Installation guide

27
Release Notes for Cisco uBR7200 Series for Cisco IOS Release 12.1 T
78-10643-04 Rev. B0
New and Changed Information
Cisco Cable Clock Card
The Cisco Cable Clock Card enables the uBR7246 VXR to synchronize to an external T1 timing source
and propagate the clock to the downstream DOCSIS-based cable access routers. It is designed for cable
networks running VoIP applications.
When installed in the Cisco uBR7246 VXR chassis, the Cisco Cable Clock Card can propagate a
national clock signal throughout the router’s midplane by locking onto an external T1 signal originating
over the PSTN, locking onto a T1 clock signal originating from a port adapter installed in the same
chassis, or connecting to a GPS receiver generating a T1 clock signal.
Spectrum Management Cable Modem Card (MC16S)
The software for the MC16S Spectrum Management Cable Modem Cards is a driver running on the
Cisco uBR7200 Series Universal Broadband Routers. Using a Peripheral Component Interconnect
(PCI) interface, the Universal Broadband Router line card software interacts with the cable modem
card. Data is passed back and forth, as direct memory access (DMA) transfers, from the
Cisco uBR7200’s memory to the cable modem card.
Additionally, the MC16S Cable Modem Cards support Universal Broadband Router line card
management and control with the modem card Management Information Bases (MIBs), Media Access
Control (MAC) control software, and logical link management software based on DOCSIS standards.
In addition to its cable modem card, the MC16S provides dedicated hardware support for advanced
spectrum management through a daughter spectrum management card. This card contains a spectrum
analyzer that samples the 5- to 42-MHz upstream frequency spectrum in real-time, analyzing the
number of offline cable modems. If a user-defined threshold value is reached, the spectrum management
card takes a snapshot of the available upstream spectrum and passes that information to the IOS
software, which analyzes it for possible significant ingress and impulse noise.
Using this analysis, the IOS software evaluates the upstream frequency spectrum and, if necessary
automatically hops to a frequency that can provide a clean upstream channel. This eliminates “blind”
frequency hops and can improve response time to ingress noise impairments.
The cable upstream interface command now includes a new parameter when used to configure an
interface on the MC16S Cable Modem Card, to allow the creation of a range of channel width. The new
syntax is cable upstream port channel-width channel-width-1 channel-width-2 where the possible
channel width values are 200000, 400000, 800000, 1600000, 3200000.
The cable upstream port modulation-profile modulation-number command configures the upstream
modulation profile.
Note The MC16S Spectrum Management Card is calibrated using a 24.016 MHz, 0 dBmV
reference signal injected into the card’s front F-connector. The worst case accuracy is
specified as +/- 3 dB over the DOCSIS upstream frequency band (5-45 MHz) and
operating temperature range (0 to 40 degrees Centigrade).