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]

[robbiekhan]

I was told last month that the utilisation fix for Fareham (area 20) was happening mid April. Well it’s now coming up to the end of April and still no fix. Looks like it’s time to call VM and make sure my poor quality of service discount remains applied for another month or however long it will be taking.

[Guybrush85]

I guess there's some solace in knowing we're not alone with this.

As for the above comment, I have no idea what that has to do with the topic and suggest you create a thread to discuss that if you haven't already.

[Peter_JS]

@avro698

Yep, VM would not support 152, even thought the device does it. I don't think they have that config option available to them. Might be the older devices are less efficient, i.e. support less QAM so VM do not want to use too many channels. So I'm back on 100/6.... so while I really really want more UL, I'd rather have less and very good responsiveness any day of the week, and all is now good as a result in the household.

I do not think this device can be fixed. Took me a while to try and explain this as politely as I could. Ended up talking to about 8 people, bouncing around between techies and customer service before getting a result. Be patient, they are only human and do their jobs the best they can. Its not the support staff's decision on what devices to support.

Regarding the graphs not showing, I noticed the image is replaced with a link to a "unmoderated" image, so someone is having to approve them.

Bad reading over on dslreports, thanks for links.

Peter

[qpop]

Very frustrating fourth call today with Virgin who are saying now that absolutely no way they will be able to send out a 2AC.

This particular rep and their manager also stated that they believe categorically that as long as the sync speed is 200mbps they are delivering what should be expected, and therefore they don't consider high latency to be an issue.

Any thoughts on this?

[robbiekhan]

@Butler85 - It was actually a reply for the other thread, posted here by mistake (multiple tabs).

[Peter_JS]

@qpop

Hmm - that's a dodgy statement from them

The irony is they sell a "gamer" package with that modem. Gaming is all about latency and packet reliability and not b/w (unless you're hosting).

FYI, I did a long ping (300 seconds) to the beeb on my SH1.

Results:

--- www.bbc.net.uk ping statistics ---
300 packets transmitted, 300 received, 0% packet loss, time 299396ms
rtt min/avg/max/mdev = 13.696/15.022/26.955/1.494 ms

If you compare with my results on page 35, it seems like the SH3 does add circa 5 to 6 ms, so even without the latency spikes, this makes it not fit for purpose, or at worst a serious downgrade for gamers. Facts speak for themselves.

Best

Peter

[qpop]

This afternoon I'm going to write a complaint to their CEO's office. I will paste the text here and update you all with how I am getting on.

[AndyN131]

Make sure you send a link to this thread in the letter.

[Guybrush85]

---

@robbiekhan wrote:
@Butler85 - It was actually a reply for the other thread, posted here by mistake (multiple tabs).

---

Ahhh, happens to the best of us. 

[Peter_JS]

Sorry...typo
>> If you compare with my results on page 35

I should have written

"Should be If you compare with my results on page 53"