dot_null
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join:2004-06-28
Kennesaw, GA
 ·Callcentric
 ·Comcast
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 ·AT&T Southeast
3 edits | [Connectivity] Slow upstream issue in the Atlanta area
Hello everyone,
For about the past week I have had intermittently horribly slow upload speeds - anywhere from less than 100Kbps to 300Kbps, on average when the speed slows down. I have only had the service about 2 months now, I recently switched back to Comcast from AT&T DSL.
Here is an average speedtest I get when the speed issue crops up:
This problem normally happens late in the afternoon and persists until the wee hours of the morning. Today it cropped up at exactly 8:15 PM ET and has persisted until now, and probably will continue for a few hours yet. But for the rest of the day things sail along just great.
I was uploading a rather large file to my webspace and the ETA for completion jumped from 1 hour while things were sailing along, to almost 10 hours when the sudden speed drop happened shortly after 8PM. At the time I was monitoring my pfsense router's live traffic graph page (I guess polled by SNMP?) and the speed dropped rather dramatically from 1Mbps sustained to around 150 kbps. Would've gotten a screen shot of that, but I just came back to the computer as the offending portion showing the massive speed drop cycled off the graph.
Here are the steps I have taken to troubleshoot my end of the connection:
1) I have swapped out the Moto SB-5101 I have (customer owned) with a older SB-5120 I have (also customer owned) to rule out some issue with the modem firmware/hardware/gremlins. This didn't help.
2) I took the router and my internal network topography out of the picture entirely, and connected the modem directly to my laptop (MacBook running OS 10.5.4) via the Ethernet connection. This didn't help either. The slow upstream speeds persisted.
3) I have checked the modem signal levels (also attached to this post) to rule out a signal issue, the levels appear to be fine. Also, the drop was recently replaced from a horrible RG-59 20+ year old drop with a new RG-11 (as best I can tell, it's significantly thicker than RG-6) drop from the pole.
My inside wiring configuration is rather simple. The drop connects to a simple grounding block on the side of my house, and is RG-6 into the house. The coax length is maybe 20 feet long from where it comes from the grounding block into the splitter inside. This splitter is a regular 4 port 7dB loss splitter (the brand name escapes me, but it is a brand name Comcast frequently uses, and a Comcast tech gave me). The line to the modem is less than 15 feet long, and is RG-6.
I contacted Comcast executive care and a tech is coming out Thursday afternoon to look at this issue. Is there anything I should ask him, or anything else I should look at on my end? My inclination is that the issue is somewhere on Comcast's side, but thought I would post the information here for your perusal and analysis.
Thanks!
Modem logs below:
Software Version: SB5120-2.19.0.10-SCM01-NOSH
Hardware Version: 4
MIB Version: II
GUI Version: 1.0
VxWorks Version: 5.4
Time Priority Code Message
2008-09-03 20:57:01 3-Critical R02.0 No Ranging Response received - T3 time-out
2008-09-03 17:19:14 7-Information SNMP: Working in SNMP V1/2c Only NmAccess mode
2008-09-03 17:19:13 7-Information INITIALIZATION COMPLETE - MODEM IS OPERATIONAL
2008-09-03 17:19:13 7-Information B401.0 Authorized
2008-09-03 17:19:12 7-Information PROG: SW Download File name the same as currently run.
2008-09-03 17:19:12 7-Information SEC: Co-Signer CVC from configuration file was verified
2008-09-03 17:19:12 7-Information REGISTRATION COMPLETE - Waiting for Operational status
2008-09-03 17:19:12 7-Information REG: Capability type isn't supported by CMTS
2008-09-03 17:19:12 7-Information Registration file - downloaded
2008-09-03 17:19:10 7-Information Trying to download Configuration file ...
2008-09-03 17:19:10 7-Information Time of day - retrieved
2008-09-03 17:19:09 7-Information DHCP - parameters acquired
2008-09-03 17:19:09 7-Information DHCP: ACK: Setting (*) CM TFTP Boot file: d11_m_sb5120_silver_c01.cm
2008-09-03 17:19:09 7-Information DHCP: Setting CM IP address to: >
2008-09-03 17:19:09 7-Information DHCP: Setting (*) CM Syslog Server address to: 0.0.0.0
2008-09-03 17:19:09 7-Information DHCP: Setting (*) CM Time Server address to: >
2008-09-03 17:19:09 7-Information DHCP: Setting (*) CM Subnet mask to: 255.255.252.0
2008-09-03 17:19:09 7-Information DHCP: Setting (*) CM Gateway address to: >
2008-09-03 17:19:09 7-Information DHCP: OFFER: Setting (*) CM TFTP Boot file: d11_m_sb5120_silver_c01.cm
2008-09-03 17:19:09 7-Information DHCP select: Setting (*) CM TFTP Server address to: >
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daveinpoway
Premium
join:2006-07-03
Poway, CA | Were the modem signal levels you showed (which look fine, by the way) measured during a slow-speed or normal-speed time? Have you noticed any level fluctuations that correspond with the speed changes? |
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spookypuff66
join:2003-11-10
Silverthorne, CO
| My leg is fine. Went on two back to back hikes over the weekend. No problem. The second one was rather long.
I must have had a blood clot. I am taking a low dose of aspirin every morning. My leg hasn't felt this good in over a year.
Asse will have a cateract |
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JahsDisciple
Living my life like it's golden
Premium
join:2007-07-07
Baltimore, MD
·Comcast
1 edit | reply to dot_null
hopefully the tech comes as late as possible. you could try getting the signal levels at a good time and then at a bad time to show him any possible fluctuation. also try at least one other speedtest site. cant think of anything else. please let us know the outcome/resolution.
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"Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity." Rev. Dr. Martin Luther King, Jr. |
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dot_null
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join:2004-06-28
Kennesaw, GA
·Callcentric
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·AT&T Southeast
| reply to daveinpoway
said by daveinpoway  :Were the modem signal levels you showed (which look fine, by the way) measured during a slow-speed or normal-speed time? Have you noticed any level fluctuations that correspond with the speed changes? The signal levels attached to the original post were measured during a slow speed time. I just checked the signal levels (things are fine again, invariably they won't be in a few hours though) and the only change is the downstream power level is 4 dB (-1 dB from the attached levels) and the upstream power level is 44dB (+1 dB from the attached levels).
Thank you for your reply!
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dot_null
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join:2004-06-28
Kennesaw, GA
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·AT&T Southeast
| reply to JahsDisciple
said by JahsDisciple :hopefully the tech comes as late as possible. you could try getting the signal levels at a good time and then at a bad time to show him any possible fluctuation. also try at least one other speedtest site. cant think of anything else. please let us know the outcome/resolution. I agree, the window is from 2-5 PM, and even this probably won't be late enough. The speed didn't slow until about 8:15 PM last night, so he probably won't catch it. I do have speed test logs printed (.csv format) out from speedtest.net, and I will show him those. I have tried other speed test sites but they all yield the same result during slow times, unfortunately - and last night in a real world situation when uploading something to my server in CA via SFTP.
I will mention the fluctuation to him, there were minute fluctuations in the signal levels from last night, but nothing seemingly major.
Thanks for your reply! I will be sure to update with the outcome.
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dot_null
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join:2004-06-28
Kennesaw, GA
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| reply to dot_null
The drop is RIGHT at 8:15-8:16 PM |
Anyway, I think I've nailed down the time that this starts at least. It absolutely starts every night at 8:15-8:16 PM. I purposely scheduled an upload around this time tonight and monitored my router's traffic graph to see how the speed degrades. Well, the chart speaks for itself. Right at 8:16 PM or so the bottom falls out of the speed.
Any thoughts or ideas about what this could be from? Has anyone here had or seen a problem like this, where the upstream speed absolutely goes haywire at a specific time?
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mike12806
Premium
join:2007-08-28
Milton, MA | reply to dot_null
FWIW, could it be bot activity sending out spam??? Have you run antivirus/antispam scans? |
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dot_null
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Kennesaw, GA
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| said by mike12806 :FWIW, could it be bot activity sending out spam??? Have you run antivirus/antispam scans? I have, and even if it was, I should be showing that outgoing activity on my router's live traffic graph. Either way I should also still be using 1 Mbps up sustained.
Thanks for your reply!
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dot_null
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join:2004-06-28
Kennesaw, GA
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| reply to dot_null
Same thing tonight. This time at 8:21 PM the upstream speed started getting very slow.
Assuming this is a Comcast issue (given that I've swapped out the modem and signal levels are great, I have little doubt it is at this point) is there any way this can be escalated to someone locally who can handle the problem further? I assume they're going to want to send out another tech, but quite honestly, it just wastes both of our time if all the tech does is pull signal levels (that are great) and run a speedtest, especially if they come before 8:30 PM, and to my knowledge they don't run that late.
It just seems odd that my upstream speed goes in the dumps anywhere from 8:10-8:30 PM every night, without fail. My patience with Comcast is wearing very very thin.....
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EG
Ho Ho Ho
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join:2006-11-18
Union, NJ | Can we see some traces to say, google.com when the issue is occurring ?
This may be an upstream channel congestion issue. |
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dot_null
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join:2004-06-28
Kennesaw, GA
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| said by EG :Can we see some traces to say, google.com when the issue is occurring ? This may be an upstream channel congestion issue. Sure. Here you go, thanks for your reply! This trace was done directly from my pfsense router.
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EG
Ho Ho Ho
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join:2006-11-18
Union, NJ | Are things bad at the moment because that trace looks fine ? |
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dot_null
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Kennesaw, GA
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1 edit | said by EG :Are things bad at the moment because that trace looks fine ? Yep, the upstream speeds are still pretty bad, and from past experience they will go back to normal sometime after 5AM and mess up again tomorrow evening at around 8:30 PM.
Just did a speedtest and the speed was slightly over 300 Kbps....
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dot_null
Premium
join:2004-06-28
Kennesaw, GA | reply to dot_null
Same thing happened about 8:10 last night....... |
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