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North American Network Operators Group

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Re: DSL and/or Routing Problems

  • From: Joshua Coombs
  • Date: Tue Mar 30 15:35:49 2004

> DSL BENCHMARK:
> ==============
>                 ATU-R (DS)                      ATU-C (US)
> Capacity Used:   72%                             21%
>
>                  Interleave             Fast    Interleave
Fast
> Speed (kbps):             0              960             0
256
> Reed-Solomon EC:          0                0             0
0
> CRC Errors:               0                0             0
0
> Header Errors:            0                0             0
0
> Bit Errors:               0                0
> BER Valid sec:            0                0
> BER Invalid sec:          0                0
>
>
>
> DSL NOW:
> ========
>                 ATU-R (DS)                      ATU-C (US)
> Capacity Used:   94%                             63%
>
>                  Interleave             Fast    Interleave
Fast
> Speed (kbps):           736                0           256
0
> Reed-Solomon EC:         99                0             4
0
> CRC Errors:               4                0             1
0
> Header Errors:            3                0             0
0
> Bit Errors:               0                0
> BER Valid sec:            0                0
> BER Invalid sec:          0                0

You've gone from fast path to interleaved.  Interleaved can inject
up to 64ms of latency, in each direction, ontop of the normal line
latency.  (IE say 12ms loop time, interleaved can bump that up to
140ms latency.)  Interleaved is used to trade latency for line
stability.  I'm not sure of the specifics on that however.
Basically, you set your latency tolerance on the dslam, up to 64ms
for up and downstream, and dependant on line conditions, your
latency will vary between base loop latency and the max allowed by
your tolerance.  On a good line, you won't see any latency injected,
a poor line will run right up to the tolerance and still retrain due
to errors.

You need to ask the telco why they've changed you from fast path,
and request that you get put back to a fast path config.  You MAY be
able to restrict your dsl modem to training fast path only if they
have your line set to auto for signaling.

Joshua Coombs






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