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]

[コナー]

I've done a lot of complaining and as of yet I've been promised a 2AC but was given 2 Hub 3s instead.

[wotusaw]

Datalink@

"If you want to see the graphical image of the problem, download pingplotter and ping the CMTS, which is the first address beyond the modem or router (modem in Modem Mode) enroute to anywhere.  Pingplotter will run...................................."

Thanks. When I have time will have a go at that. Your name is very descriptive.

[Datalink]

🙂  Just keep in mind that the Pingplotter default interval is 2.5 seconds, so, you have to override that and use times well below 1 second to see the spikes.  10 ms times are useful for Pingplotter results.  

As well, when you have pingplotter up and running, right click on the column title bar to bring up the column menu and select MAX and ERR.  Those columns are not shown unless you select them.  Drag those columns to the right to sit somewhere near the Min and Avg times. 

And finally a warning.  Pingplotter averages the data that is displayed when you attempt to show longer timeframes.  So, with a low ping interval, as you step up from a 1 min plot, to 5 min, 10 min, 30 min....24 hours, Pingplotter looks at the number of horizontal data points and instead of showing the MAX and MIN times on the plot, it averages the data.  The end result is that as you increase the time span of the plot, the plot itself looks better and better as the high ping times are all averaged out.  Step back down to 1 min and you will see the higher ping spikes.  On a 1 min plot, which is the lowest that you can display, the same problem applies as you decrease the ping interval.  You end up attempting to display more data in the same time frame, with the same averaged results.  This is where the MAX time in the text data comes into play.  With the upper text data time set to Auto, it will display the results for the same timeframe as the selected plot timeframe below, but, the text data will show the real MAX time, whereas the plot MAX time will be averaged down.  When you see that the text and plot MAX times match, then Pingplotter isn't averaging the data.  When the text MAX time is larger that the plot MAX time, then you know that for the combination of the selected plot time and number of data points you are attempting to look at, Pingplotter is averaging the plot results.  Unfortunately Pingplotter doesn't advise the user of its choice to average the results instead of including a selection to show the MAX and MIN times in a given horizontal pixel range. Multi-ping, also sold by Pingplotter has that selection although the colours are less than stellar.  From what I remember, it uses fluorescent colours to show the MAX times, ugh....

[purplemonkeyspa]

Stoddy27

I just bought a new router from the Archer range (C2) and can't seem to get it connected to the internet. I've set it up as per tp-link's own instructions but getting it online is proving to be pretty annoying. Any chance you could help us out?

[PhilHornby]

My  measurements regarding Trial Firmware (using Draytek Vigor 2860 -> HUB 3 (modem mode). :-

Package 200/12

I thought the spikes were the Samknows tests - but they're not (having turned it off for a few hours); so something on my network warrants investigation...

The Samknows tests note the improved ICMP latency and also an improvement in DNS lookups of circa 2mS.

I forgotten all about it, but during the SH2 Trials, I set up a UDP monitor - and is been running all this time in the background.

It uses the NTP protocol to measure 'roundtrip' times to Virgin Media's NTP server - so it's entirely within the VM network.

It parses the output of this command: 

w32tm /stripchart /computer:ntp.virginmedia.com /dataonly /packetinfo /period:1 /samples:19

The purple trend line computed by Excel implies a significant improvement in UDP performance. I think there's a possibility that my red line denoting when the firmware went live is slightly inaccurate.

[Datalink]

Out of curiosity how are you collecting the return times so that you can plot them?  Using Wireshark?  I'm not familiar with w32tm, but, it looks rather interesting for data gathering purposes. 

[bbyrne]

Phoned up and complained, and they're sending me out a SH 2.0ac, said they're getting a lot requests regarding this issue.

Asked for an ETA on fix and they don't have one, it's safe to assume it's going to take a while.

Ping to router through ethernet 1-10ms and up to 100ms every now and again, not acceptable.

[Stoddy27]

@purplemonkeyspa have you changed your VM router into Modem mode and connected your TP-link to the modem mode port on the back of the VM unit ? should be the last port on the VM router

[purplemonkeyspa]

Stoddy27

Thanks for getting back to me.

Yes and yes. After many false starts I was finally able to actually get in to the router's settings and setup options and looks ok but it's just not connecting to the net. Get an "unknown error. No internet" message.

Here's what I have.

Blurred the MAC address for which I used my SH3's and blurred an IP that was assigned automatically by the router.

https://imgur.com/e1yzbUH

Does that look ok?

[shanematthews]

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@Stoddy27 wrote:

I am sorry but to say pinging the gateway is not a good test is incorrect - If you are seeing latency in your internal network to internal devices consistently this highlights the problem and you will have the same latency outside of the network - I have never seen a network device which has anything but 1/2ms latency internally. 

My network uses high amounts of traffic hence why we are on the highest tier package to avoid slowdowns this problem really affects my network sometimes I see 15-16ms ping (any time of the day or night) sometimes I see 600ms ping. I can't use BQM as my router does not allow for external ping for security reasons so I can't provide that data but what I can say is since the SH3 went in my locally hosted websites suffer massively. 

Our network monitoring shows constant spikes at random times where there is little to no traffic hitting our network.Can anyone let me know the Beta test firmware version number I want to see if I can speak to someone at Virgin to request this my contract ends in 3 days.

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Not always, a good router will put internal ping traffic at a much lower priority than actual outbound traffic, some routers on the internet actually completely disregard ping traffic altogether as its not seen as important, pinging the LAN side doesn't immediately indicate an issue unless its massively high, and when i say massive i mean in the 2000ms sort of range, if the router is busy it is designed to prioritise certain traffic over others