Hub 3 / Compal CH7465-LG (TG2492LG) and CGNV4 Latency Cause

[Datalink]

Good Day Ladies and Gentlemen,

Greetings from the other side of the pond, so to speak.  Over the last few weeks I've been perusing various user forums across North America and Europe for issues related to Intel Puma 6 modem latency.  Of those forums, your Hub 3 stands out as yet another Puma 6 based modem where users see continuous latency no matter what site is used or what online game is played. Considering all of the problems that are on the go, the following information should be of interest to all Hub 3, Compal CH7465-LG and Hitron CGNV4 modem users.  There is much more to post regarding this, so this is a start, to alert VM users as to the real cause of the latency and hopefully engage the VM engineering staff, via the forum staff, with Arris.  I am surprised to see that there has been no mention on this board of users from other ISPs who are suffering the exact same issues with their modems, so, this may come as a surprise to some, and possibly old news to others.

So, the short story ........

The Hub 3 / Compal CH7465-LG (TG2492LG) & Hiton CGNV4 modems are Intel Puma 6 / 6 Media Gateway (MG) based modems.  These modems exhibit high latency to the modem and high latency thru the modem.  The latency affects all IPV4 and IPV6 protocols, so it will be seen on every internet application and game.  The basic cause is the processing of the data packets thru a CPU software based process instead of thru the hardware processor / accelerator.  It appears that a higher priority task runs periodically, causing the packet processing to halt, and then resume.  This is observed as latency in applications and in ping tests to the modem and beyond.  For the last several weeks, Hitron, along with Intel and Rogers Communications in Canada have been addressing the latency issue within the Hitron CGNxxx series modems.  To date, only the IPV4 ICMP latency has been resolved.  Although this is only one protocol, it does show that a Puma 6MG modem is capable of using the hardware processor / accelerator with good results.  Currently Rogers is waiting for further firmware updates from Hitron which should include an expanded list of resolved protocol latency issues.  For Arris modems, "Netdog" an Arris engineer indicated last week that Arris was onboard to address the issue for the Arris SB6190 modem.  That should be considered as good news for any Arris modem (read Hub 3) user as Arris should be able to port those changes over to other Puma 6/6MG modems fairly quickly.  This is not a trivial exercise and will probably take several weeks to accomplish.  Note that there is no guarantee at this point that it is possible to shift all packet processing to the hardware processor / accelerator without suffering from any packet loss side effects.  Time will tell if all of the technical issues can be resolved with the current hardware included in the Puma 6/6MG chipset.  Last night, Netdog loaded beta firmware on selected test modems on the Comcast Communications network.  As this was only done last night, it's too soon to tell what this version resolves and if it was successful or not.  Netdog has contacts with staff at Comcast, Rogers, Charter and Cox Communications to fan out beta versions and modifications for testing.  I'd say its time to add Virgin Media and/or Liberty Global to that group as well.

Recent activity:

Approx three weeks ago a DSLReports user, xymox1 started a thread where he reported high latency to an Arris SB6190 and illustrated that with numerous MultiPing plots.  This is the same latency that I and other users with Rogers communications have been dealing with for months so it came as no surprise.  As well as reporting via that thread, xymox1 took it upon himself to email several staff members at Arris, Intel, Cablelabs and others.  The result of that campaign was Netdog's announcement, last week, that Arris was fully engaged at resolving the issue.  That has led to last nights release of beta firmware, although as I indicated its too early to determine what the beta firmware resolves, if anything.

The original thread that xymox1 started is here:

https://www.dslreports.com/forum/r31079834-ALL-SB6190-is-a-terrible-modem-Intel-Puma-6-MaxLinear-mis...

Yesterday, DSLReports issued a news story covering the thread:

https://www.dslreports.com/shownews/The-Arris-SB6190-Modem-Puma-6-Chipset-Have-Some-Major-Issues-138...

Today, Arris responded:

https://www.dslreports.com/shownews/Arris-Tells-us-Its-Working-With-Intel-on-SB6190-Puma6-Problems-1...

That response was also picked by Multichannel.com

http://www.multichannel.com/news/distribution/intel-arris-working-firmware-fix-sb6190-modem/409379

This is more news likely to appear in the next few days as additional tech and news staff pick up on this issue.

Hub 3 observations:

Like many others using a Puma 6/6MG modem, Hub 3 users are experiencing latency when they ping the modem, or ping a target outside of the home, game online or use low latency applications.  The common misconception is that this is Buffer Bloat. It's not. Its most likely a case of the packet processing stopping while the CPU processes a higher priority task.  The packet processing is done via the CPU no matter what mode the modem is operating in, modem mode or router mode and no matter what IPV4 or IPV6 protocol is used.  Normally, the latency is just that, latency.  The exception are UDP packets. In this case there is latency and packet loss.  The result of that is delayed and failed DNS lookups, and poor game performance for games that use UDP for player/server comms or player/player comms.

Can this be fixed?

So far, it appears that the answer is yes.  Rogers Communications issued beta firmware to a small group of test modems in October.  This version shifted the IPV4 ICMP processing from the CPU to the hardware processor / accelerator, resulting in greatly improved performance in ping latency.  At the present time we are waiting for the next version firmware which should shift other protocols over to the hardware processor / accelerator.  That can be seen in the following post:

http://communityforums.rogers.com/t5/forums/forumtopicpage/board-id/Getting_connected/message-id/369...

The details and results of last nights beta release to the Comcast group have yet to be seen.

At this point there is enough reading to keep most staff and users busy.  My intention is to post some of the history leading up to this point and instructions on how to detect the latency and packet loss.  This is not thru the use of a BQM.  I had hoped to post this all at once but events are moving much faster than I had thought they would.  For now this should suffice to get the ball rolling.

Below is a link to a post with a couple of HrPing plots from my 32 channel modem to the connected CMTS.  This shows the latency that is observed and reflects what others have posted in this forum using Pingplotter and HrPing.

https://www.dslreports.com/forum/r31106550-

HrPing is one of the freebie applications that can be used to monitor the latency to and thru the modem. 

Pingplots with Pingplotter which show the latency from my modem to the CMTS can be found in the first two to three rows of my online image library at Rogers Communications, located below.  They are essentially what the BQM would look like if you were able to zoom into the plot to the point where you could see the individual ping spikes.  Those ping spikes are common to Puma 6 and Puma 6MG modems.

http://communityforums.rogers.com/t5/media/gallerypage/user-id/829158

 [MOD EDIT: Subject heading changed to assist community]

[deviousiphone]

No I do agree, but to be honest people with congestion would of been used to hopeless refresh dates, and extra channels would only help to a limited degree, personally I would of told Arris to take your broken gear back, left things how they are currently and got a new modem supplier in the meantime, instead of promoting a gamer service that is questionable at best, but then debating what should of happened won't change what has.

[Pasbags]

That BT connection is beautiful. 

[MUD_Wizard]

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@deviousiphone wrote:
No I do agree, but to be honest people with congestion would of been used to hopeless refresh dates, and extra channels would only help to a limited degree,

Extra downstream channels being added to a line card at the CMTS only helps a little at the moment because most people are still on 8 channel modems or less. One person on a node/hub limited to 8 channels can max out 200Mb of the available 400Mb of total bandwidth. That's half.

Much harder for an individual to max out 1200Mb of bandwidth (24 downstream channels). Especially as tiers only go up to 300Mb right now. Very few sites on the internet support 300Mb of continuous bandwidth. 

So the more people you have on 24 channels the better for everybody. The problem is that takes time.

When higher tiers are added they will be offloaded to OFDM on Docsis 3.1. Freeing up bandwidth on the remaining SC-QAM channels (the current Docsis 3.0 channels). So things should improve.

It's like arguing against opening up additional lanes on the motorway.

personally I would of told Arris to take your broken gear back, left things how they are currently and got a new modem supplier in the meantime,

Supplier lead times are well over a year, so way too late by the time they tested the gear and most of the available hubs for cable at the time were Puma 6 anyway. Comcast have the same problem but are further ahead with Docsis 3.1 rollout.

instead of promoting a gamer service that is questionable at best, but then debating what should of happened won't change what has.

Indeed. Like I say it could have been handled way better. 

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[tommey]

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@MUD_Wizard wrote:

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@deviousiphone wrote:

instead of promoting a gamer service that is questionable at best, but then debating what should of happened won't change what has.

Indeed. Like I say it could have been handled way better. 

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I do wonder how many more times in my life time will I hear someone say "it could have been handled way better" when referring to Virgin Media....

I find it best to expect nothing from Virgin Media that way I never get disappointed.

[MUD_Wizard]

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@tommey wrote:

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@MUD_Wizard wrote:

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@deviousiphone wrote:

instead of promoting a gamer service that is questionable at best, but then debating what should of happened won't change what has.

Indeed. Like I say it could have been handled way better.  

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I do wonder how many more times in my life time will I hear someone say "it could have been handled way better" when referring to Virgin Media....

That's the polite version, as the other version would be full of expletives.

I find it best to expect nothing from Virgin Media that way I never get disappointed.

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Yes, I always do too.

[rio_w]

I'd like to terminate my plan, want to go to fibre broadband, but I don't want to pay early termination fee or penalty.

[mbulliva]

You can always wait until you receive a price increase letter, once you receive one of these you can leave without penalty.  We had one of these last year in the September/October/November time-frame, so maybe there will be one this year around the same time.

Who knows, maybe the Puma 6 issue might have had a fix by then...

[tommey]

@rio_w

Do you have high utilisation and a fault code? if you do then give retention's a call and they should be able to free you from any of the remaining contract without penalty, if you don't then it will be harder as there is no fault code for the puma 6 issue (that I am aware of) even so give retention's a call and just be nice and see if they can do anything for you,

Good Luck

[Tengenstein]

Yesterday Evening VM  text me saying they had sorted the issue affecting my local cabinet, so no longer running on only 8 but up to 12 lines. Unfortunately as expected this means the Hub 3.0 issue is felt in full force. just look at the packet loss for last night after switching it back into router mode:

[

[MUD_Wizard]

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@Tengenstein wrote:

Yesterday Evening VM  text me saying they had sorted the issue affecting my local cabinet, so no longer running on only 8 but up to 12 lines. Unfortunately as expected this means the Hub 3.0 issue is felt in full force. just look at the packet loss for last night after switching it back into router mode:

[

That's a really nice graph for a Hub 3 once it locked the channels.

It's just taking a while to lock them and producing T4 timeouts, which is the red lines of packet loss. Just a network issue, nothing more.

The increased latency is because it's only on one upstream channel during that time.