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]

[Peter_JS]

Morning all.

Received my Virgin media superhub 3 yesterday.

Bandwidth performance is fine, reaches rates as advertised/marketed (200Mbps DL, 20Mbps UL).

However, this device is *not fit for purpose* in terms of its latency performance.

Its a major step backwards in terms of latency as others have reported widely across America, Canada and UK.

I've attached 4 ICMP plots.

All performed from a high performance Linux X86 machine over wired 1GbE network.

SH3 configured into modem mode.

SH3 information:

Hardware version	: 10
Software version	: 9.1.116V

Ping plots:

Internet plots:

1) The traditional Thinkbroadband plot, showing switchover from SH2 to SH3.

2) 400 pings to the bbc, approx 7am 22 April 2017, illustrating the period latency problem.

Local network plots:

3) 300 pings directly to the Virgin Media SH3

4) 300 pings directly to my Asus router, to illustrate the type of performance one should expect.

Observations

A) My measurements concur with everyone else's: this device introduces serious packet latency problems.

B) There is a periodic nature to the worst of the latency issues.

C) At these worst case points, several ping packets (which are circa 1 second apart) are affected. Hence this problem occurs over a long period of time.

D) The minimum and average latency performance of the device is really bad [3]. Compare to my Asus box [4], which worst case was 0.6ms, this device's best base performance is 1.6ms, with an average of 5.6ms.

Comments and conclusions

Clearly VirginMedia are aware of this issue and the issue lies with Arris and Intel with the Puma chipset.

I am otherwise happy with VirginMedia, their internet performance has been generally good to v.good for some years now.

The performance of my SH3 device appears consistent with other's measurements.

Even if there is a good firmware fix for the worst of the spikes for ICMP, IPV4 and IPV6, I have doubts whether they (Intel & Arris) will address the minimum and average latency issues. (This is visible in plots [1] and [3].) Throwing away nearly 6ms of latency locally, when a round trip to the beeb used to be around 14ms is not acceptable in my opinion. I speculate that users (particularly gamers) will struggle to argue this point with VM staff though.

Thus its not fit for purpose; so I will be calling Virgin Media this morning to discuss returning it and returning to my SH2 and negotiating the appropriate deal.

However, its a shame they are still shipping out devices that are clearly defective and did not mention this when I was speaking to them about the upgrade and have wasted my valuable time.

I will post how I get on with switching back to SH2.

Best Regards

Peter

Thknkbroadband, showing switch over from SH2 to SH3Ping to www.bbc.co.uk 8am 22/04/2017 (times in ms)Local ping plot to SH3 (times in ms)Local ping plot to Asus Router (times in ms)

[itinfocus]

Personally what I'd like to hear is the following:

1) That they are aware of the situation

2) Dedicated to working with the manufacturer and Intel to resolve.

3) Progress on at least releasing the current GA firmware from Arris (this has been made available to other TG2492LG users). Even a beta for the customers most seriously impacted would be a start.

[itinfocus]

4) A commitment to supply the working hub 2 to any customer that requests one rather than forcing us to use a device that won't work for our requirements.

[SCA1972]

---

@itinfocus wrote:

Personally what I'd like to hear is the following:

1) That they are aware of the situation

2) Dedicated to working with the manufacturer and Intel to resolve.

3) Progress on at least releasing the current GA firmware from Arris (this has been made available to other TG2492LG users). Even a beta for the customers most seriously impacted would be a start.

---

http://www.ispreview.co.uk/index.php/2017/03/virgin-media-prep-firmware-fix-superhub-3-latency-packe...

______________________
Scott

Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong  If my answer solves your problem please mark it as helpful as it may help others
My setup: Vivid 200 Optical fibre with Hub 3 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.

[itinfocus]

I was aware of the linked article but the single line boilerplate response is woefully inadequate.

To begin with it's at a single source. From an unnamed spokesperson who is most likely in PR.

The substantive portion on the article, in terms of resolution, is entirely the authors speculation.

For such a serious and ongoing issue why do Virgin continue to ignore direct communication with their customers via the community site?

I have read every post on this and many similar threads on the forum and the response is always to ignore or obfuscate. If they are committed to a resolution, actual engagement with the customer base is the only way to truly understand our issues and upstream them to the OEM.

I understand that virgin are beholden to Arris and Intel for the ultimate fix, if any is possible. Still can't understand why they can not be more responsive with items such as the latest firmware. This is not unreasonable, other MSOs have done this and whilst not perfect it's still in Arris' own words 'light years ahead'

The very nature of the bug causes virgins highest plan customers the most significant issues. Surely even the bean counters can see taking a small hit by issuing a more reliable modem temporarily is better than loosing customers in the longer term.

[Peter_JS]

Quick update:

- VM customer help was very polite.

- The chap (first line I guess) was not aware of the problem.

- however after putting me on hold and conferring with colleges, he was able to agree to send me out a SH2ac.

Apparently my old SH2 will not do my 200G package, but this will. Anyone got a SH2ac, and can confirm its ok in modem mode with latency?

Thanks in advance

Peter

[boltedenergy]

---

@Peter_JS wrote:

Quick update:

- VM customer help was very polite.

- The chap (first line I guess) was not aware of the problem.

- however after putting me on hold and conferring with colleges, he was able to agree to send me out a SH2ac.

Apparently my old SH2 will not do my 200G package, but this will. Anyone got a SH2ac, and can confirm its ok in modem mode with latency?

Thanks in advance

Peter

---

Hi Peter,

Thank you for your detailed post, I'm not sure what level of VM staff take a look at the forum directly and if they do if they are choosing to ignore certain subjects i.e. this one. It could also be they are not allowed to comment for legal reasons but whatever the case is, its really bad form to not communicate to your customer when your business is in essence about communications. 

In answer to your question everyone that has managed to go back to the SH2ac does not have the latency issues as far as I know.

[Peter_JS]

Answered my own question.
Seems SH2ac is the answer for now.
http://community.virginmedia.com/t5/Networking-and-WiFi/HUB-3-upgrade-has-drastically-increased-late...

[Peter_JS]

Thanks - our posts crossed.

[itinfocus]

From a technical perspective there is no issue with a 2AC supporting the 200/20G package.

The hub 2ac has a DOCSIS 3 8x4 modem that is capable of delivering just over 300 down and 100 up. However for their own reasons Virgin have decided not to support this modem on that package.

Do you plan on live streaming your gaming sessions? Only ask this as it's about the only sensible reason for a gamer choosing this package. Unless of course you have other non gamer heavy upload requirements such as cloud backup / video conferencing.

If you are just looking for standard web, streaming (iPlayer, Netflix etc) and online gaming experiences the standard vivid 200 is probably the better option.

With this package you can use any of the hub 2 devices and your online gaming and everything will be much better.

The one caveat to this is if you are in ha heavily over subscribed area when the extra channels available can help.