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]

[tonycv51]

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@fat4l wrote:

So I tried this router ASUS RT-AC86U Wi-Fi AC2900 USB 3.0 Router and SH3 in modem mode, with new firmware, 350Mbit, and the wifi speed was crap.

With my devices close to the router(50cm, same room) I wasnt even getting full wifi speed which for me is about 388Mbit. I'm returning this router and need to try another one which can actually do full wifi speed in the same room, but I heard the "modem" mode may be causing it ?

Any suggestions ?

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I have the previous gen Asus AC 68U. On a 200 connection getting 205 on Speedtest with iPhone 6 in next room.  

Its possible you’ve got a faulty one but if you haven’t already do a WiFi survey on both 2.4 and 5 ghz to check for interference. Also check owners thread for your router on smallnetbuilder for best settings. Do you know for sure that you were connected to 5ghz WiFi ?

[fat4l]

Yeha I checked all, several times. Tried to change some settings, channels etc. Nothing helped.

Wired I can get 388Mbit but when on Wifi then max is about 320Mbit or so..... Tried my laptop and my phone which are both doing full wifi speed of 388Mbit when connected to SH3 in router mode but they cant do full wifi with asus. I guess its asus routers fault as wired all is ok, and my wan connection between asus and SH3 is 1000Mbit/s.
This means that SH3 is sending full speed to asus router, which is then not passing it onto wifi for whatever reason.

Now im back with SH3 and full speed on wifi ez.

Im thinking of trying ASUS RT-AC88U AC3100. But this router is older than ASUS RT-AC86U Wi-Fi AC2900 and thats by about 2-3 years. Not sure if I want to invest 240£ in this old router.

If I wont go Asus, not sure what else to go. Maybe NETGEAR R8000P Nighthawk X6S Tri-Band AC4000 but not sure if I like it software wise. Hmmmm

[Connect123]

Only guessing here but it seems that the router isn't allocating 100% of the wireless speed to the receiving device, like it's keeping a bit in reserve for whatever reason 

[philjohn]

Check the 5hz channel and channel width - you'll want a full 80Mhz channel to get max 802.11AC speeds and even then it can be variable.

[lynxblaine]

It's almost certainly the Wireless channel width as mentioned above. You need the 80MHz width for enough bandwidth to be delivered over wireless. 

[Luke_113]

I must be of a small minority who doesn't understand why people need such high wifi speed? For me basically anything about the 40mb speed range is absolutely fine for me on phone/tablet anything more than that and I don't feel theres any benefit, its not like your webpage loads faster or netflix streaming suddenly gets better lol. Personally if I were doing a large transfer of data I wouldn't be doing it via wifi, the sustained speed throughput of wifi is nothing compared to wired.

Maybe its just me haha

[philjohn]

In a lot of houses it's impractical to use wired internet everywhere.

I've got a large house and running ethernet between the office and the router would either result in a cable being a trip hazard or a long spell digging out traces in the walls, neither of which are an option.

So if I have a large download (e.g. Steam game) having fast wireless is a boon - and it's possible to have. I get around 320Mbps upstairs.

[tonycv51]

I don’t know why you’re not getting max speed in your test vs the SH3 but if you look at this test you’ll see that another router may give you a slightly better single wi-fi test with the right device but they won’t come close the 86U for overall throughput due to much slower CPU i.e in real world conditions, multiple devices attached, QoS enabled etc. 

[fat4l]

well it was set to 20/40/80MHz, but not directly 80MHz only.
With SH3, I use the same setting of 20/40/80MHz. So? I dont get it.
It should really get up to 1734 Mbps with 802.11ac or even up to 2167 Mbps with 1024QAM, so maxing out on 320Mbit or so is ....weird.

I ordered ASUS RT-AC88U AC3100 which is the older model but still should be very good if not better yeah ?

[mbulliva]

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@fat4l wrote:

Yeha I checked all, several times. Tried to change some settings, channels etc. Nothing helped.

Wired I can get 388Mbit but when on Wifi then max is about 320Mbit or so..... Tried my laptop and my phone which are both doing full wifi speed of 388Mbit when connected to SH3 in router mode but they cant do full wifi with asus. I guess its asus routers fault as wired all is ok, and my wan connection between asus and SH3 is 1000Mbit/s.
This means that SH3 is sending full speed to asus router, which is then not passing it onto wifi for whatever reason.

Now im back with SH3 and full speed on wifi ez.

Im thinking of trying ASUS RT-AC88U AC3100. But this router is older than ASUS RT-AC86U Wi-Fi AC2900 and thats by about 2-3 years. Not sure if I want to invest 240£ in this old router.

If I wont go Asus, not sure what else to go. Maybe NETGEAR R8000P Nighthawk X6S Tri-Band AC4000 but not sure if I like it software wise. Hmmmm

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Are you using the stock Asus firmware, or the Merlin one?