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]

[Andrew-G]

@ PhilHornby

I would agree that your charts show an improvement, but as a personal opinion, and if I'm reading your chart right, it really doesn't look anything like the extent of improvement I want from my awful, horrible, rubbishy, flawed Superhub 3.  Anybody who has done some research on the US forums covering the Puma 6 problems will probably have seen comparative charts for eg Puma 6 alongside equivalent Broadcom cable modems, and they simply don't show any of this high latency nonsense.  If the best that Intel, Arris and Virginmedia can do is a ten or even fifty per cent reduction in the latency spikes, why bother?  At a 50% improvement, the SH3 product will still be performing at a level that a private buyer of such a product would be entitled to demand a refund from the retailer.

And one observation - when I clicked through, the imagehost for your link was displaying some rather spicey advertising around your chart - lucky that I didn't have anybody behind me when I innocently clicked on the chart.

[WillWilson]

Anyone able to advice on OfCom/laws and stuff about 3rd party routers? If i buy a different router because the Hub3 being so bad, do VM have to cover the cost for it at all?

[ShadowOfDeth69]

As far as I know, personally, you can use whatever router you want BUT you need to use Virgin's supplied Hubs. There's no way around that. It's their way or highway...

You MIGHT be able to get a SH2ac and have them activate that instead but that's unlikely to happen unless you get the "right" person taking your call.

[PhilHornby]

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@Andrew-G wrote:

@ PhilHornby

I would agree that your charts show an improvement, but as a personal opinion, and if I'm reading your chart right, it really doesn't look anything like the extent of improvement I want from my awful, horrible, rubbishy, flawed Superhub 3.  

You may have a point. I just found that I still have a comparable graph from the SH/2 Trial. My line speed back in 2013 was probably 30Mbps ... it may even have been 10Mbps..

And the current state of the art :-

HUB3 NTP latency-new firmware

And one observation - when I clicked through, the imagehost for your link was displaying some rather spicey advertising around your chart - lucky that I didn't have anybody behind me when I innocently clicked on the chart.

---

Oops - I wasn't actually aware there was any advertising on that site - I have a 'hosts file'-based ad blocker, so I see nothing.

[WillWilson]

I've got 350Mbps, so I can't even get the 2AC, so no hope? Not even in modem mode?

[Stoddy27]

The trial firmware is not the finished article and I have reported back to VM the issues I am still facing - yes I now get 15-20 ms ping alot more often than I did before but I am still seeing some pings over 500ms. I would hope the trial runs for as long as it takes for the full issue to be resolved. Does anyone know if the firmware sent to VM still shows the high latency issue ? 

Can anyone confirm if the trial firmware would reduce my bandwidth? I seem to be only getting 200mb and 10-12 upload on the 350 package.

[ShadowOfDeth69]

IF you could get them to supply an SH2ac and IF they activate it you will have to downgrade your package to the Vivid 200. Even in modem mode.

It sucks but there ya go.

[Andrew-G]

@WillWilson

"If i buy a different router because the Hub3 being so bad, do VM have to cover the cost for it at all?"

In summary, I'm not sure you can, and no, respectively.

Because DOCSIS 3 (and indeed 3.1) are not proprietary VM standards, there's no technical reason that I know of why we couldn't buy and use a compatible modem that isn't contaminated by Intel's poor quality chipsets.  If you do a search on Amazon.com you'll find a range of options for US cable customers for quite modest sums - a few are even imported to the UK, but I don't know who they sell them to.  However, as far as I can see Virginmedia don't give us the choice, and having procured a poor quality product, that still isn't fixed, they just continue to hand them out and say "your problem sunshine".  Absent any real competition in broadband, we take it or leave it, and because the modem is VM's property, any legal claim, would be about the overall quality of service, not the performance of the modem per se.  The Terms and Conditions specifically avoid making any guarantees about performance, so I don't think you've got much redress, although I'm sure you couldn't be held to VM's contract length if you opted to leave.  The whole SH3 debacle is now a year old, with no sign of any resolution, and my hopes are not high that we will see a fully effective fix.  

I was thinking about starting a new thread, specifically asking Virginmedia why we can't throw our SH3s in the bin where they belong (or give them back to VM to place you know where), and buy our own compatible DOCSIS 3 modems (and I'd want a quid a month discount on my broadband bill).  I'm sure they'll never pay for it, but does anybody round here know more about whether there is any prospect of using a third party modem on Virginmedia?  I'd buy my own to rid my house of the SH3 abomination.

[WillWilson]

I didn't mean directly get a docsis 3.0/.1 router, as the VM Hub3 will always be needed because of modem mode, but to do the rest of the 'routing' I agree about their response to this, has been awful, and too many people have waiting too long for fix

[DarkBahamut]

The 'routing' part of the Hub 3 isn't the problem, the modem part is. Using a 3rd party router has many benefits, but it won't fix your latency.

And no, VM won't pay you to buy one.