Cisco 626 ATM ADSL Modem User Guide
Troubleshooting
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Troubleshooting Basics

Troubleshooting Basics

Troubleshooting provides information on how to diagnose general operational issues for the Cisco 626 ATM ADSL Modem. There are some known issues described in this chapter as well as their solutions.

5.1 WAN LNK LED

If the WAN-LNK light does not appear "On" when you power up the modem, please wait for about 15 seconds. If after 15 seconds it does not appear on, double-check all cabling and connections. If the light does not appear at that point, please turn the power off and then on again. If the LED still does not appear lighted, please call your service representative. Should the PWR/ALARM light appear RED, please turn the power off and then on again. If the LED still appears RED, please call your service representative.

Note With the PWR/ALARM light "On", the WAN LNK light may appear "Off" under certain circumstances, even though the Cisco 626 is operating correctly. This condition can occur, for instance, if there is no data traffic across the WAN LNK for a period of time.
During subsequent requests for data across the link, the WAN LNK light starts to blink, This indicates the ADSL connection sequence has begun.

5.1.1 Reasons Why the WAN LNK LED Turns Off

1. If the WAN LNK LED blinks continuously and never stays solid on, the Cisco 626 never trains with the Cisco 6100 or Cisco 6200. There are a number of reasons why this would occur:

  • The ADSL line is not connected to the 626.

  • There are no available ATU-C's for the 626 to train up with.

  • The ADSL circuit is too long.

  • There is excessive noise on the ADSL circuit.



2. If the WAN LNK LED turns off after the Cisco 626 has successfully been transferring data end-to-end for some time, this means that the Cisco 626 or the Cisco 6100/6200 may have the SESSION timeout set, which affects the WAN LNK LED:

5.2 Serial Buffer Overflow

When using the serial port as your terminal connection, large amounts of serial data may overflow the serial buffer. This results in unintelligible ASCII appearing on the screen but does not affect performance or operation in any way. To avoid this, use Telnet to manage the Cisco 626.

5.3 Running Linux Without term/termcap

Computers running Linux without the "term"/"termcap" database installed will have trouble connecting to Cisco equipment. The message "BAD ADDRESS" is sometimes displayed as an error message. The user can install the term/termcap database from his/her Linux install disks/CD.

5.4 Clearing PC Cache With ARP

If you update IP addresses on many Cisco 626s in rapid succession using a Windows 95 PC, the PCs ARP cache may not clear right away. This causes communications problems with the subsequent Cisco 626s in the line. To clear the PC cache, use the following command at the MS-DOS prompt on your PC:

c:\> arp -d 192.168.0.100

This deletes the MAC address and causes IP to ARP again at IP address 192.168.0.100. The ARP utility comes with Windows 95 and WindowsNT.You can install it from your original Win95 or WinNT install disks/CD if it isn't in your current installation.