Cisco Broadband Cable, Справочное руководство

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Cisco Broadband Cable Command Reference Guide
OL-1581-08
Chapter 2 Cisco CMTS Configuration Commands
cable upstream ingress-noise-cancellation
cable upstream ingress-noise-cancellation
To configure how often a line card should train its noise-cancellation circuitry so as to adjust to noise
levels on the upstream, use the
cable upstream ingress-noise-cancellation command in cable interface
configuration mode. To disable the ingress noise cancellation feature, use the no form of this command.
cable upstream n ingress-noise-cancellation interval
no cable upstream n ingress-noise-cancellation
Syntax Description
Defaults 200 milliseconds
Command Modes Interface configuration (cable interface only)
Command History
Usage Guidelines Broadband Processing Engine (BPE) cable interface line cards, such as the Cisco uBR-MC28U/X cards,
contain advanced hardware-based noise cancellation circuitry that digitally removes in-channel
impairments such as ingress, common path distortion, and certain types of impulse noise. To configure
how often these line cards should train their noise cancellation circuity, so as to adapt to changes in the
noise types and levels, use the
cable upstream ingress-noise-cancellation command.
When you enable ingress noise cancellation on an upstream, the Cisco CMTS periodically schedules a
256-symbol idle slot on the upstream channel. The
interval option specified in the cable upstream
ingress-noise-cancellation command determines how often this idle slot is generated.
The default for BPE cards is for the card to train its circuitry every 200 milliseconds. The smaller the
triggering interval, the faster the card can adjust to changes in ingress noise, which makes the upstream
more robust to noise problems, but at the cost of decreasing bandwidth on the upstream channel. To
determine the bandwidth cost, in percentage of raw bandwidth, use the following formula:
(256/ interval )/ channel-symbol-rate
n Specifies the upstream port number. Valid values start with 0 for the first
upstream port on the cable interface line card.
interval Triggering interval, in milliseconds. The valid range is 10 to 3000
milliseconds, with a default value of 200 milliseconds.
Release Modification
12.2(15)CX This command was introduced for the Cisco uBR-MC16U/X and
Cisco uBR-MC28U/X cable interface line cards on the Cisco uBR7246VXR
router.
12.2(15)BC2 Support was added for the Cisco uBR-MC5X20U cable interface line card
on the Cisco uBR10012 router.