Installation guide

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Cisco uBR7100 Series Universal Broadband Router Software Configuration Guide
OL-2238-03
Chapter 3 Configuring the Cisco Cable Interface
Configuring the Upstream Cable Interface
3. Ensure the captive installation screws are tight.
4. Verify that you have entered the correct slot and port numbers.
5. Verify that you selected a valid frequency for your router.
Activating 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.
Caution The upstream scrambler is activated by default and should not be disabled under normal circumstances.
Disabling it can result in corrupted packets. Disable it only for prototype modems that do not support
the upstream scrambler.
To activate the upstream scrambler, use the following command in cable interface configuration mode.
The upstream scrambler is enabled by default.
CMTS01(config-if)# cable upstream usport scrambler
Verifying the Upstream Scrambler
To determine if the upstream scrambler is activated, enter the more system:running-config command
and look for the cable interface configuration information.
Perform these steps if you are having difficulty with verification:
1. Ensure the cable connections are not loose or disconnected.
2. Ensure the cable modem card is firmly seated in its chassis slot.
3. Ensure the captive installation screws are tight.
4. Verify that you have entered the correct slot and port numbers.
5. Verify that you selected a valid frequency for your router.
Activating Upstream Differential Encoding
To enable differential encoding on upstream traffic to a specified cable interface, use the following
command in cable interface configuration mode. Upstream differential encoding is enabled by default.
CMTS01(config-if)# cable upstream usport differential-encoding
Verifying Upstream Differential Encoding
To determine if upstream differential encoding is activated, enter the show running-config command
and look for the cable interface configuration information. If upstream differential encoding is enabled,
a differential encoding entry displays in the show running-config output. If upstream differential
encoding is disabled, no differential encoding entry displays in the output.
Perform these steps if you are having difficulty with verification:
1. Ensure the cable connections are not loose or disconnected.