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Configuring Subscriber-End Broadband Access Router Features
Subscriber-End Broadband Access Router Data Operations
MC-613
Cisco IOS Multiservice Applications Configuration Guide
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.
Signal-to-Noise Ratio
(SNR)
64 QAM:
>23.5 dB @ BER<10^8
256 QAM*:
>30 dB @ BER <10^-8
(For input level from +15 to -8 dBmV,
SNR must be greater than 30 dB. For
input level from -8 to -15 dBmV, SNR
must be greater than 33 dB.)
Note These performance numbers are
in laboratory-controlled
conditions against statistically
pure noise sources (AWGN).
Because such conditions do not
exist in practice, a 6 dB or more
SNR margin is required for
reliable operation. Check with
your local system guidelines.
QPSK:
>15 dB @ BER<10^-8
(QPSK will work at 98%
successful ping rate for SNR
>13 dB. A SNR of 15 dB will be
needed to get almost optimal
packets per minute transition.)
16 QAM:
>22 dB @ BER <10^-8
(For 16 QAM, a SNR >22 dB
makes the grade for 98% ping
efficiency. To get good packet rate,
you need SNR >25 dB).
Note These measurements were
made for 0 and –10 dBmV
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
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.
DES encryption
Table 38 Cisco uBR900 Series Cable Access Router Data Specifications (continued)
Description Downstream Values Upstream Values