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]

[Connect123]

Just wondering out of curiosity that is the bottom still capable of giving a good online gaming experience even though it's for the virgin business lines? My partner might be changing the broadband to a business line for work purposes and I didn't know if there is any gaming downfalls with that router or the business line?

[cje85]

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@Luke_113 wrote:

Can confirm on the new firmware on my business line with a Hitron CGNv4 (business hub) which I only ever run in modem mode, downloaded fine for me, infact it didn’t it failed or didn’t occur but I saw ‘sw init fail’ in the logs and did a manual reboot VIA THE GUI and not via pinhole and it updated fine, it seems that from 603 to 608 that they may have moved more processing across to the WiFi chip which is why WiFi is worse on 608 than 603 as I’m seeing a lot of threads talking about WiFi being worse now since going to 608 from 603

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I mentioned in another thread yesterday but the claim about them moving processing to the WiFI chip doesn't seem possible. The WiFi chip in the Hub 3 is apparently a Qualcomm QCA9880 which is quite old (introduced in 2012) and designed purely to send/receive WiFi data and pass it to/from the main Intel CPU. Also some of the Arris devices in the US affected by Puma 6 are purely modems with no WiFi capabilities, but have also been improved by recent firmware updates.

It seems to me that Intel have been able to significantly reduce the issues with the processor without offloading jobs to other chips, which don't seem to have the ability to do the required job anyway.

I'm not saying there isn't something in the firmware which may be causing WiFi issues but it won't be down to the WIFI chip doing work offloaded from the main CPU.

[nallar]

The puma 6 issue makes it impossible to run a nano (cryptocurrency) node on a VM connection, as it uses lots of separate connections.

Instant unintentional self puma 6 DoS.

[boltedenergy]

Important LPT:

if you were waiting desperately to receive the latest firmware update and want to keep it...

do not change your SH3's mode from router to modem or vice versa otherwise it will most likely revert to the original firmware when it fails.

[synner]

Hi,

I can confirm that I got the update in modem mode automatically, no reset.  I am on the 100Mb package and the Hub was still in modem mode after the update.

Hope that helps.

Bri

[Luke_113]

Hi connect123,

Nah the business service uses the same infrastructure but they use better external wiring, and also prioritise your traffic over the consumer offerings, gaming wise I expect it’s probably the same or more or less identical in terms of gaming.

Thanks for confirming not WiFi chip, wasn’t sure was just a theory based on having seen multiple threads about degraded WiFi performance and coincidentally all seem d to have 608 installed! Haha was just a coincidence 

[Connect123]

Ok cool that's good to know that the business line wouldn't make things worse 🙂

[Luke_113]

Just a heads up to all concerned, as I don't know whether consumers get notification of downtime?
Just has an email to state downtime on the 16th July @ 11pm - 17th July 7am with impact duration being 3 hours (usually this is no more than 15-20mins on these emails so this must be pretty significant if they're allowing 8 hours for the work and 3 of those hours with downtime!) and the work is required for 'Quite urgent diversionary works to protect one of our core 120 fibre cables.' by the sound of that and given its central london I'm going to assume this is a mass aggregation point for Virgin and likely a break out from their network?

Now call me out on this, but that to me sounds like a core bandwidth upgrade? I've been saying this has been an issue for months

[Luke_113]

Also, this being Virgin Media, what do you think the chances of them screwing it up is and taking everyone offline nationwide for the day?

[RedGooner]

Got the SH3 yesterday, been putting it off for ages. Now on the VM350 service.

Got a firmware update within 30 mins of setting up. Straight into Modem mode.

Now getting over 350Mbps, and no latency issues with online Gaming, on PC wired, and PS4 Pro Wireless.