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dmt overhead-framing
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Mode 3 is recommended for use on DMT interfaces adhering to the ANSI T1.413 Issue 2 standard.
Note
Mode 3 is required for flexi line card DMT interfaces.
The number of overhead bytes per frame varies according to the overhead framing mode and the
operating mode, as shown in
Table 3
Overhead Bytes per Frame
Overhead Bytes
T1.413 and G992.1
Framing Mode
Downstream
Mode 0
4
Mode 1
3
Mode 2
2
Mode 3
1
If, during the training sequence, the ATU-R indicates a lower framing structure than that specified by the
ATU-C, the ATU-C falls back to the framing structure number indicated by the ATU-R.
Management requirements drive the determination of overhead, full or reduced. Full overhead provides
more bandwidth to the embedded operations channel (EOC), enabling higher polling rates. However,
reduced overhead provides enough EOC bandwidth to satisfy typical applications.
The dmt overhead-framing command does not cause port retrain when you change the parameter.
Examples
In this example, the command sets the overhead framing mode in the profile named 8xDMT.
DSLAM# configure terminal
DSLAM(config)# dsl-profile 8xDMT
DSLAM(config-dsl-prof)# dmt overhead-framing mode2
Related Commands
Command
show dsl profile
Cisco IOS Release 12.1(6)DA
20
Mode 2—Reduced overhead framing with separate fast and sync bytes in the fast and interleaved
latency buffers respectively.
Mode 3—Reduced overhead framing with merged fast and sync bytes using either the fast or
interleaved latency buffer.
Table
G992.2
Upstream
Downstream
3
N/A
3
N/A
2
N/A
1
1
Description
Display a specific profile, all ports to which the profile is currently attached,
and those port settings.
3.
Upstream
N/A
N/A
N/A
1
Octal-Port DMT ATU-C Line Card
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