Chapter 4 Troubleshooting the System
Managing Cable Modems on the HFC Network
Although the binary exponential backoff algorithm operates in a distributed fashion at different CMs, the CMTS provides centralized control for the backoff algorithm. To achieve this, it remotely monitors traffic
The following cable interface commands are available to configure the dynamic contention algorithms:
[no] cable
[no] cable upstream <port num>
[no] cable upstream <port num>
Tips System defaults are to have dynamic ranging interval enabled, dynamic ranging backoff enabled, and fixed data backoffs for each upstream of a cable interface.
The default automatic insertion interval setting enables the Cisco automatic initial ranging period algorithm where lower and upper default values of 50 msecs and 2 secs are used. The default automatic
To deviate from system defaults, use one of the following commands in cable interface configuration mode.
Table | Instructions to Modify Dynamic Contention Algorithm Defaults |
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Command |
| Purpose |
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| Disable or enable the dynamic ranging interval | |
automatic |
| algorithm. If lower and upper bounds for varying the |
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| period are not specified, the system uses default values |
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| of 50 msecs and 2 secs respectively. |
Set the lower bound on the initial ranging period for | ||
| the auto ranging algorithm. | |
| Set the upper bound on initial ranging period for the | |
auto ranging algorithm. | ||
Reset fixed initial ranging period to default value of | ||
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| 500 msecs. Also invokes fixed initial ranging |
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| algorithm. |
| Enabled fixed initial ranging period algorithm with | |
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| specified fixed period (msecs). |
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Configure the Dynamic Map Advance Algorithm
A CMTS administrator can enhance the upstream throughput from a cable modem connected to the Cisco uBR7200 series. The system employs a new algorithm that auto tunes the lookahead time in MAPs based on several input parameters for the corresponding upstream channel. The use of dynamic/optimal lookahead time in MAPs significantly improves the
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
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