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Hub 3 / Compal CH7465-LG (TG2492LG) and CGNV4 Latency Cause

Datalink
Up to speed

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]

4,478 REPLIES 4,478

Sky_Lord
Up to speed
I bet tech support have the very basic of training. I bet Virgin themselves with have very limited input into the firmware.

Hopefully it will just be a case of the firmware being prepared and sent to Virgin to send out to everyone.

Personally I haven't noticed any problems with gaming, but also my latency spikes are nowhere near as frequent or as high as others on here.

Tempted just to plug in the SH2 and see what happens as my speed hasn't changed to a higher tier.

To be honest I didn't have much issue with it until last week when the hub got stuck 'updating' after a reboot and now it's terrible - it's absolutely useless for online gaming, even slow paced games, I bet you'd get **bleep** off on Candy Crush atm with my connection.

Wonder if there was a beta fix that's made the issue worse?

what I can say is this seems to be worse the more channels you have. When I was on a hub 3 with 8 channels, my graph looked about the same as it did on the 2ac, but the second I moved up to 16 then things looked a lot worse.

--------------------------------------------------------
Look behind you, a three-headed monkey

Hi Butler,

I don't have my hub yet but are you able to configure the number of channels the Hub broadcasts on in the setup?

Thanks,

benjumi -  "Sometimes it is better to be silent and be thought the fool, than it is to speak and be confirmed as one".

benjumi
On our wavelength
Hi Sky_Lord,

Are you running the SH3.0 with the Vivid Gamer 200 package? What games do you play and what sort of average connection stability do you see?

Thanks,

benjumi - "Pop de ping - Microwave (Welsh)"

I do have the Hub 3.0 but I refuse to pay extra for the 'gamer' package as it's completely unnecessary, ping and latency is king.  You don't need anywhere near 200mb for gaming and the virgin gamer package will not give you any advantage over someone on the lowest speeds.   They should name it the torrent package as that is what it helps with as you don't get throttled. 

I play both PS4 and Xbox one. Current fave is Battlefield 1 and Forza Horizon 3, I've not had any issues, or witness myself lag or had any friends comment that I'm lagging  There is packet loss on Battlefield 1 but this isn't the hub or Virgin and to do with EA. I check my graph and there is no sign of packet loss. 

Everything on the consoles is wired and wifi speeds are good, they did seem flakey the first day but it seems to have bedded in well. 

I did put my hub 3 into modem mode to get rid of those spikes of latency and use my Asus RT-AC68U like I did with the SH2, however the latency on the graph was worse than the Hub 3 in router mode, so I took the Hub 3 back out of modem mode as it was better which was odd. 

MUD_Wizard
Superuser Emeritus
Superuser Emeritus

@PhillipM wrote:
To be honest I didn't have much issue with it until last week when the hub got stuck 'updating' after a reboot
It shows that 'updating' message when the hub goes offline for any reason. The message doesn't actually mean it has updated the firmware; you need to check if the firmware version actually changed or not to be sure.
and now it's terrible - it's absolutely useless for online gaming, even slow paced games, I bet you'd get **bleep** off on Candy Crush atm with my connection.

Wonder if there was a beta fix that's made the issue worse?

No, so look for a more regular cause like an SNR fault. Suggest you setup a BQM graph: http://www.thinkbroadband.com/ping


@Butler85 wrote:

what I can say is this seems to be worse the more channels you have. When I was on a hub 3 with 8 channels, my graph looked about the same as it did on the 2ac, but the second I moved up to 16 then things looked a lot worse.


Yes, I noticed the same trend from viewing peoples BQM graphs and channel stats in the forum. I've mentioned it before long ago. Though some people's hubs may buck the trend, for various reasons.

MUD_Wizard
Superuser Emeritus
Superuser Emeritus

@benjumi wrote:

Hi Butler,

I don't have my hub yet but are you able to configure the number of channels the Hub broadcasts on in the setup?

No, you cannot configure the number of channels you get on the Hub. That's determined by the type of CMTS you have in your area and how it's configured.

The CMTS is what broadcasts the downstream channels and receives the upstream channels at Virgin's end. Since it's broadcasting the same downstream channels (and TV channels) to everybody in an area (on the same node), then everybody gets the same number of channels.

8, 9, 10, 12, 16 and 20 are all possible downstream channel configurations, though the bold ones are more likely, as upgrades continue.

2 upstream channels are the default for most areas, with some areas having 3 or 4 channels.

The only situation where you have a subset of the downstream channels (Receive Channel Set) or upstream (Transmit Channel Set) is when one or more of the channels becomes unusable due to noise or other issues. This is called Partial Service mode, where the hub tries to stay online with less channels: https://volpefirm.com/docsis-3-0-partial-service/

Thanks,

benjumi -  "Sometimes it is better to be silent and be thought the fool, than it is to speak and be confirmed as one".


🙂 http://electronicdesign.com/communications/what-s-difference-between-cable-and-dsl-broadband-access