Configuring Headend Broadband Access Router Features
Configuring the Upstream Cable Interface
MC-552
Cisco IOS Multiservice Applications Configuration Guide
Caution The upstream scrambler must be activated for normal operation. Disabling it can result in
corrupted packets. Disable it only for prototype modems that do not support scrambler.
To activate the upstream scrambler after it has been disabled, use the following command in cable
interface configuration mode:
Verifying the Upstream Scrambler
To verify whether or not the upstream scrambler is activated, enter the more system:running-config
command and look for the cable interface configuration information. The following is an excerpt from
the more system:running-config command output:
CMTS01# more system:running-config
Building configuration...
Current 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
To troubleshoot the configuration, perform the following tasks:
• Make sure the cable connections are not loose or disconnected.
• Make sure the Cisco cable modem card is firmly seated in its chassis slot and the captive installation
screws are tight.
• Make sure you entered the correct slot and port numbers when you typed the command.
• Make sure you entered the correct upstream port number:
–
On the MC16C cable modem card, this can be u0 to u5.
–
On the MC14C cable modem card, this can be u0 to u3.
–
On the MC12C cable modem card, this can be u0 or u1.
–
On the MC11C cable modem card, this can be u0 only.
Command Purpose
CMTS01(config-if)# cable upstream usport scrambler
Enables the scrambler. This is the default.
