ® 3 And PortMaster 4

Perform the following tasks to troubleshoot a modem dial in user who is having trouble connecting to a Lucent PortMaster® 3 or PortMaster 4: 

Follow these instructions for each modem having trouble dialing in to the Lucent PortMaster 3 or 4. Lucent InterNetworking Systems Technical Support handles every modem problem as a separate issue on separate trouble tickets. This information is required to minimize delays in finding a solution. 

Task 1: Check The Modem Hardware.

Perform this task if you have a PortMaster 3 and the problem at the customer site can be described as excessive retrains or excessive failures to connect on dial in. 

In August 1998, the InterNetworking Systems of Lucent Technologies announced a hardware recall and replacement of certain 56Kbps 8-port or 10-port modem boards on the PortMaster 3. The board must meet BOTH revision and date code criteria to be part of the replacement program: 

  • The bar code label must show revision F or G.
  • The date code to the right of the bar code label must be 98xx. 

Task 2: Verify The Lucent ComOS® Version.

Make sure the PortMaster is running the latest version of Lucent ComOs®  by checking http://www.ra.lucent.com/forms/one-click-dnload.cgi. Download the latest ComOS version, if necessary. 

If you are upgrading a PortMaster  and the customer is running the Microsoft Windows 95 or Windows 98 operating system and using a Rockwell HCF modem, see http://www.ra.lucent.com/tech/bulletin/comos-modem.html for more information. 

Task 3: Check The T1 Line Condition.

Perform this task if the problem at the customer site can be described as excessive retrains or excessive failures to connect on dial in. 

Do the following to check the channelized T1 or ISDN PRI line condition: 

  1. Type the Commands>  show line0 and show line1 and examine the display. 
  2. Verify that the status is UP. 
  3. Verify with your telecommunications service provider that the framing format and encoding method are correct for both directions. 
  4. Verify the signaling. If it is E & M wink start, channelized T1 expects no Directory Number Identification Service (DNIS) digits although a DMS-10 switch expects 1 DNIS digit.  PRI expects from 7 to 10 DNIS digits.
  5. Verify that receive levels range from +2dB to -15dB. 
  6. Verify that no alarms or violations are present. Enter Command> show line0 and show line1 every half hour. If you notice the Alarms or Violations counters increasing over time, contact your T1 service provider. Your line may be experiencing a condition that your provider needs to correct, or the provider maybe performing a test on your line. 
  7. Reboot the PortMaster  to bring the output counters to zero, make sure no line tests are being done on your line.  Monitor any line errors that start to increment a line.
    • If the errors continue to increment, contact Lucent InterNetworking Systems Technical Support to open a trouble ticket.  These types of problems are usually handled  by the Wide Area Network (WAN) team within the technical support group.
    • If  a few errors reappear directly after the reboot but  are not incrementing  proceed to Task 4: Upgrade your customer  modem firmware. 

Task 4: Upgrade The Customer Modem Firmware.

Contact the dial in user with the problem modem and work with that person to resolve the problem. Upgrade the modem to the latest firmware to resolve known problems. The modem must be running the latest V.90 software released by the modem manufacturer. 

If the customer has a problem connecting, try the following procedures: 

  • Turn off flow control. 
  • Force V.90 through the modem AT commands. 
  • Try adding 2 to 5 commas after the dial string. 

Read the following sections for details and websites on common modem manufactures. 

LT Win Modem 

  • For LT Win Modems having slow speeds and disconnection problems when dialing in to a PortMaster running Lucent ComOS ® 3.8 or later, try entering -v90=1 to enable V.90 on the modem. 
  • You may need to have the modem ignore the V.8 tone, by adding 2 to 4 commas after the dial string. 
  • For LT Win Modem driver updates, see:  http://www.808hi.com/56k/x2-lucent.htm#firmware or http://56k.com/reports/ltfaq.shtml. 

For technical support for Lucent LT Win Modem, call 1-800-372-2447. 

COMPAQ HCF 
Compaq has a fix for the connectivity problem of the HCF Rockwell modems in their Presario computers. Some line impairments at the local telephone company loop levels might limit connections to V.34, but the connections stay up. See http://www.compaq.com/athome/support/softpaq/sp_desk.html for both modem driver and ROM updates. Call Compaq if you do not see your model listed. 

3Com/U.S. Robotics (USR) 
See http://www.usr.com/home/online/. 

Acer HCF 
See ftp://ftp.acer.com/aac_support/desktop/drivers/modem/. 

Diamond SupraExpress K56flex Modems 
See http://www.diamondmm.com/56k/v90-upgrade.html. 

Task 5: Test The Customer Modem.

Step 1: Test modem dialing end-to-end: 

The "first mile" is the local loop between the customer and their telephone company central office. The "last mile" is the local loop between the PortMaster  and its local telecommunications service provider. The service provider is in the middle. 

Ask the customer to test the first mile, service provider, and last mile by dialing in to your PortMaster . If the customer displays low connection speeds or disconnects while dialing in, proceed to Step 2: Test the first and last mile. 

Step 2: Test the first and last mile: 

Ask the customer to dial in to the PortMaster using a long distance code.  For example: 1010321-1-950-555-1212. By dialing 1010321, you are forcing the call through a different telephone switch, (the long distance telephone switch). If the connection speeds do not change when the customer dials through the long distance switch, continue to Step 3: Test the first mile only. 

If the customer is connecting at higher speeds with the long distance carrier, the problem is with the local service provider. The customer must inform their local telephone company that they can connect properly through a different switch, but the line conditions are preventing them from connecting through the local switch at higher speeds. 

The following are examples of other long distance carrier codes: 

  • MCI---1010222 
  • AT&T---1010288 
  • Sprint---1010333 

Note: These codes are for United States customers only and might not work in Canada, Australia, New Zealand, and South America. Ask non U.S. customers to check with an operator for a long distance code option. 

If your customer dials other long distance carrier codes and the telephone call does not go through, their local switch is not configured to allow these types of calls. Continue to Step 3: Test the first mile only. 

Step 3: Test the first mile only: 

Ask the customer to do the following: 

  1. Set a HyperTerminal terminal emulator for 8 data bits,1 stop bit, and no parity (N). 
  2. Dial 1-847-262-6000 to reach the USR Support BBS - Total Control Rack for modem testing and connection analysis. 
  3. Once connected, and prompted for graphics, enter N for no. 
  4. Enter the following: First name= line Last name= test. 
  5. Check for the following banner at the end of the test: "This connection supports 56K technology" 
    • If the banner appears, the line is likely able to connect to V.90 technology. (This test is not guaranteed accurate.) Go on to Step 6. 
    • If  the banner does not appear, the path connected from end to end is not compatible with V.90 or 56Kbps connections. The incompatibility prevents the customer from achieving connection higher than V.32 (33,600bps). Ask your customer to call their local service provider for further troubleshooting. 

    Note:  A customer using an X2-only modem cannot get better than a V.34 connection to a PortMaster  even if he or she appears to connect at 56Kbps to the USR test site. X2 is a proprietary protocol, and 56Kbps line diagnostics are not modem dependent. A V.34 modem will also incorrectly show a 56Kbps connection to the USR test site. 

  6. Dial 1-713-693-0399 to access the Houston Area League of PC Users test site. 
  7. Display format in text. 
  8. Copy in text formats and email or fax them to Lucent InterNetworking Systems Technical Support. 

Task 6: Check Ethernet Collisions.

Perform this task if the problem at the customer site can be described as slow or poor throughput on dial in. 

Check your collision domain by observing the collision lights, or network interface statistics. A rule of thumb is not to have more than two PortMaster 3's on the same collision domain. 

  1. Enter Command> show netstat to display the number of collisions (Collis) and output packets (Opkts). 
  2. Locate the counts for input errors (Ierrs) and output errors (Oerrs), collisions (Collis), and resets. 
    • Collisions greater than 5 percent of total output indicate an overloaded network or an Ethernet hardware failure.  For example:  A failed cable, hub, or network interface card (NIC). 
    • Lots of resets usually found in remote LANs indicate an overloaded network. 

Task 7: Receive Additional Support.

If you are still having modem problems that need to be addressed, go on to Modem Information Sheet for the PortMaster 3 and 4 (seen below).

Recommended Reading 
http://www.808hi.com/56K/ 

Modem Information Sheet For The Lucent PortMaster ® 3 and 4

Collect the following information about your PortMaster 3 or 4  the modem, and the modem user to help your technical support engineer solve the problem. The best  way to isolate a modem dial in problem is for the Lucent InterNetworking Systems Technical Support team to treat  modems from different manufacturers and models as separate trouble issues on separate trouble tickets. 

Step 1. Collect PortMaster Information: 

T1 type and signaling
ISDN PRI switch type
Telephone number to dial in on for testing
IP address to telnet in to for analysis
!root password for your PortMaster

Step 2. Collect Dialing Customer Information: 

Username
Telephone number and area prefix calling from
Telephone number and area prefix calling to
Computer operating system
Does the modem disconnect before, during, or after negotiation?

Do other customers dialing in with the same modems have the same problem? If so, explain briefly. 

In addition, use HyperTerminal terminal emulation software to collect the following information from the modem: 

Enter ati3---modem firmware version (in numerical format).
Enter ati6---hardware information or link diagnostics.
Enter ati7---for a configuration screen. Is V.90 is enabled?
Enter ati11---specific information about modem operation.
Enter aty11---diagnostics only for 3Com/USR modems.

Step 3. Report The Information. 

Email the information you have gathered to your technical support engineer. Enter your ticket number in the subject header. A Level 3 technician will contact you either by telephone or email. The technician will log in to your PortMaster to run diagnostics to get additional information for further analysis. 

This information is necessary to enable Lucent InterNetworking Systems to identify and resolve the problem in a timely manner. Thank you for your cooperation. 

Recommended Reading 
http://www.808hi.com/56K/ 

(c) 1999 Lucent Technologies. All rights reserved. 

PortMaster®, ComOS®, and ChoiceNet® are registered trademarks of Lucent Technologies, Inc. RADIUS ABM®, PMVision®, IRX®, and Port Authority® are trademarks of Lucent Technologies, Inc. All other marks are the property of their respective owners. 

Rev: 1G Page 1 of 1 Date 5/6/99