Slow Cable Modems - Everyone Please Read

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Slow Cable Modems - Everyone Please Read

I am a Broadcom employee. Broadcom makes cable modem chipsets. Some of these chipsets have a slight design flaw. I am not at liberty to divulge any technical details. However, I can tell you that using a cable modem containing one of these chipsets with your Mac will result in slow internet speeds. Apple is not at fault. I'm sorry to say that fixing these design flaws, which only affect Mac users is not a priority at this time.

I am a Mac user myself and am just as frustrated as you are with incompatible products. This is why I am coming forward and informing you of this problem with our products. Our chipsets are used in almost all of the most popular cable modems. I am including a partial list of the most recent and popular cable modems that use our chipsets which have this problem. I am unable to find any information about older and less popular cable modems. Please understand that I can not and will not divulge any more information. Thank you.

All Linksys Cable Modems
All Motorola Cable Modems except for the SB5120
All Scientific Atlanta Cable Modems

Posted on Aug 25, 2006 12:07 PM

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Answer 1

BDAqua

Level 10

250,259 points

Aug 25, 2006 12:25 PM in response to Broadcom

Thanks.:-)

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Answer 2

rpg

Level 1

15 points

Aug 25, 2006 9:56 PM in response to Broadcom

All Linksys Cable Modems
All Motorola Cable Modems except for the SB5120
All Scientific Atlanta Cable Modems

Is this a joke

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Answer 3

Broadcom Author

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Aug 25, 2006 10:16 PM in response to rpg

Is this a joke

Absolutely not. As I said, cable modems that use Broadcom chipsets exhibit slow speeds when used with Macs. I've experienced this personally and so have many other Mac users.

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Answer 4

Aug 26, 2006 7:10 AM in response to Broadcom

That's messed up.
Seems like there should be a hack to tell your modem you are a Windows box...

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Answer 5

Broadcom Author

Level 1

0 points

Aug 26, 2006 11:26 AM in response to Gnarlodious

That's messed up.
Seems like there should be a hack to tell your modem
you are a Windows box...

I'm afraid it's much more complicated that. Some modem manufacturers have managed to work around the problem with a firmware update. The modem manufacturers are the ones who alerted us to the problem when all of their Mac customers began screaming at them.

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Answer 6

Aug 26, 2006 12:57 PM in response to Broadcom

I just got cable today in my new place and decided to buy a used modem and it turns out that its a scientific atlanta inc. modem. Do you know if they have an update to fix this? i searched their website but turned up no results.

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Answer 7

Broadcom Author

Level 1

0 points

Aug 26, 2006 1:41 PM in response to Daryl Armour

Do you know if they have an update to fix this?

Are you having speed problems? If not, don't worry about it.

Otherwise, you will save yourself a lot of headaches by just buying a D-Link modem down at your local Best Buy. Your cable company has to update your modem's firmware. I don't know if Scientific Atlanta has bothered to work around the problem with our chipsets in their firmware or not. Seeing as how they are owned by Cisco, which also owns Linksys I wouldn't count on it. The Linksys and Scientific Atlanta modems are the ones that Mac users have the most problems with.

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Answer 8

tbux

Level 4

1,691 points

Aug 27, 2006 11:30 AM in response to Broadcom

You mentioned the Motorola SB5120, any chance the SBV5120 is OK ?

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Answer 9

Broadcom Author

Level 1

0 points

Aug 27, 2006 12:03 PM in response to tbux

any chance the SBV5120 is OK ?

I think the SBV5120 is just an SB5120 with integrated VOIP. Be aware that the SB5120 autonegotiates ethernet at half duplex with a Mac or AirPort. Your speeds will be halved unless you force full duplex on the connected Mac or AirPort.

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Answer 10

typ993

Level 1

36 points

Aug 28, 2006 9:55 AM in response to Broadcom

Does this flaw apply only to Macs connected directly to the cable modem or does it apply as well to situations where the cable modem is connected to a router, then the Mac is connected to the router?

I have seemingly slow connection speeds in the latter situation with my Mac (not my PC) and I'm using a Motorola Surfboard (not the 5120).

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Answer 11

fragmore

Level 3

661 points

Aug 28, 2006 10:29 AM in response to Broadcom

Get a Motorola surfboard. They are the best and completely reliable.

Motorola support cannot be beat.

Unless, of course, you enjoy playing with an inferior modem that requires constant tweaking rather than going online.

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Answer 12

Broadcom Author

Level 1

0 points

Aug 28, 2006 1:48 PM in response to typ993

I have seemingly slow connection speeds in the latter
situation with my Mac (not my PC) and I'm using a
Motorola Surfboard (not the 5120).

It's the modem. Read all of my other posts and you should know what to do.

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Answer 13

Aug 29, 2006 7:28 PM in response to fragmore

Maybe Broadcom can answer the question as to why the Cable modems are slower with Macs with cable modems that do not have TurboDOX.

I have spent hours on numerous forums reading many users complaints and many users solutions from changing DNS to using certain modems.

What I have found is this. All and EVERY cable modem that people have references as working at full speeds on a Mac had 1 thing in common. This 1 this is TurboDOX. I have just completed about four locations where the Macs were slow with Comcast Cable modems. The latest being today with a new installation with a new SB5101 modem. I had the client go and buy a new SB5120 instead. The speed with the 5101 was 2-3Mbps and the speed with the 5120 was 18Mbps!!! yes, 18.

So the question is Why does TurboDOX make a difference with the Mac and not the PC????
Also, another thing to note is that some routers cap the WAN to LAN interface at 6Mbps. For example, the COMSUMER grade Netgear routers (usually the silver plastic ones) are capped at 6, however the Business class routers have varying WAN to LAN speeds ranging from 15Mbps to over 50Mbps.
Our setups for residential clients include either the Netgear FVS114P or the FWG114P VPN Firewall Routers. I have had no issues with Macs being slow with either of these routers and a Motorola SB5120.
FWIW.
And about the Design Flaw theory, Why did this speed issue just start appearing recently? I saw a site test fine at 6Mbps when it first was installed then recently when we went back to do some work find it testing between 1-3Mbps. Just Odd.

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Answer 14

tsteph5

Level 1

45 points

Aug 29, 2006 7:59 PM in response to Karl Wojcik

what is turbo dox and how can you tell if a modem has it. i have the linksys wcg200. and i also have slower speeds on my mac than my pc.

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Answer 15

Aug 29, 2006 8:19 PM in response to tsteph5

what is turbo dox and how can you tell if a modem has
it. i have the linksys wcg200. and i also have
slower speeds on my mac than my pc.

From Motorola's description of the SB5120 Cable Modem:

Enhanced with TurboDOX™ Bandwidth Optimization Software: can further boost download speeds by up to 20 times*

Now, to resolve the Mac speed issue, Get a new Cable Modem that has a TI Chipset and DOCSIS 2.0 (May or may not need TurboDOX, I havn't figured that out completly yet) Here are some of my experiences:

Linksys WCG200 - 1.5Mbps => Changed to an SB5120 with a Netgear FWG114P router - 12 to 16Mbps.

Motorola SB5101 with a Netgear FVS114 - 3Mbps => Changed to an SB5120 with the same router - 18Mbps

Motorola SB4220 (TI Chipset) with a Netgear FWG114P router - 8Mbps

Motorola SB5120 with a Netgear FVS338 router - 16-20Mbps

- Just trying to help.

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