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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

wotusaw
Superfast

Petelunn wrote:

"We are all angry but Virgin and Intel really don't seem to care

Upgraded to Vivid 200 Gamer as my son was doing well in an overwatch team but since upgrading he has had to stop playing with them as the latency is soooo bad. I've also had to stop raiding with my Warcraft guild as I've gone from one of the top DPS in the guild to one of the lowest. People with lower gear then my character do better dps.

I have four sons at home all who game and so do I, they also stream a lot of content so the 200mbps is great but I'm seriously thinking of leaving if I see a price increase. Only been on Gamer and therefore changed to the Hub 3 for a few months so unless they increase prices I can't leave and am stuck with this crappy hub.

Can get Sky Fibre at 76mbps in my area and its looking very attractive."

 

Like you I have a son who's gaming, like my own has been ruined by this fiasco. 

I make fun of it but I'm actually really really ****** off.

So I know where you are coming from.

We've all been sold a lemon.,,,that includes Virgin and the rest.

By the way, I reboot this pile of **** every day to try and improve it's pathetic ******** performance. Apparently it gets  worse, wonky after 22 hours of use. This may or may not be true but I do it anyway.

Anyway, November will be interesting.Smiley Wink

Fwiw, the Puma 7 modem with or without Docsis 3.1 is greatly improved over the Puma 6 modems.  The various protocol latencies that are observed in the Puma 6 modems are not present in the Puma 7 modem.  That is for the Hitron CODA-4582 on the Rogers network in Canada.   Having said that, the latest firmware version has introduced a modem to CMTS ICMP latency that wasn't present in previous firmware versions.  This appear to be restricted to the modem to CMTS ICMP ping only, with no observable effect (at least not detected) on any other protocols or destinations beyond the CMTS.  None the less, this requires attention from Rogers, Hitron and Intel to sort out. Running Docsis 3.1 downstream, there is an absolute improvement in downstream and upstream data rates.  I didn't expect to see the upstream improvement but the data rates went from roughly 30 Mb/s during the mid day hours, 50 Mb/s at night, to 55 to 58 Mb/s throughout the day.   UDP throughput performance (data rate) without losses has also improved to the point where the modem is probably better than many routers, so in terms of straight throughput consideration, running the modem might be a better idea.  The exception will be for high end routers such as a PfSense, OpenSense, Sophos type of router.  Users with routers will have to run their own tests to determine what is better on their ISP, considering the modem and router models ..... router or no router, that is the question.  Routers will have much better user controls than you would ever see in a modem, but, that might not matter if you run a simple network and are interested in throughput rather than router functions.  

On my list of things to do is to post some screen shots, Puma 6 versus Puma 7 on the DSLReports site, just haven't found the time lately to do that. 

Here are a a few screen shots that show the Puma 6 IPV6 latency to the CMTS, taken in June 2016, followed by the Puma 7 switchover from Docsis 3.0 to 3.1 taken in March 2017.  The Puma 7 shot still shows high evening latency running Docsis 3.0, which basically disappeared when 3.1 was enabled. 

 

Puma 6 IPV6 ICMP 32 channel latency to the CMTSPuma 6 IPV6 ICMP 32 channel latency to the CMTS

Didn't expect such a detailed answer! Thanks, Data
--------------------------------------------------------
Look behind you, a three-headed monkey

grrr, short timeframes to edit a post.  That needs to be corrected.... hello mods ...

Ok, continuing with the task at hand.

First plot below:  Puma 7 prior to switching to Docsis 3.1.  On the left of the center latency spike, the day before my CMTS starts to switch to 3.1, so, still runnnig Docsis 3.0 with its high latency during the evening.  On the right of the center latency spike, probably the day that some users switch over to Docsis 3.1.  I wasn't one of them, but, there is still a remarkable drop in evening latency. 

 

Still on Docsis 3.0, left and right of spikeStill on Docsis 3.0, left and right of spike

 

 

Second plot below:  the day of the change.  On the left of the central packet loss indication, Docsis 3.0, on the right of the packet loss spike, Docsis 3.1.  Flat line except for one spike during the entire day.  

Docsis 3.0 on the left, Docsis 3.1 on the rightDocsis 3.0 on the left, Docsis 3.1 on the right


@mbulliva wrote:

I thought the Virgin Business Broadband Hitron modem which has the April 2017 firmware fix does improve latency a bit, certainly with synthetic benchmarks.

I have not seen a proper confirmation of that (like BQM graphs). Anyway improving it "a bit" won't cut it, it will need a lot of improvement to be passable.

Where are the stats for min/max in your plots ? This is CRITICAL as you pointed out on DSLR that Pingplotter averages out and does not show the spikes in long term plots.. Im not quite sure I see the dramatic drops in latency. I see small ones. However I would need to see the max statistics showing the spikes.

Als in any plots your post make sure to also show the jitter chart along with the full stats..

Intel has a official post on DSLR.. The Puma 7 has the issues and has never had a firmware patch related to them released. This is confirmed.

A email I sent on this subject that covers the post:

________________________________________

So.. Intel decided to provide a official update via the thread. No doubt all my pressure via MITRE had some effect..

What they said was that we are months to years away from any fix or CVE. They explained this in very slippery wording.. I picked it all apart in my counter post. https://www.dslreports.com/forum/r31122204-SB6190-Puma6-TCP-UDP-Network-Latency-Issue-Discussion~sta...

 They also said the Puma 7 does not have a fix worked out yet even at Intel so far.

This leaves millions of Puma 5/6/7 users exposed to the DoS and performance issues for months to years to come yet.

This whole debacle is completely out of control and incredibly annoying for end users like the poor souls on Virgin Media who cannot go buy a modem to prevent attack or fix performance issues.

Intel's confirmed official spokesman is ChipHeadx86

https://www.dslreports.com/forum/r31122204-SB6190-Puma6-TCP-UDP-Network-Latency-Issue-Discussion~sta...

 

Lets see a 1hr plot setup like this one. 1 hour width. TCP, 10hz at least, same scale settings.. It can be port 80 to google. Then we can compare a Puma 6 VS Puma 7

DNSPlot1hrX6190

This effects the Puma 7 and no patch has been issued by Intel yet. https://www.theregister.co.uk/2017/04/27/intel_puma6_chipset_trivial_to_dos/

My point here is that the Puma 7 is just as plagued as the Puma 6. Is it less plagued ? By performance issues ? maybe. Does DOCSIS 3.1 help VS DOCSIS 3.0 ? Maybe. But its still nowhere near a Broadcom solution  and the Puma 7 can be taken offline with a whisper of bytes.

ALL Pumas are sick. So far there is no proven cure. Any cure is months to years away, if there is a cure possible.

 

 

 

I did a video to show the evil averaging ping plotter does at different graph window sizes.. This also shows the spike more viscerally. Better to seem them occur live..