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cable upstream docsis-mode
The DOCSIS 2.0 specification allows an upstream to be configured in one of the following three modes:
A-TDMA only mode—Upstreams support only cable modems that register using A-TDMA
•
modulation profiles. The CMTS does not allow DOCSIS 1.0 and DOCSIS 1.1 cable modems to
register and come online these upstreams. The Cisco uBR-MC5X20S/U, Cisco uBR-MC16U/X, and
Cisco uBR-MC28U/X cards also support 6,400,000 Hz (5,120,000 symbols/sec) when operating in
DOCSIS 2.0 (A-TDMA-only) mode.
Changing the DOCSIS mode to A-TDMA only mode also automatically changes the symbol rate to
5.12 megasymbols per second and the channel width to 6.4 MHz. Dynamic upstream modulation is
also automatically disabled.
In addition, the following are required to support the DOCSIS 2.0 A-TDMA features:
•
TDMA-only mode—Upstreams support only cable modems that register using TDMA modulation
profiles. DOCSIS 2.0 cable modems can register on these upstreams only by using a
DOCSIS 1.0/DOCSIS 1.1 modulation profile (which typically would happen only when a
DOCSIS 2.0 cable modem cannot find an A-TDMA channel in its DOCSIS domain).
Changing the DOCSIS mode to TDMA-only mode also automatically changes the symbol rate to
1.28 megasymbols per second and the channel width to 1.6 MHz. Dynamic upstream modulation is
also automatically disabled.
Mixed mode—Upstreams support both DOCSIS 1.0/DOCSIS 1.1 cable modems using TDMA
•
modulation profiles and DOCSIS 2.0 cable modems using A-TDMA modulation profiles. (The
maximum channel width in mixed mode is 3.2 MHz.)
Changing the DOCSIS mode to mixed mode also automatically changes the symbol rate to
1.28 megasymbols per second and the channel width to 1.6 MHz. Dynamic upstream modulation is
also automatically disabled.
Note
Cisco Broadband Cable Command Reference Guide
2-302
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Cable modems must be DOCSIS 2.0 capable.
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The DOCSIS configuration file for the cable modem must either omit the DOCSIS 2.0 Enable
field (TLV 39), or it must set TLV 39 to 1 (enable). If you set TLV 39 to 0 (disable), a
DOCSIS 2.0 CM uses the TDMA mode.
The upstream must be configured for either A-TDMA-only or mixed TDMA/A-TDMA mode.
–
Mixed mode upstreams do not support the 6.4 MHz channel width.
Chapter 2
Cisco CMTS Configuration Commands
OL-1581-08
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