Modem lag and latency - poor remote performance

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  • Problem
  • Updated 1 year ago
  • (Edited)
I wanted to share this.

One of the Alpha group members jumped in to help me with challenges I was having with my Cable ISP.  

I was seeing these 200ms lags about ever 1.5 to 2 seconds and it was driving me crazy while remoting to my station.  In fact, it had been happening for some time.  Likely years.

Apparently, there is a modem ChipSet called Puma 6 and there is a bug with the chipset.  
https://www.theregister.co.uk/2016/12/03/intel_puma_chipset_firmware_fix/

This does affect a number of the Aris modems so it seams.  Just to see how bad it is, start poking around the gaming forums.  From their perspective it is so bad, they have created a class action lawsuit (welcome to the US).  

Many cable modes are also possibly affected.

Further testing on my remote with Pingplotter shows a very similar signature.  



The above happens with almost no traffic on my net.  The spikes are long ping times to a server 1 hop away from my station.  You would expect to see a flat graph.

Next, I tested my house.  Another Aris modem and the same issue.  

You might consider looking here is you are hearing some minor breakup while operating remote.  
Mike va3mw

p.s.  Here is a list of modems with Puma 6

  • Arris SB6190
  • Arris TG1672G
  • Arris TM1602
  • Super Hub 3 (Arris TG2492LG)  (commonly, Virgin Media)
  • Hitron CGN3 / CDA / CGNV series modems:
  • Hitron CDA-32372
  • Hitron CDE-32372
  • Hitron CDA3-35
  • Hitron CGNV4
  • Hitron CGNM-3552 (commonly, Rogers)
  • Hitron CGN3 (eg CGN3-ACSMR)
  • Hitron CGNM-2250 (commonly, Shaw)
  • Linksys CM3024
  • Linksys CM3016
  • TP-Link CR7000
  • Netgear AC1750 C6300 AC1900
  • Netgear CM700
  • Telstra Gateway Max (Netgear AC1900 / C6300) (Australia)
  • Cisco DPC3848V
  • Cisco DPC3941B / DPC3941T  (commonly, Comcast Xfinity XB3)
  • Cisco DPC3939
  • Compal CH7465-LG / Arris TG2492LG (commonly, Virgin Media Hub 3)
  • Samsung Home Media Server
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Mike va3mw

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Posted 1 year ago

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Tim Ellam

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Hitron CGNM-2250 (commonly, Shaw)

Thanks Mike. I am getting a new install at our cottage and have emailed Shaw to confirm the modem#

Tim VE6SH
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Danny K5CG

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I'm still rockin' the Arris SB6183! YAY!
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Scott N8UMW

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My Netgear CM 1000 does not have that chipset, thankfully.
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Norm - W7CK

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That article was dated December 2016 and indicated that Intel was working on a software fix.  Seems they would have had something out by now.

Norm - W7CK
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David Decoons wo2x, Elmer

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No fix out yet.

Dave wo2x
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KY6LA - Howard, Elmer

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The 6190 has a firmware update pushed out by SOME ISP’s in April.
Not sure how to verify
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Mike va3mw

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I did a bunch of research and found that some modems had an update, but the fix was questionable.  
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k3Tim

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Translation - don't hold your breathe on a s/w fix.
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David Decoons wo2x, Elmer

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If the problem is the Atom processor on the Puma chipset is overwhelmed at higher bamdwidth I do not believe a software patch will be able to fix it.

Firmware on my TM1602g is December 2015.

Called my ISP today and they have no alternative if you want 200+ MB and telephone service.

Going to call our business rep Monday since we have several cable modems @ 300. MB service at work that use Cisco combo modem/routers for multiple static IP solution.

Dave wo2x
(Edited)
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Scott N8UMW

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Best thing to do is buy your own without that chipset. I had to do some research on that when my previous modem was no longer going to be supported and I wanted to upgrade my speed. The CM 1000 I purchased has been solid and being DOCSIS 3.1 is ready when Comcrap rolls out the gig over cable.
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David Decoons wo2x, Elmer

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my ISP is skipping DOCSIS 3.1and going straight to FTTH.
Unfortunately my ISP only supports modems with the PUMA 6 chipset with their telephone service.

Dave wo2x
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Scott N8UMW

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That's already available at my qth for three bills a month after a grand installation fee and a contract. A full 2Gb though. Smokes Google.
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Mike va3mw

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Be aware. You can have all the bandwidth in the world and still have bad jitter and latency. Make sure you test and verify. I'll take low jitter and low latency over bandwidth on any day for what I am doing.

I have one goal, remote HF operations.

Mike
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Scott N8UMW

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Yes sir. The only time i get jitter is when there is reasonable amount of congestion on at&t. Home network and comcrap pretty quick. I get 360 down and 30 up currently with the CM 1000 modem and R8000 WiFi router. Average ping times on Internet around 12 to 14ms. Rarely ever see any dropped packets on the Flex even when it's been on for days or weeks.