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Activate the Upstream Scrambler
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.
Caution 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:
Command Purpose
cable upstream port scrambler Enable the scrambler.