Cisco Systems MC-607 manual Service Assignments, MC-613

Configuring Subscriber-End Broadband Access Router Features

Subscriber-End Broadband Access Router Data Operations

Table 38 Cisco uBR900 Series Cable Access Router Data Specifications (continued)

Description	Downstream Values		Upstream Values
Signal-to-Noise Ratio	64 QAM:		QPSK:
(SNR)	>23.5 dB @ BER<10^8		>15 dB @ BER<10^-8
			(QPSK will work at 98%
	256 QAM*:		successful ping rate for SNR
	>30 dB @ BER <10^-8		>13 dB. A SNR of 15 dB will be
	(For input level from +15 to -8 dBmV,		needed to get almost optimal
	SNR must be greater than 30 dB. For		packets per minute transition.)
	input level from -8 to -15 dBmV, SNR
	must be greater than 33 dB.)
			16 QAM:
			>22 dB @ BER <10^-8
	Note These performance numbers are		(For 16 QAM, a SNR >22 dB
		in laboratory-controlled	makes the grade for 98% ping
		conditions against statistically	efficiency. To get good packet rate,
		pure noise sources (AWGN).	you need SNR >25 dB).
		Because such conditions do not
		exist in practice, a 6 dB or more
		SNR margin is required for	Note These measurements were
		reliable operation. Check with		made for 0 and –10 dBmV
		your local system guidelines.		input to the CMTS,
				1280 kilosymbols/second,
				and 64 bytes packet size
				with a Cisco uBR904 cable
				access router and
				laboratory-controlled
				conditions.
Security	DES decryption: DOCSIS Baseline		DES encryption
	Privacy (BPI), 40-bit, 56-bit, and 168-bit
	DES encryption, as controlled by the
	headend and configuration files.
	Note Cisco IOS images must contain
		encryption software at both the
		CMTS and the Cisco uBR900
		series. Both routers must be
		enabled and properly configured
		to support encryption.

Service Assignments

Each Cisco uBR900 series cable access router on the network is configured to receive data on a particular downstream channel. A downstream channel contains upstream segment(s). Each upstream segment typically serves more than one fiber node.

Cisco IOS Multiservice Applications Configuration Guide

MC-613