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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 wrote:

I'm pretty sure someone sooner or later will take Virgin to court regardless whether they stand a good chance of winning or not.

Customers are very angry about this and Virgin with their refusal to keep us well informed about the whole sad sorry affair are just making it worse.

The 'advert' alone makes my blood boil every time I see it!! 

Virgin should have checked the modem BEFORE they gave it out to customers to see if it was fit for purpose.

It may be fit for their purpose but it's certainly not fit for the customers who pay them as can be seen from the length of this post.

Smugly repeating that they are providing what's in the contract just rubs salt into the wound and it will all come back on Virgin when it's contract renewal time.Smiley Mad


As has been mentioned, during testing there were less downstream channels, in this scenario the modem did not show any issues, its only once the upstream channel count was increased that this problem was shown to exist, so when it was tested it WAS fit for purpose, at the end of the day VM are a victim of this issue as much as end users, threatening them with legal action won't speed the process up, it won't force them to allow 3rd party modems on their network, it won't force them to release a hub4 any sooner than they would have, literally the only thing you're likely to get out of it is an offer to leave without penalty, as for VM not informing us, what exactly would you have them say, if i remember correctly there is a post on here somewhere that states they are aware of the issue and that intel are working on a fix, what else could they even say apart from copy and pasting "A fix is still in development" every month in to a thread, i personally won't be leaving over this and i imagine a majority of their customer base won't either and i'm not even still in a minimum term contract so i can just up and leave at any time


@shanematthews wrote:

As has been mentioned, during testing there were less downstream channels, in this scenario the modem did not show any issues,
I disagree. The modem showed latency issues from the 1st hour I used it during the SuperUser trial. My notes say I reported the latency issue on the 24th September 2015, 2 weeks before the public trial started. 
its only once the upstream channel count was increased that this problem was shown to exist,
It's the increase in downstreams that mainly affects it. Most of us were on 2 upstreams then and still are now. I was on 16 downstreams then, so it was quite noticeable.
so when it was tested it WAS fit for purpose,
Were you even in the trials? That was not the consensus.
at the end of the day VM are a victim of this issue as much as end users,
Cable Operators are not stupid. They have labs that can test the full 24 downstreams and monitor results in much more detail than we can.
threatening them with legal action won't speed the process up, it won't force them to allow 3rd party modems on their network, it won't force them to release a hub4 any sooner than they would have, literally the only thing you're likely to get out of it is an offer to leave without penalty,
That I agree with.

 


@MUD_Wizard wrote:

@shanematthews wrote:

its only once the upstream channel count was increased that this problem was shown to exist,
It's the increase in downstreams that mainly affects it. Most of us were on 2 upstreams then and still are now. I was on 16 downstreams then, so it was quite noticeable.

 

Totally agree with @MUD_Wizard here, I have seen my BQM get worse every time I was given more downstream channels, in the past 9 months I have gone from:

8 downstream channels to 16 downstream channels (STILL ONLY 2 UPSTREAM CHANNELS 16 qam Smiley Sad)

16 downstream channels to 20 downstream channels (STILL ONLY 2 UPSTREAM CHANNELS 16 qam Smiley Sad)

20 downstream channels to 24 downstream channels (STILL ONLY 2 UPSTREAM CHANNELS 16 qam Smiley Sad)

So I am now sitting at 24 downstream and just 2 upstream channels running on the old 16 qam just look at the state of my BQM and people wonder why I get salty when I see VM advertisements Smiley Mad

I just expect to get what I am paying for nothing more nothing less VM cannot go around advertising a gaming tier and then supply it with 200 ms latency

> threatening them with legal action won't speed the process up, it won't force them to allow 3rd party modems on their network, it won't force them to release a hub4 any sooner than they would have, literally the only thing you're likely to get out of it is an offer to leave without penalty,

Almost agreed. I don't expect it would solve the problem for yourself or anyone, but I do expect you'd get an early termination and a full refund. At this point there is no solution to the problem for most people - Hub 2ACs are not being sent out from stock, engineers have been told to return any 2ACs they have. New packages will require the hub 3.

In the US the FCC require third party modems to be allowed after a reasonable amount of testing. Charter lost a lawsuit over this and now allow third party modems. Unfortunately there is no such rule in the UK so that will not happen.


@nallar wrote:
Hub 2ACs are not being sent out from stock, engineers have been told to return any 2ACs they have. New packages will require the hub 3.

I still have a hub 2ac but using it = even slower speeds due to only having 8 downstream channels 

In the US the FCC require third party modems to be allowed after a reasonable amount of testing. Charter lost a lawsuit over this and now allow third party modems. Unfortunately there is no such rule in the UK so that will not happen.


I would happily buy my own modem and put an end to this puma 6 nightmare however like you see VM will never allow this to happen.....

 

Yeah i typed upstream instead of downstream, thats what happens when you write posts while half asleep 😛

 


@nallar wrote:
> threatening them with legal action won't speed the process up, it won't force them to allow 3rd party modems on their network, it won't force them to release a hub4 any sooner than they would have, literally the only thing you're likely to get out of it is an offer to leave without penalty,

Almost agreed. I don't expect it would solve the problem for yourself or anyone, but I do expect you'd get an early termination and a full refund. At this point there is no solution to the problem for most people - Hub 2ACs are not being sent out from stock, engineers have been told to return any 2ACs they have. New packages will require the hub 3.

In the US the FCC require third party modems to be allowed after a reasonable amount of testing. Charter lost a lawsuit over this and now allow third party modems. Unfortunately there is no such rule in the UK so that will not happen.

You won't get a refund, your connection is working, you have access to the internet, they have provided what they are contractually obligated to provide, US policies are down to them, they aren't able to enforce this upon VM, VM having a complete monopoly on the cable market here means there isn't as much of a market for alternative devices, ADSL is over saturated and due to how it works its trivial to use a 3rd party device, you don't even need to contact them and tell them 😛

As i've said, the very best you could hope for out of a complaint is an offer of early termination without penalty, thats unlikely to be on the table should you start taking them to court and making idle threats about suing them, raise a complaint and leave if you're unhappy, nothing is going to be fixed overnight and its likely to take months before the FW fix filters down or we get a hub4

@deviousiphone

Here's a direct comparison of my SH2ac and Hub 3 tested on the same VM line just now, minutes apart:

SH2AC - 8 downstreams obviously (router mode):

Screenshot from 2017-05-28 16-24-34.png

 

Hub 3 with 20 downstreams (router mode):

Screenshot from 2017-05-28 16-25-04.png

Yeh I have tested it myself in such a fashion, hopefully a firmware fix will be out in the next few months

What concerns me about this, is that the superusers have openly admitted they reported this issue when testing the Hub 3 and still they didn't respond to it, yet deployed it on a massive scale and upset so many people, they could of avoided this if they wanted too


@deviousiphone wrote:
What concerns me about this, is that the superusers have openly admitted they reported this issue when testing the Hub 3 and still they didn't respond to it, yet deployed it on a massive scale and upset so many people, they could of avoided this if they wanted too

Yeah but then what about all the areas with congestion because of being limited to 8 downstreams?

Do they stop all network expansion plans?

Not launch any new higher tiers?

Sharing more downstreams - 16, 20, 24 does improve bandwidth/speed performance.

There had to be a middle ground somewhere. Not how they did it of course.