Intel Atom-based Puma 6 Modem Chipset has Severe Latency Issues, Many Cable Modems Affected

[R-T-B]

Sometimes as a news reporter, a story drops right into your lap. That was the case with me and my latest experience with my ISP rented modem, which I recently upgraded to support higher speeds.

The modem I got was based on the Puma 6 chipset, which is an Atom based chipset from Intel. I immediately noticed a more sluggish web experience, despite the bandwidth nearly doubling (going from 8 downstream pipes to 24 will do that). I began to google this issue, and came up with a much-underreported issue from a thread on dslreports.com where the dedicated members there have extensively documented the issues with the Puma 6 chipset, and Intel's apparent inability to patch them.




The issue appears to be Intel's insistence on doing on the data processing of the mathematical channel separation (Full Spectrum Frequency Capture, which this modem utilizes, is a very mathematically intense operation) on a weak Atom CPU. The CPU bogs down under load, resulting in frequent latency spikes up to 250ms (that's like going around the globe twice, for reference). Intel for its part has put out firmware patches, but two fixes later and they are apparently unable to correct this issue beyond making ICMP work. TCP/UDP is still a mess, and guess what? That's what everyone uses.

One would hope they are still looking at firmware fixes, but the situation seems dire. There is talk of class-action lawsuits brewing all over the dslreports.com forums, and this does not seem to be idle chatter given the fact that a major modem manufacturer, Arris, has invested heavily in this chipset (Arris for its part, has already filed a lawsuit).

This chipset is a very widely used chipset in cable modems, so if you've been noticing latency in your connection, you'd best test if it uses the Puma 6 chipset. Ironically, the best way to test it is via a performance test cooked up at dslreports.com: It's performance is so consistently bad you can actually detect the chipset via its performance metrics. It is worth noting, nearly all >8 downstream pipe modems rented from comcast with voice function (something they push heavily), and many even without the voice function include the Puma 6 chipset.

As for my personal experience, I exchanged for a customer owned-modem: A Netgear CM600 (Broadcom Chipset). About darn time.

See the test at this link, and stay tuned for more on this developing story. Your local TPU-newsposter is on it.

UPDATE: It would seem the atom-core is not the issue, as the arm core does the packet processing as some users pointed out. Regardless, the chipset as a whole appears to be faulty, and it is all Intel IP.

http://www.dslreports.com/tools/puma6

View at TechPowerUp Main Site

 

[ASharp]

Surprised to see this mentioned here to be honest. Being in Canada, most if not all of the DOCSIS 3.0 modems available from the major cable internet providers here use the Puma 6 chipset. In my case, I have the Hitron CDA3. Since we can only use approved modem models, there isn't really anything we can do here to avoid the issue.

With any luck hopefully we'll get a fix for this but after well over a year, we're not any closer to a solution. I'm not holding my breath.

 

[R-T-B]

Surprised to see this mentioned here to be honest.

I'm surprised at how little coverage this issue has frankly. It is appropriate for here anyways given it's strongest impact would be in online gaming, and we are largely a PC gaming hardware site.

 

[TheGuruStud]

This is what they get for not using arm.

 

[Melvis]

I'm surprised at how little coverage this issue has frankly. It is appropriate for here anyways given it's strongest impact would be in online gaming, and we are largely a PC gaming hardware site.

Its Intel, they cover up as much as they can so they dont look bad. Nothing new really. But thanks for reporting this

 

[ASharp]

I'm surprised at how little coverage this issue has frankly. It is appropriate for here anyways given it's strongest impact would be in online gaming, and we are largely a PC gaming hardware site.

I guess I'm more so surprised that any tech publications I frequent actually wrote anything about it. It's a pretty big problem but this is the first time I've seen anyone outside of DSLR mention it.

 

[Squishy Tia]

This is what they get for not using arm.

Actually, there is an ARM CPU in the Puma 6 architecture. There is both an ARM and Intel CPU. The ARM CPU is what is active for all modems. The Intel CPU appears to only be active on the gateway (combo modem/router) models. That said, the Puma 6 IP is entirely Intel's, and thus their responsibility to fix.

 

[TheGuruStud]

Actually, there is an ARM CPU in the Puma 6 architecture. There is both an ARM and Intel CPU. The ARM CPU is what is active for all modems. The Intel CPU appears to only be active on the gateway (combo modem/router) models. That said, the Puma 6 IP is entirely Intel's, and thus their responsibility to fix.

Which makes it even dumber. There was never a reason to use x86. Intel must have gave them away, literally.

 

[Squishy Tia]

Which makes it even dumber. There was never a reason to use x86. Intel must have gave them away, literally.

Being that the ARM is in control of the modem's interface, the Atom CPU would be in control of the router portion of a gateway. The reason the Atom is there in the non-gateway modems is because Intel chose to use a single SKU for both types of devices, but to shut down the Atom CPU on non-gateway devices. Also, the ARM CPU appears to have severe latency issues under heavy load and/or bonded to >24 channels. In the latter case, baseline latency doubles.

 

[TheGuruStud]

Being that the ARM is in control of the modem's interface, the Atom CPU would be in control of the router portion of a gateway. The reason the Atom is there in the non-gateway modems is because Intel chose to use a single SKU for both types of devices, but to shut down the Atom CPU on non-gateway devices. Also, the ARM CPU appears to have severe latency issues under heavy load and/or bonded to >24 channels. In the latter case, baseline latency doubles.

I used to hit 275 Mb without issue (many connections, too). But...custom firmware...
Higher was possible, but limited to 8 channels

I still don't know why anyone would let x86 in when EVERY router/AP I've seen is arm. Wait, they gave em away lol

 

[Squishy Tia]

I used to hit 275 Mb without issue (many connections, too). But...custom firmware...
Higher was possible, but limited to 8 channels

I still don't know why anyone would let x86 in when EVERY router/AP I've seen is arm. Wait, they gave em away lol

...sigh.

They left the Atoms in place in all devices so they had only one SKU to develop for. I guarantee they weren't given away.

 

[TheGuruStud]

...sigh.

They left the Atoms in place in all devices so they had only one SKU to develop for. I guarantee they weren't given away.

Yes, but you're telling me there wasn't another solution available, so every modem manuf went with puma 6? They did for a reason and I suspect it was basically free chips. Hell, they couldn't give em away in phones. I guess it's time to cram them in something else.

 

[Xzibit]

This was a known issue for awhile IF you were paying attention to it. The solution is to find out which modems are compatible with your ISP. They usually have a certified list on their sites. If your renting it, return it for a Broadcom or Puma 5 chip based modem. If you bought your own and its a Puma 6 then buy a Broadcom or Puma 5 based modem from the compatibility list.

Make sure your replacement handles your speed tier.

 

[Squishy Tia]

Yes, but you're telling me there wasn't another solution available, so every modem manuf went with puma 6? They did for a reason and I suspect it was basically free chips. Hell, they couldn't give em away in phones. I guess it's time to cram them in something else.

If you knew anything about modems and gateways, there was only one 32 channel capable chipset when these came out. That would be Puma 6. Not until Puma 7 and the new Broadcom SoC used in the Netgear CM1000 and Arris SB8200 were there other 32 channel capable chipsets. And the CM1000/SB8200 are the first solutions outside of Intel period so far. Outside of the CM1000/SB8200, the only 32 channel capable devices are Puma based (6 and now 7). All Broadcom solutions max out at 24 channels prior to the CM1000/SB8200.

 

[TheLostSwede]

I still don't know why anyone would let x86 in when EVERY router/AP I've seen is arm. Wait, they gave em away lol

Uhm, actually, most low cost routers use MIPS, not ARM...

 

[librin.so.1]

. Since we can only use approved modem models

What does that even mean?

 

[Derek12]

WOW between this and the Atom c2000 issues

What bad name will Atom get with all this

 

[R0H1T]

And seems like they have a costly class action lawsuit coming their way, at least the modem maker

Intel's buggy Puma 6 chipset earns Arris a gigabit-modem lawsuit

Spoiler

Laggy silicon at heart of broadband boxes lands gateway maker in court

Cable modem maker Arris is facing a class-action suit over its handling of a lag-prone line of cable modems.

The complaint, filed in the Northern California District Court, accuses the vendor of violating four California state consumer protection laws and seeks relief for folks in the Golden State who purchased an Arris SURFboard SB6190 modem since its launch in late 2015.

According to the complaint, Arris violated state laws on misleading advertising and unfair competition, as well as consumer protection and warranty laws, when it advertised and sold the SURFboard cable modems as "gigabit" home internet boxes.

As covered in detail by El Reg in December, the Arris SB6190 was among home gateways using a buggy Intel Puma 6 chipset that was prone to high latency under certain circumstances. This chipset caused the SB6190 – and other DOCSIS 3.0 cable modems using Intel's silicon – to suffer from jittery connectivity that ruined online gaming and other latency-sensitive apps.

While Arris is the only company named in the complaint, it was not the sole vendor to fall victim to the design flaw. Branded boxes offered by Comcast and Virgin Media, as well as modems from Hitron and Compal and network gear from Cisco and Linksys, were all said to use the lag-prone Puma 6 chipset.
Attorneys for named plaintiff Carlos Reyna cited The Register's in-depth coverage in claiming that by failing to ship a fully working product and by not being able to coordinate with ISPs to provide an effective firmware update to remedy the issue, Arris had failed in its obligations to customers.

"By shipping modems with this defect, Arris sold consumer goods that were substantially below the quality generally available in the market, were not fit for the Internet connectivity for which they were generally used, and were not adequately packaged and labeled," the complaint reads.

"Arris also concealed the network latency problem with the Modem through its marketing, advertising, and packaging of the product."

The suit seeks a jury trial to decide damages for Reyna and all other Californians who purchased the SB6190.

Arris declined to comment, citing the matter as pending litigation. Separately, we're told a firmware update for the Puma 6 issue, developed by Intel and Arris, has been sent out to some customers, however it is not a full fix and is considered by affected punters to be incomplete.
Meanwhile, Arris opted for a chipset from Intel's rival Broadcom in its latest gigabit cable modem – the DOCSIS 3.1 SB8200 – that was announced earlier this year. This means Arris snubbed Intel's Puma 7, a DOCSIS 3.1 part and a successor to the buggy Puma 6, for its newest device and went with Broadcom's BCM3390 chip instead.

According to early reviews, it looks like it was a good decision to go with Broadcom. Reviewers online have given the SB8200 a thumbs up.

It is possible Arris switched from Intel's Puma 7 to the Broadcom BCM3390 at short notice for the SB8200 after the Puma 6 scandal blew up. However, due to manufacturing pipelines, it's more likely Arris had the BCM3390 lined up for the SB8200 months before the firmware debacle kicked off – and good thing, too.

WOW between this and the Atom c2000 issues

What bad name will Atom get with all this

Not much, if anything people don't even know what happened with the c2k & this is also a non news for most people who are unaffected, even among the users personally hit by these [insert politically correct euphemism for greedy corporations] they'll go to the hardware vendor. Intel goes scot free, like they always do. The AT front page doesn't even mention this, they didn't cover the precious Atom fiasco either, Intel still have have fans/followers/stooges even among the more reputed tech sites.

 

[EarthDog]

... issue has been out since mid 2016 or so..

Ive had the sb6190 for several months now (was unaware of this issue, lol) and noticed some severe latency issues. Ive been waiting for a patch, but none have come out. Im going to downgrade to the sb6183 which doesnt have the puma based chipset.

 

[Frick]

I assume it's not because the CPU is slow as such, just that it's configured very badly. *Just.*

 

[EarthDog]

I assume it's not because the CPU is slow as such, just that it's configured very badly. *Just.*

correct...its not slow..

...but do you know what that will do with ln2?

Hope you are well Frick.

 

[R-T-B]

... issue has been out since mid 2016 or so..

Yes, but is severely undercovered by the media. I felt it my duty to bring some more attention to this issue as a reporter, especially as it's still an evolving issue.

 

[EarthDog]

Right... wasnt trying to take anything away, just add a point this has been an issue for nearly a year at this point.

 

[R-T-B]

Right... wasnt trying to take anything away, just add a point this has been an issue for nearly a year at this point.

It became a personal issue for me when I bought one, though.

Seriously, it made me aware of the lack of coverage, which I found appalling.

 

[Static~Charge]

I'm surprised at how little coverage this issue has frankly. It is appropriate for here anyways given it's strongest impact would be in online gaming, and we are largely a PC gaming hardware site.

Why your gigabit broadband lags like hell – blame Intel's chipset
Software fix coming after Puma 6 code bug hits Virgin Media, Comcast, Arris and other boxes
3 Dec 2016
https://www.theregister.co.uk/2016/12/03/intel_puma_chipset_firmware_fix/