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]

[Andrew-G]

@flyg

<i>Should i keep trying to get them to activate?</i>

If the call centre staff are following a script (which they undoubtedly are), then phoning again will probably have the same outcome.  You could try calling the UK based retentions team and asking to cancel your contract as unfit for purpose.  They tend to be quite keen to keep people on contract and so may be able to route the request to somebody able to think, instead of the off-shore script jockeys.

Of course, if Retentions can't or won't help, would you actually cancel?

[jonathanm]

I've read through the opening posts and for some time been following the latter pages, after getting the Hub 3.0 and doing reading around some other issues.

Firstly, before anyone says, it has been proven unequivocally that there are issues with the Puma 6 chip in the Hub. However, I was pondering the other day regarding the numerous BQM's that people have running against their routers as to whether it could actually be compounding the complaints that people are having whilst gaming. Now not everyone is running a BQM and it was merely a thought.

Let me explain my train of thought, a ping every second under no load or normal circumstances would highlight the latency issue. However if you are trying to use the connection for a low latency application (e.g. online gaming) albeit only a ping once a second, this is another load on the Hub that could be making the experience every so slightly worse (from an ICMP ping perspective). 

In a closing statement, I'll caveat this post that I'm just contributing a thought to the discussion and have done nothing other than think on that thought and read through the info about the BQM on the Think Broadband page.

[appleaday]

I'm now considering BT's infinity 2 because of this issue, the Black Friday offers are brilliant especially as I have sky and pay for BT sport separate, just worried about the much lower download speed, will I really notice in the real world, any one have any experience with BT?

thanks

[tommey]

---

@appleaday wrote:

I'm now considering BT's infinity 2 because of this issue, the Black Friday offers are brilliant especially as I have sky and pay for BT sport separate, just worried about the much lower download speed, will I really notice in the real world, any one have any experience with BT?

thanks

---

I use BT Infinity 2 just for gaming and the difference is black and white.

You will only notice the difference if you do lots of downloading of LARGE files as everything else like streaming Netflix or amazon etc does not require huge speeds in order to watch without buffering, even a 8 meg ADSL connection from 2005 would be fine for such usage.

I have BT Infinity 2 and Virgin, the family use Virgin for everything but gaming I use the BT connection for gaming and it's superb.

Just look at my BQM's below for a comparison

[theoven]

I get more speed but still have the old version firmware and spikes

[fat4l]

Well all I can say is I managed to get SH2 AC activated(well it wasnt even mine but my friends).
I had to call them several times.
I spent hours on the line.
In order to get SH2 AC, you HAVE TO talk to broadband specialist.
The Broadband Specialist is ONE, yes, ONE person so it takes up to 1 week for him to call you back. They give you time and date for the call.
Only he can send you SH2AC.
He knows about the issue with latency(the rest of ppl there prolly dont know what you are talking about).
Max speed supported is 200/20Mbit.
If you however have SH2AC at home, and it is registered with some other account(even yours old account or whatever), it will not activate- thats their policy.
In order to unregister the mac address from other account, they need to talk to the owner of the account and he has to confirm that they can unregister the mac address from his account, even if the account is already deactivated.
So ? What you are waiting for ? 🙂

[appleaday]

I don’t really download that much to be honest, the estimate is between 64 and 80mb but the upload is showing as 19mb, think I’m going to give it a whirl

[Andrew-G]

"just worried about the much lower download speed, will I really notice in the real world, "

Depends what you're doing.  In my experience I've not really noticed the increase in speeds in day to day use since my VM connection was at 50 Mbps, and now its 200, having hopped 50>100>150>200.  Personally, I'd think if you can get a 78 Mbps Openreach connection, you'd have no complaints.  Ask neighbours who they use, and what their experience is, and if you're on good enough terms ask them to do a BQM test and an Ookla test run, then you'll have have some comparable data.

In measurable terms Openreach will at best always be slower than a 100 Mbps+ cable connection.  But how often does that matter?  Most huge downloads (say a W10 or Steam update) happen in the background, they're infrequent.  Even if you had to sit and wait, the convenience difference between a ten minute or a twenty minute download is not material - it still clags your connection up for a duration that approximates to a coffee break.

[ShadowOfDeth69]

@theoven

I'm on the same package yet I see nowhere near those speeds. Granted I'm using wifi but still. I'm testing stood right next to the Hub, nothing blocking it, no other devices connected and my phone is more than capable.

The best top speed I've seen in real world use was downloading an app from Google Play at 29MB/s (230ish Mb/s) but according to speedtest.net using different far/near servers I'll get on average of 260-280 while TBB rates my speeds at 130.

[ShadowOfDeth69]

https://imgur.com/buhX7u6
Speed test results over the last week for Vivid 350