Cisco Systems UBR7225VXR Connecting and Configuring the Upstream, Docsis Specification

Chapter 4 Connecting the Cisco uBR7225VXR Router to the Cable Headend

Connecting and Configuring the Upstream

Connecting and Configuring the Upstream

The following sections describe how to connect and configure the upstream for digital data.

Connecting the Upstream to the Optical Receiver

To connect the upstream to the optical receiver, use a 2-way splitter as a combiner to leave the DOCSIS cable modem connected at the headend, and connect the upstream headend cable to the optical receiver. (See Figure 4-22.)

The default upstream input level to the Cisco uBR7225VXR cable interface line card is 0 dBmV. You may adjust the upstream input level to other values using the Cisco IOS software running on your router. The Cisco uBR7225VXR router uses automatic power control when transmitting to remote

cable modems. Accurately setting the power level helps to ensure reliable cable modem operation.

Table 4-1provides upstream input power ranges for the various cable interface line cards available for the Cisco uBR7225VXR router, depending on the channel bandwidth you are using.

Table 4-1	Upstream Input Power Ranges According to Cable Interface Line Card Type
Channel Bandwidth		Cisco MC11 FPGA	Cisco MC16E and MC16S	DOCSIS Specification
200 KHz		N/A	–10 to +25 dBmV	–16 to +14 dBmV
400 KHz		N/A	–10 to +25 dBmV	–13 to +17 dBmV
800 KHz		N/A	–10 to +25 dBmV	–10 to +20 dBmV
1.6 MHz		–10 to +10 dBmV	–10 to +25 dBmV	–7 to +23 dBmV
3.2 MHz		N/A	–10 to +25 dBmV	–4 to +26 dBmV

Note If you have a Cisco uBRMC16x cable interface line card (six upstream ports and one downstream port) installed in your Cisco uBR7225VXR router, the 2-way splitter described above would be replaced by six 2-way splitters (one splitter per upstream port). This would enable you to connect to all of the available upstream ports on the Cisco uBRMC16x.

	Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide
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