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]

[CJS23]

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@Boygroucho wrote:

"I was a big complainer but to be honest the latest trial firmware looks pretty rosy compared to before!"

Its interesting that as expectations lower, how much easier it is to celebrate mediocrity.

---

To be fair, the quote at the top does not imply to me that mediocrity has been accepted, just that the latest Firmware has empirically and evidentially resolved the majority of the issues they were experiencing. (Apologies, however, if I've misunderstood what you were actually saying, btw)

That's all I'm after too, to be honest. I just want the same performance from the "updated" Hub 3.0 as I have always had from my trusty SH2AC.

[Germ]

So 9.1.116V is the new firmware?

[Andrew-G]

No, 9.1.116V is the previous "general issue" firmware with all its faults. 

Because Virgin Media management (to judge by what we see) live in abject fear of communicating with customers, no customer actually knows as a matter of proven fact* what the latest general issue firmware is. Most of us believe that the latest firmware is 9.1.116.603 that appears to be being deployed to users on 350 Mbps connections, but absent any official word it is possible that's an extended trial.  

* When I say "proven fact", I don't mean the mutterings of an installation technician, a statement by the APPALLING offshore call centre, or even promises from UK second line support or retentions, I mean a proper official statement about what is the latest firmware, what the company they believe they've fixed, whether there is any further firmware development going on for the other broken bits of the Hub 3 software, and what the roll out plan is.  This being Vermin Media, I'm expecting that statement on the 12th of Never.

[Germ]

When gaming everything was relatively smooth for a day and a half but went back to normal that's why I was asking. I'm starting to think that there's just to many people on VM where I live that's making it worse. It still wasn't close to perfect but it was a major difference from what i have experienced. 

[CJS23]

Aside from those on 350mbps and the Triallists, does anyone on 200mbps have the .603 FW does anyone know?

[Datalink]

@CJS23's comments are rather interesting. As far as I'm aware, no one, and no company, including Intel has publically proven that the latency issues have been resolved for all protocols, ie: ICMP, TCP/IP and UDP, and the various offshoots of those protocols. If thats the case, I'd love to see the test results that prove that this issue has finally been resolved, some 6 years after Intel initially developed the Puma 6 chipset.

"4. Intel argues that “[i]f Intel’s internal improvement efforts
were to become public, third-party competitors would be able to use Intel’s own internal analysis,
which they ordinarily would not be able to access, to disparage Intel’s Puma 6 chipset and spread
fear, uncertainty, and doubt in the marketplace relating to the Puma 6 chipset and latency issues
that Intel identified and already resolved.”

Show me the proof !  Its pretty easy to disparage a product that has shown terrible performance since day one, when the design company itself hasn't shown any test data that refutes the observed problems.  Intel could easy put this behind them by releasing independent verified test results.  Until that happens, there will always be doubt about the Puma 6 performance, and that doubt will carry on to Puma 7 modems, which is unfortunate.

[philjohn]

Yeah, when you're in the middle of a class action lawsuit and there is a lot of information out there there will be a good reason that legal is overriding PR - Judges tend to look down on trying to make an end-run around the process by releasing things to the press.

Anyway, there's empirical data that typical UDP flows or around 1Mbps are free from jitter spikes for extended periods of time, whereas before they weren't. Testing UDP at much more than that isn't particularly useful as you'll get more packet loss (and that's the same with any connection - UDP packets aren't guaranteed to be received, much less in order - they are fire and forget).

I doubt any game is using more than 1Mbps anyway, and VOIP uses considerably less than that.

[CJS23]

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@philjohn wrote:

Yeah, when you're in the middle of a class action lawsuit and there is a lot of information out there there will be a good reason that legal is overriding PR - Judges tend to look down on trying to make an end-run around the process by releasing things to the press.

Anyway, there's empirical data that typical UDP flows or around 1Mbps are free from jitter spikes for extended periods of time, whereas before they weren't. Testing UDP at much more than that isn't particularly useful as you'll get more packet loss (and that's the same with any connection - UDP packets aren't guaranteed to be received, much less in order - they are fire and forget).

I doubt any game is using more than 1Mbps anyway, and VOIP uses considerably less than that.

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That pretty much sums up my view also. Anyone any ideas on my firmware question? I'm having a nightmare after just 2 days and am SO tempted to go back to the SH2AC which I retained with VM's permission. This means I would be turning down the possibility of 350mbps though as they will flat out refuse to provision on the SH2AC 

From my public FB Post to VM here 

 [MOD EDIT: Personal and private information has been removed from this post. Please do not post personal or private information in your public posts. Please review the Forum Guidelines]

[philjohn]

You have three options, go back to the SH2, keep the SH3 and Vivid 200 or upgrade to Vivid 350 for an extra £5 a month and be in with a good chance of getting the new firmware.

Remember, you can always downgrade, with 30 days notice, back to Vivid 200 and start using your SH2 again if you don't get the updated firmware, or if the update doesn't fix your problems.

[Andrew-G]

CJS23: "This means I would be turning down the possibility of 350mbps though as they will flat out refuse to provision on the SH2AC "

If they re-enable the SH2ac, chances are they'd do that remotely and you'd still have the Hub 3.  If at some future date you wanted and were able to order 350, by that time you should have a definitive view on performance reported by other users with the 603 firmware, VM would be able to reactivate the Hub 3 that you'd have at the back of a cupboard, so I don't think you're turning down the possibility of anything.