  More Fiber Premium,MVM join:2005-09-26 West Chester, PA
·Bay Area Internet ..
| reply to N O Y B Re: Nighttime slowdown again
said by N O Y B :But in speed tests aren't the upload and download performed at different times? So one should not have any impact on the other? Yes, the download and upload tests are performed separately. That is not what deblin was talking about.
For each block that is transferred (up or down), there is an ACK that flows in the opposite direction. If there is congestion in the direction the ACKs are flowing, the ACKs are queued and not sent as quickly as possible. This throttles the sender until the ACK is received. There is more involved, but that's the general idea.
What deblin was trying to point out was that since the OP's upstream tests were good, downstream ACKs are not being delayed, and therefore downstream congestion is not an issue. |
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  N O Y B St. John 3.16
join:2005-12-15 Forest Grove, OR
| said by More Fiber :said by N O Y B : ...since the OP's upstream tests were good, downstream ACKs are not being delayed, and therefore downstream congestion is not an issue. The downstream ACKs require/consume very little bandwidth. Far less than the downstream throughput the OPer is getting, so of course down stream ACKs are unlikely to be impacted enough to cause upstream slowness.
I'm inclined to think maybe the OPer has something running unaware. Or maybe if the OPer has FiOS TV the STB is doing something weird. Also if this is with WiFi a whole host of things could be in play.
Another thing that is interesting is the 0 ms ping in one test and then 10 ms ping in the next.
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