Cisco Systems MC-607 Data Specifications, Description Downstream Values Upstream Values, MC-612

Configuring Subscriber-End Broadband Access Router Features

Subscriber-End Broadband Access Router Data Operations

The system uses TCP/IP to transmit data. TCP/IP transmits data in segments encased in IP datagrams, along with checksums to detect data corruption and sequence numbers to ensure an ordered byte stream on the TCP connection between the Cisco cable access router and the CMTS.

Cisco cable access routers also support multicast services—data streams sent to groups of subscribers. These applications utilize the User Datagram Protocol (UDP) instead of TCP. Because UDP does not mandate upstream acknowledgments, these applications can be very efficient in the network. Additionally, restricting upstream throughput will have no effect on downstream UDP streaming throughput.

Note Interactive games are the exception. Although low latency is required in gaming applications, high upstream data throughput is not demanded because the volume of data transmitted upstream is typically small.

Data Specifications

Table 37 provides a summary of the upstream and downstream transmission characteristics of the Cisco uBR900 series cable access routers.

Table 38 Cisco uBR900 Series Cable Access Router Data Specifications

Description	Downstream Values		Upstream Values
Frequency Range	88 to 860 MHz		5 to 42 MHz
Modulation	64 QAM		QPSK
	256 QAM		16 QAM
Data Rate	30 Mbps/64 QAM		QPSK—320 kbps to 5 Mbps
	(27 Mbps after FEC overhead)
	42.8 Mbps/256 QAM		16 QAM—640 kbps to 10 Mbps
	(36 Mbps after FEC overhead)
Bandwidth	6 MHz		200 kHz, 400 kHz, 800 kHz,
			1.6 MHz,
			3.2 MHz
FEC	RS (122, 128) Trellis		Reed Solomon
One Channel	Receive level of digital signal		QPSK— +8 to +58 dBmV
	–15 to +15 dBmV
			16 QAM— +8 to +55 dBmV
	Note Most field measurements are of
		nearby or adjacent analog signal
		which is normally +6 to +10 dB
		(system specific) above the
		digital signal level.

Cisco IOS Multiservice Applications Configuration Guide

MC-612