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]

[BrokenFibre]

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wrote:

Has anyone here had SKY fibre unlimited 62mb-76mb and Virgins 350mg.

How do they compared in actual gaming?

Virgin is hugely faster but does that show up in gaming especially with the HUB3 latency/maintenance mode/whatever problems against SKY fibre 62mb-76mb?

Sky comes in at £50 and Virgin at £90 a month. As said Virgin is much faster. Need someone whose actually tried BOTH.

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here you go on the 26th December 2017 when I had both VM 200/20 on a SH3 in router mode and my current NOWTV connection 38/10 using a separate modem and my own router (uses the same network as Sky).  When I just had VM I used the SH3 in modem mode with my own router.  Made no difference.

[Badvok]

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wrote:

If you're really observant you can see this in texture tearing,

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I think I've heard everything now, the SH3 actually being blamed for screen tear!

[Andrew-G]

"I think I've heard everything now, the SH3 actually being blamed for screen tear!"

Give it some thought, then:

• When latency spikes, the client computer experiences a hiatus in its communication with the server.  That is a simple matter of fact when you get a rise in latency whilst on-line gaming, regardless of cause. 
• If the interrupt is for example 140 ms, then a monitor running at a 60 Hz refresh rate will lose those eight or nine frames of data from the server, and be out of synch with the server (more so for larger latency spikes). 
• All of that time the client has no input/output, but the game continues on the server.
• When the client re-establishes a low latency connection, the monitor will repaint the scene as per the current version of events on the server, and that will be out by those eight or nine frames. 

Now, you tell me how a client computer will handle that discontinuity?  Some things (like other player positions and movements) will appear to jerk into their new position, but textures will sometimes appear to tear, because the geometry of a mapped texture can't be smoothed when you have that sort of break.  On a textured (as opposed to graduated or plain) colour surface this tearing will be more apparent because the texture gives it away even if the tear is a "positive overlap".  It isn't there all the time, but I can see this regularly on a fairly high spec gaming machine, and when visible it will usually repeat every couple of seconds (as I'd expect given the Puma 6 CPU interrupts).  And the other thought is that this didn't happen with my SH2.

It isn't huge, but I can see it.  If you think that the Hub 3 doesn't cause this, then the only alternative is that despite a fixed refresh rate, the client computer is somehow able to smoothly catchup with the server after each latency spike, and to morph texture maps to ensure that any missing data for the image is essentially made up on the fly.  Would you really want to associate even your pseudonym with that claim?

[WildWayz]

Screen tear is purely down to the monitor refresh rate being out of sync with the game - hence why Gsync / Freesync was created to remove that. Or the old method of enabling Vsync - but that also brings in an element of input lag...

Latency will not cause screen tearing.

[Andrew-G]

I'm not talking about whole screen tearing.  This effect is within polygons that have a texture being displayed.  No amount of hardware synch fixes can alter the fact that the client has to catch up by the example of 8-9 frames, and that the client will be mapping a different image to that displayed before. The jerky movement of some other players is an obvious effect, if you consider what has to happen when a texture across an area of screen has the same jump, what you'll have is a momentary thin wedge of missing or overlapping image.  It's like cutting a sheet of graph paper and putting it back at a very slight angle - either side the pattern is the same, but it won't join correctly, creating that obvious discontinuity, that in a game appears as a tear.

As I said, the only way that you won't have such visual discrepancies is if the client can make up the lost data (which I assert it cannot), or if the client could buffer the missing data and then inject them back in some accelerated mode (which is nonsense on a monitor with a fixed refresh rate).  I'd accept most people don't notice or don;t care, and that there's other reasons for graphical distortions, but what I'm describing is down to the mathematics of displaying a moving image when you have a break in I/O significantly longer than the refresh rate of the screen.

If you want to say "oh no it isn't", then feel free, but let's then leave my assertion as an area where we agree to disagree, and you can explain what you think happens to an image when your PC has continued local movement of your avatar, but then gets a new set of data from the server that is out by around ten frames?  Think about the graph paper.

[WildWayz]

The point is, is that screen tearing is completely different.

What you are describing is simply the client/server catching up. The definition of screen tearing is solely used with monitor refresh rates - period. 

What you mention is kinda like hitting fast forward to catch up a paused live tv stream, so to speak. Same with seeing enemies jump across the screen suddenly... or when there is a desync, you'll see them run across the screen and into a wall as that was the predicted path - hence why years ago people would shout "OMG the netcode is rubbish!" as it wouldn't take into account ping differences, lag etc

Either way, the only time i've ever experienced things you have described is if i am playing with my Aussie pals on an American server... which has so many different ping responses (higher to Australia than America, then me in UK). Destiny is particularly bad with this respect with Thralls teleporting about etc

But it isn't screen tear. You can say "it is a screen tear-like feel" - but it isn't screen tear in the sense of the phrase... which has been a defecto description associated with monitor/gfx card refresh rate issues.

[PacketNerd]

Hi All

I'm suffering from this fault. Spikes in latency occurring regularly, spaced 2 seconds apart.

I've called the support team in hopes of getting a SH2ac and had no joy, tried going through cancellations as someone suggested and had no joy there either.

People that have suggested speaking with a "broadband specialist", how did you get through to one? I've asked on every call I've been on and no one seems to know what I'm talking about. Do I just keep calling the regular support number with the hope of getting someone that knows what a broadband specialist is?

[コナー]

Try asking to be transferred to customer relations, they seem to know a bit more about that sort of stuff.

[tommey]

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wrote:

Do I just keep calling the regular support number with the hope of getting someone that knows what a broadband specialist is?

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Like I have said before earlier in this thread you need to speak to the retentions department they will then be able to get a so called broadband specialist to call you back eventually.

[rs888]

Can't see anything anything about SH3 firmware 9.1.116.603 on the forum so I shall post here about it. I am not part of any current trial so I assume it is being rolled out for general release?

Before and after firmware upgrade.

Better than before at least.