Slow throughput on 7.1 Mb/s line
trp2525
Enthusiast - Level 2

I ran some speed tests today to check my 7.1 Mb/s line as I do occasionally and I found out that even though I was syncing with the CO at 7661 my download speed tests are only coming back in the 1.1 to 2.0 range. Some were actually well below 1.0 today. Previously I was routinely getting speed tests in the 6.5 to 6.6 range on this line, which has been provisioned at this speed for 3 and a half years. My current transceiver stats are as follows:

Transceiver Statistics

Transceiver Revision: 7.2.3.0
Vendor ID Code: 4
Line Mode: ADSL2+ Mode
Data Path: Interleaved

Transceiver Information Downstream Path Upstream Path
DSL Speed (Kbits/Sec) 7661 863
Margin (dB) 6.0 14.0
Line Attenuation (dB) 45.0 25.0
Transmit Power (dBm) 19.4 12.1

I know that my downstream margin is low at 6.0 but this is a VERY STABLE line that will go weeks without losing sync even with that low margin. The ADSL2+ is really giving me some help at my attenuation.

So far today for troubleshooting I tried replacing my 7-year-old Westell 327W B90 modem with a brand-new Westell 327W D90 modem that I had stored away in a box. There was no difference in the speed tests when I used either modem. They were both running the 4.04.03 firmware which is the latest for the Westell 327W modems.

I also tried uninstalling and reinstalling my NIC card as I'm connected via ethernet cable to my modem. That made no difference in my speed tests either.

I did run a Network Diagnostic Tool at M-Lab with the following results:

Upload speed
0.73 Mb/s
Download speed
1.1 Mb/s
Network latency: 5.8e+2 msec round trip time

Jitter: 8.1e+2 msec

Your system: Windows XP version 5.1
Java version: 1.7.0_04 (x86)

TCP receive window: 255552 current, 255552 maximum
9.62464E-4 packets lost during test
Round trip time: 70 msec (minimum), 875 msec (maximum), 580.12 msec (average)
Jitter: 805 msec
0 seconds spend waiting following a timeout
TCP time-out counter: 935
130 selective acknowledgement packets received

No duplex mismatch condition was detected.
The test did not detect a cable fault.
Network congestion may be limiting the connection.
No network address translation appliance was detected.

0.9756% of the time was not spent in a receiver limited or sender limited state.
0.0% of the time the connection is limited by the client machine's receive buffer.
Optimal receive buffer: 261685248 bytes
0 duplicate ACKs set

So it looks like I have a network congestion issue going on. I'm wondering if it has to do with the router that I'm on or if my local CO (Fall River, MA) is having a more widespread problem. I'm thinking of keeping an eye on it for the next few days and see if it gets back to normal on its own. I'm very hesitant to contact Verizon as the last time I did a few years ago they cut my speed down to 5 from 7.1 and took away my ADSL2+. I had to talk to executive customer relations to get them back and it was not an easy task!

Does anyone have any suggestions or opinions about my situation?

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Re: Slow throughput on 7.1 Mb/s line
smith6612
Community Leader
Community Leader

Is this issue an all-day, all night occurrence or is it something that happens mainly during prime time in the evening hours? That's key to what the problem may be.

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Re: Slow throughput on 7.1 Mb/s line
trp2525
Enthusiast - Level 2

I've been running speed tests at various times of the day and night over the last two days and this is definitely a problem only during peak-use evening hours.  During off-peak hours I am getting speed tests consistently in the range of 6.5 to 6.6 which is right where I should be on a 7.1 line provision when you consider the overhead.  During peak hours my speed tests are running in the range of 1.0 to 1.5 but one test was at 0.68 which is slower than my upload speed.  My upload speed tests are always perfect and are running at 0.71 to 0.73 which is where I should be on a 768 upload line.

I'm thinking that I must be on a congested edge router/circuit.  That would explain the congestion only during peak-use hours and my getting perfect speed test results at all other times.  I would like to request that I be moved to another edge router/circuit but I am concerned if I go through the normal Verizon channels that they will downgrade my speed from 7.1 and/or take away my ADSL2+ provisioning in the process of moving me.  This already happened once in the past when I put in a work order to have a homerun installed at my home.  After running some routine line checks they downgraded me to a speed of 5 and took away my ADSL2+ at the CO.  They wouldn't budge to put me back to my original provisioning until I got executive customer relations involved.

All has been fine on this line at 7.1 provisioning until this recent slowdown issue.  I've had this 7.1/768 package since it was first offered in my area 3 and 1/2 years ago.  I was one of the very first customers in my area to get it.  I'm wondering if they have oversold their bandwidth at the CO in the meantime.  Those customers currently on the "enhanced" DSL plan and close enough to the CO (does not include me) could be getting 10 or 15 line provisioning from Verizon and that could possibly be causing the prime-time slowdowns.  Those 10 and 15 speed packages did not exist when I first got my 7.1 service.

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Re: Slow throughput on 7.1 Mb/s line
smith6612
Community Leader
Community Leader

Sounds about right. They might have also retired some older equipment you or others were on too, or moved the network around a bit and there's further load on equipment that didn't need it. The COs themselves typically don't have issues as far as the backhaul goes, so I doubt that is the case, else even the business customers coming out of the CO would have issues at night when some businesses tend to run their after-hours tasks. Considering they pay for a higher level of service, they should most certainly notice that and complain.

I can get you to someone who can fix this issue, however they are out for a few weeks due to some extending circumstances. I'll shoot you a PM to reach out to them to have this problem resolved, but anticipate anything being done to the line to take some time until he's able to take a look for you. He'll get you fixed up though as he does have the ablity to see where congestion is and works when it happens to occur the most.

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Re: Slow throughput on 7.1 Mb/s line
trp2525
Enthusiast - Level 2

PROBLEM RESOLVED

I contacted the Verizon Direct Forum at DSL Reports and received a telephone call from someone at the executive customer relations department at Verizon. He was able to have someone from my local Central Office who does network management/DSL provisioning contact me directly by phone. I was changed over to a "less congested" router right while I was on the phone with this person from my local CO. My ADSL2+ and 7.1 speed package were left intact on my line during the change to a new router. All seems to be well as I am now getting actual speed throughput of 6.5 to 6.6 even during peak evening hours!