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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

itinfocus
On our wavelength

Totally agree that it's likely to be a very long time before any update is available to rectify this. Especially for Virgins customers.

The fact that Intel look to be playing hide and seek with the fix is also not encouraging.

If you look at the history of the issue the first reported problems were with ICMP ping which was patched to obfuscate the problem. Then reliable UPD DNS tests were developed. The latest beta firmware does admittedly do a good job of resolving that issue but when users do more digging the underling two second stutter is still present.

The Hub 3 (Puma 6) is quite honestly just not fit for purpose and I have an ever stronger suspicion that it wont be until a Hub 4, hopefully with a Broadcom SoC, that we finally get a reliable connection again.

It would be so much easier if customers could connect alternative modems as is common practice in the US. I'd love to put this behind me by just doping a few quid on a modem that actually works. 

itinfocus
On our wavelength

@qpop wrote:

So, how do we go about starting a class action in the UK for rolling out a known-to-be-buggy modem. Are we protected under the sale-of-goods act?

 

More to the point, why has Virgin decided to stop allowing users who are concerned to roll back to the 2ac? Very frustrating as a new customer!


Don't think the UK class action type suits are designed to address this type of issue. From what I can see looks to be more focused on consumer price protections.

Some more info Here if you want to read up and let us know.

Forget any communication or fix from Virgin Media it won't happen.  I must have posted a dozen times "The communications company that don't communicate"

This and other issues were noted during the beta test but the SH3 was rolled out full of known bugs.

The SH3 is not fit for purpose, the SH4 is the only hope.


@itinfocus wrote:

Not looking good based on the following:

https://www.theregister.co.uk/2017/04/11/intel_puma_6_arris/

https://www.dslreports.com/forum/r31353608-

I can understand that this is outside of virgins ability to fix directly but do have two areas of disbelief. Why do they refuse to admit that a problem exists when it's so widely documented and for gods sake why can't they issue a replacement hub 2ac until its resolved.

i work from home and use am dependent on both VPN and VOIP services that are seriously impacted by this bug.

Do virgin have any beta program available to test the partially resolved issues? If so how do I sign up?

 

 


They don't make hub 2's anymore and eventually stock of those will cease, at this point the hub3 is what we're likely to get as replacements, hopefully they have a decent hub4 in development that will solve these issues, or better yet, they ditch the whole hub idea and just make a rock solid standalone modem and just issue decent routers not coated in VM firmware, like they used to do with the old motorola modem and netgear WNR2000 routers

rio_w
Dialled in

Has anyone been successful in acquiring a Hub2ac? I really am at wits end with the Hub3.

wotusaw
Superfast

Thanks for the info. Makes very depressing reading. I only wish Virgin would communicate with the community about this issue.

I see no info posted here from Virgin at all. Am I wrong? Have I missed a post of theirs on this subject.

The very, very worst thing you can do is keep silent. Look at this post for example.....it's 52 pages long!

It's not going to go away.....ever.

Face the demon, Virgin. Let us know what's going on....please.


@wotusaw wrote:

Thanks for the info. Makes very depressing reading. I only wish Virgin would communicate with the community about this issue.

I see no info posted here from Virgin at all. Am I wrong? Have I missed a post of theirs on this subject.

The very, very worst thing you can do is keep silent. Look at this post for example.....it's 52 pages long!

It's not going to go away.....ever.

Face the demon, Virgin. Let us know what's going on....please.


What would you want them to say?

Even if they acknowledge the flaw in a piece of equipment they were provided there isn't a lot that can be done, they won't have stock of Hub2's and they won't order them in, they won't pay to swap out hub3's and there isn't a standalone modem option for them to try and offer either, i mean they know there is an issue and they will be doing all they can to fix it, the problem is there isn't much they can do, they can't make a fix arrive any sooner than it does, and any money spent on that will be a waste, its a better idea to start looking for a manufacturer for the hub4 and hope that it avoids the puma6 chipset, outside of that the owners of hub3's are pretty much boned, they won't allow 3rd party modems on the network so even if you were to buy a suitable device you couldn't use it

Hurry!

wotusaw
Superfast

shanematthews said:

"What would you want them to say?"

The smug answer to that would be............Anything at all.:)

However, I see your valid points and concur.