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]

[ItsCraigo]

The Draytek does triple WAN. The online BT sales test says my guaranteed speed would be around 17mb. Not really sure what to do to be honest. The Draytek install is primarily to fix the **bleep** poor wifi signal out of the SH2ac /3 I have.

I'm a gamer but not avidly so. I play FPS type games so lag resilience is crucial. Sadly, I'm scuppered on all fronts it would seem.

I got Eurosport in SD though so every cloud.... 😉

[ItsCraigo]

Just plugged in the 2ac and let it boot. Rebooted it 10 mins later thinking it might latch on to VM network. No dice - I'm getting DNS errors when connected over wifi. Is this going to need a call to customer services to reactive like I did over the phone with my 3?

[MUD_Wizard]

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@ItsCraigo wrote:
Just plugged in the 2ac and let it boot. Rebooted it 10 mins later thinking it might latch on to VM network. No dice - I'm getting DNS errors when connected over wifi. Is this going to need a call to customer services to reactive like I did over the phone with my 3?

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Yes, you need to activate the SH2ac. If you plug the Hub 3 back in it will still work unless you've activated the 2ac.

[MUD_Wizard]

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@ItsCraigo wrote:
The Draytek does triple WAN. The online BT sales test says my guaranteed speed would be around 17mb. Not really sure what to do to be honest. The Draytek install is primarily to fix the **bleep** poor wifi signal out of the SH2ac /3 I have.

I'm a gamer but not avidly so. I play FPS type games so lag resilience is crucial. Sadly, I'm scuppered on all fronts it would seem.

Well games, excluding the downloads themselves, only require a few megabit to run. FPS games are particularly latency and jitter sensitive, so the BT connection with 17Mb should be far superior to what you have with VM for gaming. Streaming should also be more reliable, as anything less than 4K only requires up to 10-15Mb at most.

You could keep the VM connection for the speed, for downloads and other stuff, or save the money if you don't need the speed.

I got Eurosport in SD though so every cloud.... 😉

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Via TV or broadband? BT has Eurosport in HD too: https://community.bt.com/t5/Bills-Packages/Eurosport-1-amp-2-HD/td-p/1639713

Your peak time speed probably isn't fast enough for HD, unless it's a consistent 4Mb.

[SirThomas]

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@MUD_Wizard wrote:

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@SirThomas wrote:

Before: (and in modem mode!)     

Note: Before you go thinking that your Hub 3 was performing particularly bad that day..

On that day the packet loss and spikes in minimum latency were felt across the network regardless of the hub model being used.

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Oh absolutely, I've been keeping abreast of these things on various forums. Only intended for reference.
Excluding the spikes you mention, that's the norm for my Hub3, however.

The only strange thing I've now noticed is how different my DS power levels are since the changeover (+1.5dBmV).
I suppose that'll be due to having 8 rather than 16 channels in use, though?

Tom

[MUD_Wizard]

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@SirThomas wrote:

The only strange thing I've now noticed is how different my DS power levels are since the changeover (+1.5dBmV).
I suppose that'll be due to having 8 rather than 16 channels in use, though?

Tom

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No, the number of channels doesn't make any difference to the power level, as with a Hub 3, if someone goes from 8 to 12 to 16 channels, there's no change in power levels. It's all digitally sampled from the spectrum and then channels are selected via the CPU.

Whereas when you change from one hub to another, like Hub 3 to SH2ac, yes you will see a slight difference in power levels when going from model to model as the circuitry used to tune the signal is different, but still not affected by the number of channels in use.

[qpop]

Hello all.

I joined Virgin on 15th March on Vivid 200, put the Superhub 3 into modem mode, plugged it in, setup Thinkbroadband BQM and am getting the results below.

This is seriously disappointing. I contacted tech support immediately (Glasgow office maybe?) to be told they were unable to send out 2AC modems any more, and repeated a claim I had seen mentioned here that they are upgrading all customers to 3s, as the reason they cannot provide one.

Is this nonsense and do I need to call back and escalate? Who do I call and what do I tell them?

[ItsCraigo]

Perhaps buy a 2ac off eBay? They usually go for £10 and so long as VM can make it work, all should be well?

I'm not liking my SH3 either. Wifi is poorer than the 2ac and browsing seems laggy. I have no BQM of 2ac activity on my account though. Sadly, 5Mb up and down for me 95% of the time as I only use during peak hours when the poor network is saturated.

[BenMcr]

You will never get Virgin Media kit that will be activated from anywhere except directly from Virgin Media.

[eddiechatburn]

Certainly not had a firmware update, but it would appear something has happened this morning.

Hub 3 has lost connection - not even rebooted according to the uptime in the log, and the ping latency seems to have all but disappeared!!

Is anyone else seeing this?

I know we had an engineer from outside our area visit recently, and he advised our area had had considerable work don on the cabs, and it would take until the 20th for them to settle down, but I must admit I wasn't expecting this!

Could it be that the fault was never the Hub 3.0 but VM's own routing?