Chapter 4 Troubleshooting the System
Managing Cable Modems on the HFC Network
Caution Only a trained CMTS administrator should adjust these values.
To configure the dynamic map advance algorithm, use the following command in cable interface configuration mode.
Table | Instructions to Configure the Dynamic Map Advance Algorithm |
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Command |
| Purpose |
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Specify a value to enhance the upstream | ||
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| throughput from a cable modem connected to the |
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| Cisco uBR7200 series. The <n> parameter |
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| provides the safety factor for the dynamic map |
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| advance algorithm. This parameter is specified in |
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| usecs and controls the amount of extra lookahead |
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| time in MAPs to account for inaccuracies of the |
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| measurement system and software latencies. The |
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| default value is 1000 usecs. |
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| You can vary this between 500 to 1500 usecs. This |
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| parameter is a delta value added to the dynamic |
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| larger safety factors increases the run time |
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| lookahead in MAPs, but reduces the upstream |
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| performance. |
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| Use the static keyword for the map advance |
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| command. The Cisco uBR7200 series will use a |
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| fixed lookahead time in MAPs, regardless of the |
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| real propagation delay of the farthest cable modem |
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| on the network. This fixed lookahead time is |
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| computed based on the worst case parameters such |
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| as farthest DOCSIS propagation delay for the |
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| CMs. |
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Caution Cisco recommends if you are adjusting the dynamic map advance algorithm that you do not reduce the safety factor below the default value of 1000 usecs in a production network until you are confident that the reduced safety factor suffices for your deployment. The default value is chosen to be a safe operating point for the algorithm.
Configure Per Modem Filters
You can configure the Cisco uBR7200 series to filter incoming packets from individual hosts or cable modems based on the source Media Access Controller (MAC) or Internet Protocol (IP) address. Definition of filters follows standard Cisco IOS configuration practices for access lists and groups.
Note Configuring per modem or host filters is supported in Cisco IOS Release 12.0(5)T1 or higher, as well as in Cisco IOS Release 12.0(6)SC or higher.
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
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