Cisco Systems uBR7246 Manual De Usuario

 Configuring Cisco uBR7246 Universal Broadband Router Features VC-147

Validation Tips

To verify if FEC is activated or deactivated, enter the command more system:running-config and 
look for the cable interface configuration information. The following is an excerpt from the more 
system:running-config command output.

router# more system:running-config

Building configuration...

 

!

interface Cable6/0

 ip address 1.1.1.1 255.255.255.0

 no keepalive

 cable insertion-interval 150000

 cable downstream annex B

 cable downstream modulation 64qam

 cable downstream interleave-depth 32

 cable downstream symbol-rate 5056941

 cable upstream 0 frequency 15008000

 cable upstream 0 fec

 cable upstream 0 scrambler

 no cable upstream 0 shutdown

!

Troubleshooting Tips

If you are having trouble: 

•

Make sure the cable connections are not loose or disconnected. 

•

Make sure the cable modem card is firmly seated in its Cisco uBR7246 chassis slot.

•

Make sure that you have entered the correct slot and port numbers when you typed the command.

•

Make sure that you have entered the correct upstream port number. Currently this is always u0.

Activate the Upstream Scrambler

The scrambler on the upstream RF carrier enables cable modems on the HFC network to use built-in 
scrambler circuitry for upstream data transmissions. The scrambler circuitry improves reliability of 
the upstream receiver on the cable modem card. The upstream scrambler is activated by default and 
should not be disabled.

The Scrambler must be activated for normal operation. Deactivate only for prototype modems that 

do not support scrambler.

To activate the upstream scrambler, use the following command in cable interface configuration 
mode:

cable upstream port scrambler

Enable the scrambler.