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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 have the black Arris and same model number. However I only have 12 channels on the downstream. I'm on the vivid 200.

Adduxi
Very Insightful Person
Very Insightful Person

@boltedenergy wrote:

@BlackDwarf wrote:

@boltedenergy wrote:

That's Terrifically bad! 
Can you post your channel stats and hardware setup similar to my post?

Sure. SH3, Homeworks 300/20, White Arris TG2492LG-VM in Modem Mode on  9.1.116V FW

GY6stfy


Perhaps a more dBmV/SNR loving geek can comment further but to me your downstream power levels look ridiculously low? 

Have you checked it with support?


Those power levels are fine, anything between -6 and +10 are okay. My Hub 3 would hover around those levels for DS

I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more

Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks

Looking at the Channel stats and BQMs make sense.  SkyLord you're only running 12 channels down so your latency effects aren't as bad as those seen with boltedenergy and BlackDwarf.  They're running 20 channels on the downstream so the amount of processing increases as does the latency effects that are seen.  This problem becomes worse as the channel count goes up, but, its a pretty big difference going from 12 to 20 channels down.  I suspect that there are additional differences due to the type of modem that is used as well.  There are variations of this chipset, ranging from a straight modem to a telephony modem to a media gateway modem.  Fwiw, although the problem exists for 20 channel Hitron modems, this really didn't become an issue until the arrival of the 32 channel gigabit modem this summer.  

Looking at the BQMs for Skylord and boltedenergy, the background latency isn't bad.  That all depends of course on how those numbers are arrived at, but, if they really represent the average numbers from the server to the pc, they're not bad.  Blackdwarf's BQM shows a higher background latency, which is most likely due to higher usage rates for his CMTS.  

Add on top of my BQM pretty constant heavy usage my end, which could add extra ms on to the ICMP reply.

benjumi
On our wavelength

All these threads have taken the wind out of my sails about my impending switch to Virgin Gamer 200 this Saturday. Fully expecting ping spikes, latency and no end of issues, so will likely be cancelling within the 14 day money back guarantee period; i.e. the Sunday. 

I had such high hopes that Virgin might be just a little less disappointing when compared to Sky. Will have to start looking at alternative providers on Monday I think!

I was so looking forward to the 10x increase in download speed. Smiley Mad

Sigh.

Thanks for your brief yet intriguing interractions, Virgin Media forums! 

benjumi: "They're dead Dave. They're dead, they are all dead Dave, Dave they are all dead."

benjumi
On our wavelength

Just in case it brings any form of levity to the situation, I had the following exchange with the Community Welcome team, short lived as it was.

Hey there,

I noticed you have recently joined us so I thought I'd send you a quick message to welcome you to the Virgin Media community and to introduce myself.

My name’s Kev and I'm one of the Moderators who looks after the Community. One of the key principles of our Community is that support is provided by our members for our members. If at any time you have any questions with regards to the Community please feel free to message me and I will get back to you as quickly as possible.

To help you get settled in our getting started section is full of really useful tips.
http://community.virginmedia.com/t5/custom/page/page-id/WelcomeGettingStarted

I look forward to reading your posts and contributions soon.

Kev
Community Moderator

I replied with the following.

Hi Kev. Thanks for getting in touch. Are you a community mod that is employed by Virgin or are you just a plucky customer who likes to help people? (Not meant as a slight, just need to know so I can pitch my questions at the right level).

You may notice that I have already made some posts on the gaming forum (even got some medals for my troubles!). I am having my Virgin Media package installed on the 17th of December, however as my posts may have suggested, I have read some very disturbing posts about issues with the Hub3.0 hardware and packet management, causing users to suffer horrendous packet loss, jittery connections and all in all made their online gaming experience miserable - something that if I experience will lead me to cancel the service within the 14 day money back guarantee period.

I am reasonable enough to not have berated Virgin's lack of acknowledgment or community engagement on the issue (the threads are increasing in number and views on the issue) however reading through the engagement your support teams go through both on the forums and your Twitter page, I am left even more disconcerted about how Virgin are handling the issue. My overall positive experience with your company is fast depreciating even though I've technically not started with your service yet! 

Whilst the information readily available online is tantamount to certainty as being the problem (Puma 6 chip set needs a firmware patch), I understand why Virgin is taking the plausible deniability route at this time - the company I work for would do the same if a significant firmware issue had been found in a flagship product. 

All of my ramblings aside, there appears to be some hope that not all Vivid Gamer 200 customers are suffering so the proof will be in be pudding on Saturday, however I really hope Virgin are working as proactive with their Arris and Intel partners to get the issue resolved quickly and to everyone's satisfaction; perhaps with some humility and customer engagement thrown in for good measure! 

I look forward to more than just a generic response but I understand if the powers that be may not allow too much honesty at this time (if you're being held hostage, reply with ... At the end of your message and I will alert the authorities!)

I eagerly await your response.

Just in case it warrants a wry smile from anyone who has been suffering a while. Smiley Very Happy

benjumi: "Fork Handles."

Benjumi don't bother with the gamer unless you stream. Vivid 200 will be fine. I have the Hub 3 and I have no problems with lag. There is a problem with the Hub 3 that will be fixed, but y the looks of it the Hub 3 and homeworks 300 sound like the one to avoid with the Hub. My latency spikes which are infrequent and not great, maybe just caused by the hub prioritising different traffic rather than responding to the ICMP ping.
I get the speeds as advertised and the wifi for me is decent too.

benjumi
On our wavelength
I do occaisonally stream, Sky Lord, but not regularly. I got the impression that the issue was related to the Hub in general rather than the line to which it is connected - I haven't seen any evidence to suggest otherwise at the moment.

I am conscious of the throttling too, but I may be willing to sacrifice that if I can still achieve a solid gaming experience with no packet loss.

Thoughts appreciated.

If you stream then yes go for the gamer package. Honestly I'm sure like me you will find it fine. It appears to be the 300 package where the major trouble happens. My mates say I don't lag online.

I wish that were true. I've the SH3 and VIVID 100 and there's plenty of lag - http://www.thinkbroadband.com/ping/monitors/share/0ae0fad6d48a92ac0a692439c214ce67-15-12-2016.html