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Author Topic: FTTC attainable values?  (Read 295 times)


  • Kitizen
  • ****
  • Posts: 2489
FTTC attainable values?
« on: May 15, 2017, 10:22:59 AM »

While I was running not interleaved my attainable values were around 61000kbps but since being put on interleaved last Saturday it has increased substantially to around 70000kbps. Not sure I understand why, can anyone explain why the very significant increase?

ISP:TalkTalk Connection:FTTC Cab:ECI Router:ZyXEL VMG8924-B10A


  • Kitizen
  • ****
  • Posts: 1261
Re: FTTC attainable values?
« Reply #1 on: May 15, 2017, 04:20:10 PM »

It's because the max attainable value can be calculated using different parameters than what the line will actually have to use.

The "basic" max attainable rate method in G.993.2 left various aspects undefined, and I expect most manufacturers filled in the blanks to give the highest possible value.

Essentially, the max attainable value is calculated using interleaving parameters (such as depth, block size, amount of FEC) chosen to give maximum bandwidth. It has to stay within the max delay parameter, but it does not need to meet the min INP parameter.

For the actual speed, the interleaving parameters will have to be chosen to meet the min INP level specified.


  • Member
  • **
  • Posts: 24
Re: FTTC attainable values?
« Reply #2 on: May 15, 2017, 07:41:06 PM »

Or to put it more simply it calculates a theoretical value that is not actually achievable in practice. :)