 TAZ
join:2014-01-03
Tucson, AZ |
to Qumahlin
Re: [Speed] PSA: Slow WiFi on Comcast? May be Comcasts Faultsaid by Qumahlin:You guarantee most won't, yet most users aren't experiencing this issue and in the case of the router that started the thread on DD-WRT that router WORKS FINE until DD-WRT is installed on it....so once again we are back to why is it the manufacturer was able to handle this scenario, yet DD-WRT is not. Or maybe those users wouldn't possibly think "hmm, I wonder if Comcast is setting DSCP to some random value and causing WMM to treat my traffic as low priority?" Linksys isn't the only router maker, and that particular model isn't the only router they make either (maybe some others from them are affected). |
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to Qumahlin
said by Qumahlin:So your answer is that
1. DD-WRT is flawed and is responsing more aggressively that it should
2. Broadcom has an issue with their drivers.
3. The stock firmware of the e1200 and most other routers won't exhibit this issue because they aren't incorrectly aggressively responding to DSCP.
Got it. So we have a firmware issue, a driver issue and then the manufacturers who somehow made sure their stock firmware doesn't have these issues...yet this is comcasts problem to fix. Um no. Once again, comcast can help fix it, but you yourself identified that this is a bug and if the device was performing as expected this bug would not be occuring 1. Yes, but that doesn't mean Comcast is not wrong. 2. Yes, some respond very aggressively to low priority DSCP, however the DSCP marker Comcast is using is only supposed to be used with low priority unimportant traffic. 3. They still respond to the incorrect DSCP, but instead of slowing down aggressively(to save battery) they only lower its priority in relation to other traffic(LAN) which is also a problem. Comcast has a problem, some devices simply don't handle Comcasts problem as well as others. Why should Comcast be marking traffic as low priority unless it truly is low priority? |
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 MoracCat god
join:2001-08-30
Riverside, NJ |
to Qumahlin
said by Qumahlin:You guarantee most won't, yet most users aren't experiencing this issue and in the case of the router that started the thread on DD-WRT forums that router WORKS FINE until DD-WRT is installed on it....so once again we are back to why is it the manufacturer was able to handle this scenario, yet DD-WRT is not. Users may not know they are experiencing the issue. I was for years and always just assumed the speeds I was getting over WiFi was the maximum I could get. They weren't terrible around 10 to 20 mbps, but once I implemented the "fix" they shot up to 50+ mbps. |
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incanibus
Anon
2014-Jan-24 8:01 pm
Just wanted to say this worked on my netgear wndr3400v2. I'll be honest, what you all are talking about is way beyond my knowledge in networking. I couldn't get the first script to work so i gave the second edited script a shot. Download speed went from a max of ~15 to 45mbps instantly. Can't thank you enough, been trying to troubleshoot this thing for months. |
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Incanibus to Qumahlin
Anon
2014-Jan-24 8:48 pm
to Qumahlin
I can also confirm that the issue is not limited to ddwrt. I had similarly slow speeds on the stock netgear firmware. |
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GTFan
join:2004-12-03
Austell, GA
1 edit |
to incanibus
said by incanibus :Just wanted to say this worked on my netgear wndr3400v2. I'll be honest, what you all are talking about is way beyond my knowledge in networking. I couldn't get the first script to work so i gave the second edited script a shot. Download speed went from a max of ~15 to 45mbps instantly. Can't thank you enough, been trying to troubleshoot this thing for months. Yeah I wish the OP would update his first post, the 'long' dash that he has in the iptables command for the set-dcsp option will not work with copy/paste (it has to be a double-dash, '--') which is why I posted the update. I'm also curious why a Comcast net eng posted a while back that they were looking into this and then disappeared without an update. My guess is that they're doing this on purpose to prioritize their voice traffic but it really should be stripped before it gets to the consumer's router. |
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to Morac
said by Morac:said by Qumahlin:You guarantee most won't, yet most users aren't experiencing this issue and in the case of the router that started the thread on DD-WRT forums that router WORKS FINE until DD-WRT is installed on it....so once again we are back to why is it the manufacturer was able to handle this scenario, yet DD-WRT is not. Users may not know they are experiencing the issue. I was for years and always just assumed the speeds I was getting over WiFi was the maximum I could get. They weren't terrible around 10 to 20 mbps, but once I implemented the "fix" they shot up to 50+ mbps. I was getting the same, but I am not one who just assumes WiFi is slow(I tested local speeds first), I track down bottlenecks and make sure issues like this are isolated. said by Incanibus :I can also confirm that the issue is not limited to ddwrt. I had similarly slow speeds on the stock netgear firmware. This is good to know it affects many brands. said by GTFan:said by incanibus :Just wanted to say this worked on my netgear wndr3400v2. I'll be honest, what you all are talking about is way beyond my knowledge in networking. I couldn't get the first script to work so i gave the second edited script a shot. Download speed went from a max of ~15 to 45mbps instantly. Can't thank you enough, been trying to troubleshoot this thing for months. Yeah I wish the OP would update his first post, the 'long' dash that he has in the iptables command for the set-dcsp option will not work with copy/paste (it has to be a double-dash, '--') which is why I posted the update. I'm also curious why a Comcast net eng posted a while back that they were looking into this and then disappeared without an update. My guess is that they're doing this on purpose to prioritize their voice traffic but it really should be stripped before it gets to the consumer's router. Yeah, Comcast seems to be ignoring this issue right now, Ill maybe call business support and see if they are any more helpful(I now have a business line through them which also has the same issue). I can't seem to edit the OP, ill see if I can get a mod to fix it(copy paste must have removed the extra dash somehow). I don't care about Comcast prioritizing their own traffic as much as them not stripping DSCP. Their prioritizing would not affect people all that much but leaking CS1 DSCP does. |
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MoracCat god
join:2001-08-30
Riverside, NJ |
Morac
Member
2014-Jan-27 12:33 pm
said by Morac:They weren't terrible around 10 to 20 mbps, but once I implemented the "fix" they shot up to 50+ mbps. Actually it wasn't just raw speeds, but speeds at a distance. Without the fix here, I could get speeds around 45 Mbps less than 15 feet from my router, but the speeds dropped to 10 Mbps or less at about 30 feet. After I implemented the fix, I can now get 57 Mbps virtually everywhere in my house. Many people might end up buying an extender when one is not needed. |
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to jhilliar
This problem is absolutely not limited to routers with custom firmware. I have a Linksys E2000 that has always had stock firmware, and for a long time (until I saw this thread) just assumed it couldn't handle more than 15-20 Mbps. Once I saw this thread, I checked Wireshark and observed the 0x08 DSCP value. I purchased a Ubiquiti ERL and configured it to set DSCP on all inbound packets to 0x00, and switched the E2000 to AP-only mode. All of a sudden I get the full 50Mbps over WiFi. I agree that this is something that "should" be handled by the router manufacturers, but no matter who "should" fix it, Comcast will be the ones dealing with users upset about slow WiFi speeds and switching to competitors. So Comcast is risking losing non-technical customers over this and has the ability to remedy it. |
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said by Kadomony:This problem is absolutely not limited to routers with custom firmware. I have a Linksys E2000 that has always had stock firmware, and for a long time (until I saw this thread) just assumed it couldn't handle more than 15-20 Mbps. Once I saw this thread, I checked Wireshark and observed the 0x08 DSCP value. I purchased a Ubiquiti ERL and configured it to set DSCP on all inbound packets to 0x00, and switched the E2000 to AP-only mode. All of a sudden I get the full 50Mbps over WiFi. I agree that this is something that "should" be handled by the router manufacturers, but no matter who "should" fix it, Comcast will be the ones dealing with users upset about slow WiFi speeds and switching to competitors. So Comcast is risking losing non-technical customers over this and has the ability to remedy it. Custom firmware such as tomato use the same WL driver that stock routers do so it is of no surprise that stock routers have the same issues. The difference is that with customer firmware you can use iptables to strip the 0x08 DSCP value. |
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to jhilliar
Can someone post step-by-step instructions on how to fix this for someone computer literate but not as advanced. |
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said by juniorafu:Can someone post step-by-step instructions on how to fix this for someone computer literate but not as advanced. This(» www.dd-wrt.com/wiki/inde ··· allation) may help. You can then just add the iptables script. |
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1 edit |
to jhilliar
I experienced this issue today it drove me nuts for 3 hours until I found this thread.
I was helping someone who switched from ATT DSL to Comcast Cable. They never had issues in the past, wired and wireless were always getting the same speeds.
Everything on the network was the same except the ISP.
After switching to Comcast speedtests showed 25(down)/10(up) for wired computers. The wifi clients where only getting ~.5(down)/10(up).
As soon as WMM Support was disabled, the wifi clients were getting the same speeds as the wired computer.
Router Model was a Linksys e1200 V1 running dd-wrt.v24-21676_NEWD-2_K2.6_mini-e1200v1.bin |
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Wondering if Comcast is going to do anything about this ever, seems everyone who was looking into it disappeared. |
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Dyskresiac
Anon
2014-Mar-28 1:38 am
THANK GOD this worked! Was getting around 25Mbps on my Cisco E2500 v1
Installed Tomato, ran these scripts, now I'm getting full 60Mbps that I'm paying for. Thank you! |
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 ·Carolina Mountai..
Synology RT2600ac
Linksys E2000
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to jhilliar
I'd like to know more on this, as I use an E2000 Router with stock firmware here (Latest, Last firmware).... Could the Step-by-Step instructions be posted separately for us less than advanced users? |
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Xfin70
join:2013-07-22
Covina, CA
1 edit |
to jhilliar
I guess Comcast is not going to address this? Maybe we need a class action suit against them to wake them up and reimburse those of us who had to implement costly network changes? I had to replace all my routers to get the speed I should've been getting all along. I spent many hours and a lot if $$$ trying to figure this out, and found this thread and it was fixed. |
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said by Xfin70:I guess Comcast is not going to address this? Maybe we need a class action suit against them to wake them up and reimburse those of us who had to implement costly network changes? I had to replace all my routers to get the speed I should've been getting all along. I spent many hours and a lot if $$$ trying to figure this out, and found this thread and it was fixed. Would be nice to at least get an official statement on the issue from Comcast. |
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Xfin70
join:2013-07-22
Covina, CA |
Xfin70
Member
2014-Mar-29 8:27 pm
True, any information would be nice. If they have a reason for it, cool. At least let everyone know so they can purchase a router that can be manipulated and have firmware modified so their speeds aren't slowed down. |
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said by Xfin70:True, any information would be nice. If they have a reason for it, cool. At least let everyone know so they can purchase a router that can be manipulated and have firmware modified so their speeds aren't slowed down. Yeah, they should post a notice when signing up for service that Comcast doesn't properly support N or newer wireless routers(N and newer have mandatory WMM) without DSCP stripping capability. |
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Sosebee6147 to Xfin70
Anon
2014-Mar-29 11:13 pm
to Xfin70
I feel like a real idiot, I have been dealing with slow speeds since I signed up over a year ago. I WANT SOMETHING DONE, I have spent hours upon hours entering reports for work that should have taken 1/4 the time. I even have the comcast router they lease you. Even went and bought a new laptop thinking mine were just old and bogged down. NOW i find this when I am getting the same speed with the new laptop. I know enough to be dangerous, but if anyone can tell me how to fix this problem I would greatly appreciate it. This has slowed down my data entry which has slowed down my income as well because I cant get the reports entered as quickly. I am able to work faster on my IPhone than my laptop. PLEASE HELP...Lets start a CLASS ACTION SUIT, I ask them the other day if I had a slow internet package and was told I had the best. I think NOT..Thanks for any help.. |
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Daemon
Premium Member
join:2003-06-29
Washington, DC |
to Xfin70
said by Xfin70:I guess Comcast is not going to address this? Maybe we need a class action suit against them to wake them up and reimburse those of us who had to implement costly network changes? I had to replace all my routers to get the speed I should've been getting all along. I spent many hours and a lot if $$$ trying to figure this out, and found this thread and it was fixed. Good luck suing them for what is essentially a bug in your router's firmware. Comcast does a lot to work around all kinds of CPE bugs, but they aren't legally required to do so. I agree that it's "Comcast's problem" because it's a customer problem, but it isn't "a problem with Comcast". It's a problem with routers paying attention to information they, per the RFC, should ignore. (Keep in mind that what Comcast "should do" and what you can suing them for doing/not doing are completely different things.) Also, those of you running DD-WRT: has the issue been reported to the firmware developers as a potential bug? |
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to jhilliar
If Comcast is trying to make sure their voice/ip-video packets get first dibs why don't they just raise those packet's priority instead of lowering the internet packet's priority to the point that the customer's routers drop them? |
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 your moderator at work
 hidden : Spam
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to Daemon
Re: [Speed] PSA: Slow WiFi on Comcast? May be Comcasts Faultsaid by Daemon:said by Xfin70:I guess Comcast is not going to address this? Maybe we need a class action suit against them to wake them up and reimburse those of us who had to implement costly network changes? I had to replace all my routers to get the speed I should've been getting all along. I spent many hours and a lot if $$$ trying to figure this out, and found this thread and it was fixed. Good luck suing them for what is essentially a bug in your router's firmware. Comcast does a lot to work around all kinds of CPE bugs, but they aren't legally required to do so. I agree that it's "Comcast's problem" because it's a customer problem, but it isn't "a problem with Comcast". It's a problem with routers paying attention to information they, per the RFC, should ignore. (Keep in mind that what Comcast "should do" and what you can suing them for doing/not doing are completely different things.) Also, those of you running DD-WRT: has the issue been reported to the firmware developers as a potential bug? Well, its complicated since Comcast is marking incorrect DSCP, while it would be ideal for consumer routers to strip DSCP as far as I know not a single one does that by default. said by madbavarian:If Comcast is trying to make sure their voice/ip-video packets get first dibs why don't they just raise those packet's priority instead of lowering the internet packet's priority to the point that the customer's routers drop them? That does not seem to be what they are using DSCP for...seems they are using it for something else, probably to distinguish internet traffic from their internal IP services. |
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tmarsh151
Anon
2014-Apr-1 9:53 pm
I have a Netgear WNDR4300 with the most recent stock firmware version and am experiencing this issue as well. I have logged a support ticket with Netgear in the hope that they may be able to address the problem. |
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Daemon
Premium Member
join:2003-06-29
Washington, DC |
to jhilliar
said by jhilliar:Well, its complicated since Comcast is marking incorrect DSCP, while it would be ideal for consumer routers to strip DSCP as far as I know not a single one does that by default. It depends on what you consider incorrect. Comcast is using that DSCP information "correctly" within their own network. Per RFC, home routers should ignore the DSCP values on cross-network traffic. There is no reason why a home router should prioritize traffic within its network using the priority Comcast, or any other external ISP, has set, ever. It's kind of like you following instructions UPS has placed on a package to help them route it to your house. It's also possible that comcast eMTAs do make use of the DSCP information in order to prioritize VOIP traffic, thus the DSCP information should be preserved to at least some CPE. The real issue here, I think, is why home gateways are using DSCP information in packets for LAN side routing, but forwarding packets across the WAN to LAN boundary with DSCP intact. For a home router to use WMM/QOS, it has to be able to set DSCP information, so why not have it clear the bits in the packet as it forwards them? Or, at the very least, ignore them? FWIW, I've used several Apple-branded home gateways as well as a NetGear gateway and have not experienced any of the symptoms described here. So not all home gateways are trusting the DCSP information unmodified. |
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said by Daemon:said by jhilliar:Well, its complicated since Comcast is marking incorrect DSCP, while it would be ideal for consumer routers to strip DSCP as far as I know not a single one does that by default. It depends on what you consider incorrect. Comcast is using that DSCP information "correctly" within their own network. Per RFC, home routers should ignore the DSCP values on cross-network traffic. There is no reason why a home router should prioritize traffic within its network using the priority Comcast, or any other external ISP, has set, ever. It's kind of like you following instructions UPS has placed on a package to help them route it to your house. It's also possible that comcast eMTAs do make use of the DSCP information in order to prioritize VOIP traffic, thus the DSCP information should be preserved to at least some CPE. The real issue here, I think, is why home gateways are using DSCP information in packets for LAN side routing, but forwarding packets across the WAN to LAN boundary with DSCP intact. For a home router to use WMM/QOS, it has to be able to set DSCP information, so why not have it clear the bits in the packet as it forwards them? Or, at the very least, ignore them? FWIW, I've used several Apple-branded home gateways as well as a NetGear gateway and have not experienced any of the symptoms described here. So not all home gateways are trusting the DCSP information unmodified. Actually, I don't think a router has to have the ability to set DSCP in order to read it. I know for WMM the wireless driver itself reads DSCP and not the main linux operating system(virtually all home routers are linux based). Without full iptables access manipulating DSCP on a home router is nearly impossible since most will not give a GUI option for it. There is a large CPU cost for performing packet manipulations vs simply forwarding packets(NAT) and DSCP modifications do take significant CPU. DSCP values I believe was designed to be set by the application itself ex. VOIP where it would be beneficial to cross network boundaries(although in practice it would seem that every ISP simply strips DSCP values). In general home routers are simple embedded linux computers with not a lot of CPU power, this is an issue solved far easier by Comcast. If Comcast want to keep this network configuration they really should publish that their downstream traffic has a non-standard DSCP marker and that the customer will need to find a way to strip those DSCP markers, maybe have a nice iptables guide to go along with it when signing up for services. Since I don't think that will go over all that well with customers they will probably stay more or less silent until they are able to strip DSCP on their end whenever they do network maintenance. |
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willmo
join:2013-06-03
Seattle, WA |
to Daemon
said by Daemon:For a home router to use WMM/QOS, it has to be able to set DSCP information, so why not have it clear the bits in the packet as it forwards them? Or, at the very least, ignore them? I doubt most home router manufacturers even think about the DSCP. They simply grab a bunch of open-source and proprietary software, including the Linux 802.11 stack that maps DSCP <---> WMM; hit it until it seems to work; and ship it. Even if some manufacturer realized that they should modify the DSCP, they might not be inclined to, for performance reasons as jhilliar said (and as I mentioned earlier in the thread). Many home routers nowadays use SoCs that include NAT hardware acceleration. I haven't read much about their capabilities, if they're even public, but I wouldn't be surprised if they couldn't change the DSCP. Even for those that use software NAT, there is a performance cost. |
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TAZ
join:2014-01-03
Tucson, AZ
1 recommendation |
TAZ
Member
2014-Apr-16 4:00 am
said by willmo:Even for those that use software NAT, there is a performance cost. Even this isn't an excuse for router manufacturers, it's just laziness. The performance cost of this iptables rule is basically all overhead - the additional rule to be traversed, the function call to the DSCP module's handler, cache space for this, etc. If someone just added an "iph->tos = 0;" somewhere in the stack (in iptables is probably the most convenient point), the performance cost would be near zero. It's a hack, but at least it eliminates this excuse. |
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