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]

[Guybrush85]

How many times do I have to tell Badvok that ping plotter allow tests of TCP and UDP and modem mode made no difference?

[Drewley]

@Guybrush85 Once more for the hard of hearing.

lol

[Anonymous]

So I switched back to the super hub 2.0 to see if it would make any difference and well it has made a significant difference. No doubt there is an issue with super hub 3.0

[RidingTheFlow]

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@YanYangC wrote:

This is my BQM and modem test.

The 100% packet loss on the BQM was swapping routers. Customer support said they'd send my a SH2AC, but they just sent me another SH3.0. Feelsgoodman.

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Your Puma test is using wrong server (non-UK) for some reason, that's what makes it results senseless - because ping will be too high even with perfect modem.

Try with server 46 (UK).

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

[shanematthews]

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@Anonymous wrote:

So I switched back to the super hub 2.0 to see if it would make any difference and well it has made a significant difference. No doubt there is an issue with super hub 3.0

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Nobody said there wasn't an issue, its a known fault with no known fix date, just got to wait for the hub4 to be released eventually 😛

[GMAN73]

Saw this on VMs twitter page LOL

https://twitter.com/virginmedia/status/912998779053363201

[wotusaw]

Are you the **** kidding me!!!!!!!!!!!!

I suggest we all ring them and complain or at least inform them of our problem with the HUB 3.

I changed upto 300mb Vivid Gamer and there was an improvement from 200mb. However the HUB 3 is deeply flawed nonetheless with huge yellow showing on the widget tests.

Anyway, I shall ring them and report back. I will be polite...honest.

My main complaint is the lack of information about this. When's the update coming or has it been cancelled. Just let me know stuff for the love of all that's holy.

Are you listening to your customers at all VIRGIN????????

Is there a moderator in the house?

Talk to us!!!!!!!!!!!!!!!!!! 

[RidingTheFlow]

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@GMAN73 wrote:

Saw this on VMs twitter page LOL

https://twitter.com/virginmedia/status/912998779053363201

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Well, did you really expect whoever staffs this PR twitter account to publicly admit there is an issue? Obviously they will say that everything is fine and most people are happy (that's what they were saying before they've appeared on watchdog too).

Same applies to sales staff (who are "not aware of any issues with SH3"). They are not being paid to discourage customers, so will say anything to make them at ease.

[Badvok]

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@Guybrush85 wrote:
How many times do I have to tell Badvok that ping plotter allow tests of TCP and UDP and modem mode made no difference?

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Well you obviously have your own agenda and I guess denial of any mitigation helps you with that.

Here is my current dsl reports puma 6 test result using modem mode:

I don't have the time to switch it back to router mode to show how bad it was before but there was a lot more red as you'd expect with 20 downstream channels locked. As I said, modem mode doesn't fix it, but it does help a bit.

[Guybrush85]

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@Badvok wrote:

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@Guybrush85 wrote:
How many times do I have to tell Badvok that ping plotter allow tests of TCP and UDP and modem mode made no difference?

---

Well you obviously have your own agenda and I guess denial of any mitigation helps you with that.

Here is my current dsl reports puma 6 test result using modem mode:

I don't have the time to switch it back to router mode to show how bad it was before but there was a lot more red as you'd expect with 20 downstream channels locked. As I said, modem mode doesn't fix it, but it does help a bit.

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I did a puma test before and after and the results (which differ from test to test) and made no noticeable difference and so did a lot of other people on this thread. I ran ping plotter in both scenarios, which isn't just a basic TCP test with a preset data rate and it made no difference. We don't even know the environment of both tests and if you set the same server for each.

Here's a nice ping plotter graph, in modem mode using TCP to google on an R7800, cBR-8 with 24 channels and all levels in spec. Doesn't seem fixed to me.

 

As side from that, you say a BQM might not look pretty and that's it, but in it's current state ICMP is being dealt with in the same way that TCP and UDP is. It's only in newer firmwares when the moved ICMP traffic to the PP that it changed, so for us, it's still a representation of latency of the hub 3. Again, you've not bothered to prove that one way or the other, so here's an ICMP plot for you.

Seems familiar...