Cisco Octal-Port DMT ATU-C Line Card Bedienungsanleitung PDF herunterladen (Seite 8)

Cisco 6160 DSLAM Overview 183

dmt-margin is equal to the upstream and downstream SNR margins in decibels. Values must be

nonnegative integers. The range is from 0 to 127 dB.

NOTE Research has shown that the optimum margins for DMT service are 6 dB downstream and 6 dB

upstream.

In Example 8-2, the command sets the DMT SNR margins of the ccnp proﬁle to 6 dB upstream

and 3 dB downstream.

Setting Check Bytes

Check bytes are also called FEC bytes. They are added to the user data stream to improve error

correction, but they slow performance. To set upstream and downstream check bytes, use the

following command:

dmt check-bytes interleaved downstream

bytes

upstream

bytes

bytes values can be 0, 2, 4, 6, 8, 10, 12, 14, and 16. The default is 16 in each direction.

In Example 8-3, the command sets the interleaved check bytes for the ccnp proﬁle to 6 upstream

and 12 downstream.

Setting Interleaving Delay

To set the interleaving delay parameter, use this command:

dmt interleaving-delay downstream

delay-in-µsecs

upstream

delay-in-µsecs

delay-in-

secs speciﬁes the interleaving delay in microseconds. The default value is

16000 microseconds in each direction. Allowable values are 0, 500, 1000, 2000, 4000, 8000,

and 16000 microseconds.

In Example 8-4, the command sets the interleaving delay of the ccnp proﬁle to 2000 microseconds

downstream and 4000 microseconds upstream.

Example 8-2 Setting the Margin

lab-6160#configure terminal

lab-6160(config)#dsl-profile ccnp

lab-6160(config-dsl-prof)#dmt margin downstream 3 upstream 6

Example 8-3 Setting the Check Bytes

lab-6160#configure terminal

lab-6160(config)#dsl-profile ccnp

lab-6160(config-dsl-prof)#dmt check-bytes interleaved

downstream 12 upstream 6

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Cisco Octal-Port DMT ATU-C Line Card Bedienungsanleitung Seite 8