Cisco 678 Specifications download pdf (Page 140)

Chapter 6 Troubleshooting

Frequently Asked Questions about the WAN LNK LED

6-6

Cisco 600 Series Installation and Operation Guide

78-11190-01

three PPP requests to be sent from the CPE, and if they are not answered by

the service provider's equipment, the CPE stops sending them and the WAN

LNK LED turns off.

There are a number of possibilities why this would happen:

–

VPI/VCI provisioning is not correct in the ATM cloud. This could signify

that the service provider's equipment or the ATM switch along the path

does not have the correct provisioning.

–

VPI/VCI mapping in the service provider's equipment or the CPE is not

configured properly.

–

ATM Cell scrambling is enabled on one end of the link but not the other.

The

show running

command will display an entry with "

ATM WAN Cell

Scrambling = disabled

" if cell scrambling is disabled. No entry implies

the default behavior of ATM cell scrambling is enabled.

–

Service provider's equipment is powered off.

–

CPE is configured for routing mode, but the equipment at the service

provider's network that is terminating CPE traffic is configured for

bridging.

Use the

show errors

command to check the contents of the error log.

•

If the CPE trains up and the WAN LNK LED turns off, this is a sign of no

ATM cell delineation.Verify that you have the ATM link terminated at the

central office end. Without ATM cell delineation, the router will attempt to

retrain the line in 1 to 10 seconds.

•

If the CPE trains up and then immediately drops the connection, the near-end

DMT firmware might not be compatible with the far-end DMT firmware. For

example, an ITU G.Lite router might not train to an ANSI Issue 1 Central

Office. To see the DMT firmware version installed on your router, use the

show version

command.

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Cisco 678 Specifications Page 140

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