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]

[Drewley]

@mrfreeman the ip addresses in the DDoS network would just get null routed at VM's network edge eventually (i'd hope).

So really it's just a game of how large their network is, and what network detection / controls VM have in place.

If a single customer was to be targeted persistently, it's likely the attacker would have sufficient bandwidth at their disposal to saturate a 300mbit connection no problem, rendering the SH3 DoS vulnerability fairly moot.

All that said, it's still a shambles and should be fixed I agree.

[qpop]

Having posted previously and having made 3 attempts to replace sh3 with sh2ac (all three posted a sh3 to me), making a complaint to CEO and having (utterly useless) executive complaints person call out an engineer who apologetically confirmed local stock of ac2 was non existent, I had resigned myself to my fate.

I have followed this thread regardless hoping for some news.

That said, I received a price rise letter last week, and in typical virgin style was misinformed twice in a row as to whether I had the right to cancel penalty-free.

Eventually I got through to retentions, who didn't understand the difference between speed, latency and usage ("but Mr qpop, you download 700gb a month on average so there is no problem with latency"), and had no method to get a 2ac out to me (other than offering a call back from "priority support"), I gave my 28 days notice and will move back to a much slower (76 Vs 200) connection that actually works as expected!

[nallar]

The problem here isn't whether or not a single residential customer could be knocked offline.

The problem is that an attacker with 1gbps of bandwidth can take 1000 customers offline.

[wotusaw]

qpop wrote:

"Having posted previously and having made 3 attempts to replace sh3 with sh2ac (all three posted a sh3 to me), making a complaint to CEO and having (utterly useless) executive complaints person call out an engineer who apologetically confirmed local stock of ac2 was non existent, I had resigned myself to my fate.

I have followed this thread regardless hoping for some news.

That said, I received a price rise letter last week, and in typical virgin style was misinformed twice in a row as to whether I had the right to cancel penalty-free.

Eventually I got through to retentions, who didn't understand the difference between speed, latency and usage ("but Mr qpop, you download 700gb a month on average so there is no problem with latency"), and had no method to get a 2ac out to me (other than offering a call back from "priority support"), I gave my 28 days notice and will move back to a much slower (76 Vs 200) connection that actually works as expected!"

To qpop..

Can you come back and let us all know about the new connection. Is it better than Virgin for gaming etc? Even though it is 76mb rather than 200mb. I'd be very interested to know as I'm sure now alot of others on here would also be very interested.

Thanks in anticipation.

[Spitfire16]

Had a chat to the complaints team re my complain  to CEO Office about getting a Hub 2AC , was told this isn't possible now

Was told to post on the forums so a VM Staffer could look into it?

Try Modem mode to Reduce Latency (Won't Work)

The person I spoke to didn't know of any Firmware update around the corner , I told him a user had been advised Q7 2017 , Couldn't confirm or deny it

There actively moving people over to the Hub 3 as there doing away with copper telephone lines and moving everyone onto VOIP service in the next 18 months

[Drewley]

@Spitfire16

Unless they provide everyone with battery backup units too, they wont do away with the copper lines, as by law the phone has to function to contact emergency services in the event of a power failure.

[Spitfire16]

@Drewley

My point exactly!

it seems 2nd support don't want to help , i said people are sent 2AC , his reply was it's not possible now , was stopped some time ago(March?!?!) yet people have been getting them as early as last week.

I'm now to document my "Fault" on the forums using modem mode and let the form team diagnose 

[Drewley]

@Spitfire16

I'd try the CICAS route as others have suggested

[rio_w]

If you live in Central London/Swindon try Relish they do 50/250Mbps and 1Gbps broadband download speeds. They do also wireless 4G broadband. 

https://www1.relish.net/home-fibre

Just putting it out there for anyone thinking of another provider.

[RidingTheFlow]

---

@Drewley wrote:

@mrfreeman the ip addresses in the DDoS network would just get null routed at VM's network edge eventually (i'd hope).

So really it's just a game of how large their network is, and what network detection / controls VM have in place.

If a single customer was to be targeted persistently, it's likely the attacker would have sufficient bandwidth at their disposal to saturate a 300mbit connection no problem, rendering the SH3 DoS vulnerability fairly moot.

All that said, it's still a shambles and should be fixed I agree.

---

Do you realise that to bring SH3 completely offline, you just need 200Kbps of bandwidth?

You don't need "Distributed"DOS for this. Anybody with *home connection* can do this - I mean, who doesn't have 200Kbps of upload anyway?

For routers without vulnerability, yes, you will need somebody with 300Mbit upload - and you will need either botnet or somebody with massive upload capacity - unlikely they will just target random persons.

With SH3 - bah, you are at mercy of any kid who download a script and knows your IP.

Also since datastream is so low, unlikely it will be flagged as suspicious (not that VM has any DDoS detection for home users anyway). Also you won't know that you are being attacked in first place (unless attacker tells you about it) - you internet connection just will stop working or be very slow - it will look somewhat like high utilisation (only that Virgin Media will insist everything is ok from their side).

Don't know about you, but I'd be pretty miffed about any kid who knows my IP to be able easily to bring down my internet from their residential connection.