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Can Any Router Guarantee Bandwidth For VoIP?
cartman94501 writes "My wife and I use Vonage for Voice over IP at home, mainly for work-related phone calls so we don't have to give out our home number to clients and colleagues. Most of the time it works fine, but when I'm using BitTorrent or other high-bandwidth applications (purely for legal and non-copyright-violating purposes, of course), the call quality gets choppy. I have used my Linksys (not a WRT54G, so 'upgrading' it to Linux probably won't work) router's QoS feature to assign high priority to the MAC address of the Vonage box, low priority to the BitTorrent box, and medium quality to everything else, which helps a little, but not enough.
Is there a router out there that would allow me to reserve, say, 75-90kbps of bandwidth off the top for VoIP and never, ever allow any application to use that, regardless of whether there's a VoIP call going on at the moment or not?" (More below)
cartman 94501 continues: "That would solve my problem, but I fear I'd have to build a Linux box and learn all sorts of esoteric commands to really make that work. Are you aware of a commercially-available router that would allow me to accomplish this goal with some sort of ease? While I'm not prepared to pay four figures, I'm certainly not naïve enough to expect such a device to be available in the $50-100 range of your garden-variety wireless router. Wireless would be ideal, but if I could patch it in between my existing wireless router and the cable modem, and turn off QoS entirely on the existing router, that would work, too."
Most gaming routers allow for this kind of functionality. In fact the first search result on google for 'gaming router' brought me to a product from dlink that provided exactly that.
Perhaps try picking up a WRT54GL and installing Tomato on it.
and a WRT54GL cost me $100 (NZD) so i'm assuming it's $60-70 USD and with DD-WRT will do what you want and more.
www.ipcop.org
www.endian.com
www.smoothwall.org
Full-featured firewalls, will run on old crappy hardware you got laying around the garage. All you need is two NICs. Viola. QoS no problemo.
Just disrupt the deflector shield with a tachyon burst.
I use a Dlink appliance that works well, requires zero configuration and is placed in between the router and the modem - Voip Internet Accelerator Intelligent Packet Priority Engine Manufacturer Part Number: DI-102 Never had a single problem over more than a year of use.
If you're running a business, your first worry should be about servicing your customers not using Bittorent. Get another DSL/Cable/Wifi connection for your business and run your VOIP over that.
If you only need the limited bandwidth that you are looking for you'd be fine with the lowest speed (read cheapest) connection any ISP offered.
Interesting exploration of the issues here: http://www.formortals.com/Home/tabid/36/EntryID/57/Default.aspx
QOS should work if you set it up properly.
On my WRT-54GL with Tomato (others might work, Tomato is the easiest of ddwrt, openwrt in my experience), the QOS settings can be limited in just the way you want, with everything except the highest only being allowed only 75% of your upload, or whatever you want.
Downstream is a bit harder to restrict, since the queue is on the Telcom side of things, but you could do some QOS in your router there as well.
If I have nothing to hide, don't search me
I have heard that most ISPs put VOIP packets on super-low priority anyway, so even your setup at home won't affect it a whole lot. I may have heard wrong, though.
Suppose your upload speed is 150Kbps. A single bittorrent packet is 15,000 bits, so it takes a tenth of a second. If there is a bittorrent packet in the router when the VOIP packet arrives, the VOIP packet still has to wait for the bittorrent packet to finish, which means waiting up to a tenth of a second. Even though the VOIP packet always gets priority over other waiting packets, it will often arrive when the router is otherwise engaged, and therefore likely to endure a tenth of a second delay, which is probably noticable. I suppose reducing the MTU might be a help.
I have the Sunrocket "widget" (Linksys voip adapter) plugged directly into my dsl modem, and my router plugged into the widget. The widget is supposed to give its own data priority, but I've never seen any evidence of that.
But if all you care about is keeping BT from using the last XX amount of bandwidth, just dial your max upload and download speeds down in the BT client.
Between the modem and the router. Hook the phone into the adapter as usual.
The adapter is what guarantees bandwidth for your phone.
Purchase a WRT54GL (not any other WRT54G, unless you know what you're doing) and install the Tomato firmware on it. Not DD-WRT, not OpenWRT or any of the others. Tomato has better QoS and Traffic shaping functionality than most commercial firewalls I run.
The problem is related to the amount of traffic coming to you from the internet. No amount of QoS applied to your router will be able to shape the traffic that is piling up against the provider's side of the link to your house. That leaves you with 2 options:
1. If your BitTorrent client supports it, set the maximum download rate to less than what your internet connection speed is. I won't guarantee this will completely solve the issue, but it should help.
2. Don't download big files while you are using your VoIP phone.
This has worked for me, no regrets.
Once you're past the router you'll also have the problem that your ISP may not be honoring the QoS tagging of the VoIP traffic or otherwise identifying it and giving it priority. (In fact they may chose to identify it and give it LOWER priority if it's not theirs.)
So fixing your router may only be half the solution: It may throttle back your BitTorrent traffic to keep from stepping on the VoIP packets on the way to your ISP's first box, only to have it stomped by somebody ELSE's BitTorrent (or whatever) traffic on the next hop.
This, by the way, illustrates both halves of why "network neutrality" can't be just "treat all packets the same". You have to give the VoIP packets priority in scheduling over the BitTorrent packets to get them to work well (which doesn't do anything but slightly slow BitTorrent). But the tools to do that also give an ISP the ability to give the VoIP packets for their high-dollar service priority over BitTorrent while letting their competitors' VoIP packets fight it out, or even be handicapped further. Now try writing legislation to mandate the first while forbidding the second.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
I know you're looking into the router, but another option is to impose a limit in your BitTorrent client. I know UTorrent has functionality for restricting upstream and downstream speeds. Perhaps the client you are using has the same capabilities. Or perhaps I'm just made a worthless point, let the mods decide!
-
Soon to be modded -5 retarded, Bob
Short answer, not really.
Longer answer, any circuit where you don't have a predictable amount of bandwidth will be hell to build any QoS with. Pretty well any home user connection will be in this class. Most of the cheap consumer devices that claim to do this are relying on tricks that won't work in a heap of cases or worse are snake oil.
No device is going to be able to do a good job without a heap of background information on what your connection is an how it behaves, things like when the buffers for outbound traffic on the other end of your DSL line kick in and behave etc.
If you want to learn a whole bunch of esoteric commands and a bit about networking you should be just fine building something to do it with a Linux box =)
Alternatively you might get a 95% successful solution if you buy a consumer device and shape the internet facing interface down to a speed that you hope your circuit will never drop below.
I am a lawyer and this constitutes legal advice and I shall indemnify you against any losses arising from taking it.
What such routers are doing is only "outbound packet DSCP marking". In English this means that once you configure such routers, only the packets that you send out to the Internet will be marked to exibit the behaviour you desire; however... and this is a BIG however, the fact of the matter is that:
1) Whilst you have marked some packets high, medium and low pririty, your ISP and every other Telco/ISP on the Internet may completely ignore those markings (preferences) of yours.
2) In fact, some of them may "remark" all your packets back to the same level, effectively disabling QoS.
3) Most routers mark packets outbound, and little emphasis is placed on inbound marking. This is because by the time the packet gets to you, unless YOUR router is saturated the packet will get through with low latency.
In order for QoS to work effectively the following things must be in place:
1) Every single network device along your network path must support QoS. This is NOT the case with 99% of the Internet. Not because the routers aren't capable of such, but rather because the ISPs disable this function for customer marked traffic.
2) Even if every network device from your home PC, router, to your ISP, the 6 telcos in the middle of the Internet cloud and your destination website in China supported QoS, chances are they would not all agree on what each marking would mean, and therfore they would interpret them incorrectly (from your perspective).
3) QoS only comes into effect when a network point is saturated, during all other times of bandwidth being available, QoS has next to no effect.
Further,
VoIP is UDP based, and is highly sensitive to latency. The Internet is a place where latency is highly unpredictable and the more network hops (the further geographically) your packets have to travel, the higher the end to end latency will be; as such, VoIP is likely to remain a low quality voice transport for a while. Contrastly, your analogue telephone line, when you make a call from US to China, actually reserves an entire set of *dedicated* DS1 (64Kbits/sec) analogue pipes from one end to the other. In other words, there is zero sharing; hence the guarantee and high quality.
Perhaps one day, when all the major Telcos and ISPs have more pipe than they know what to do with, long distance VoIP will come close in quality to analogue phones... until then it's a complete crap shoot. You might get amazing quality to some locations on some days, at certain times 99/100 times, and to other locations 80/100 times the VoIP call is utterly useless.
In resume, you can tweak your home router all you want. It might help slightly since your router would become a saturated network point due to you using bitorrent simultaneously; however, the other 8+ hops to get to "China" are completely out of your control.
My recommendation is that if you have a say 1Mbit Up/Down pipe for broadband internet; that before you make your VoIP call, that you throttle your bittorent software (in the software itself) to use only 850Kbits up/down. VoIP protocols can suck up anywhere between 8Kbit/sec (highly compressed) to 110 Kbits/sec (uncompressed). So by leaving 150Kbits for VoIP, there's a good chance the VoIP and torrents can co-exist peacefully.
Cheers, ADeptus
No trees were killed in the making of this post; however, many trillions of electrons were horribly inconvenienced.
Why not just get your VoIP through Comcast? They'll have no problems throttling your bandwidth for you for no extra charge.
There are a few ISPs that have blocked VOIP, mostly (ex-) monopoly telcos in various countries that want to charge you by the minute for voice. But most ISPs, and especially non-telco ISPs, don't care, because voice doesn't use that much bandwidth (especially if you're using compression.) BitTorrent's a different game - it's using something in excess of 1/3 of the bandwidth on the internet, so there are reasons for some ISPs to care about it other than just greed and spite :-)
The real problem is that ISPs don't put VOIP on high priority, and applications like BitTorrent, ftp, and to some extent http want to suck down all the bandwidth they can get and fill up any network queues they can to keep the data flowing. ISP backbones are fat enough that it doesn't matter that they don't prioritize VOIP, but the link from their last switch or router to your house is a finite size, and BitTorrent can not only crowd out the downstream link, but can queue up enough packets that your VOIP traffic needs to wait a while for its packets to get through, and the gaps kill your audio quality.
Also, the most critical thing for your router to control is prioritizing VOIP packets on the upstream, but apparently that wasn't enough to keep the article poster's calls working well.
don't know if you were serious or trolling anyway...
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
I also use the Tomato firmware on a WRT54G, and I have exactly the kind of setup the OP describes. I don't even remember what kind of QoS came with the default firmware, but I never had any kind of luck with it, nor with DD-WRT. Tomato has been great so far.
Tomato actually offers fairly sophisticated QoS rules. You can set priorities by MAC address, IP address, port, etc. You can even set bandwidth caps for specific protocols/ports; so, for example, you can set the first 512KB of data transferred over port 80 to "Highest" priority, while anything after that drops back down to "Lowest" -- the effect being that regular ol' Web surfing gets a little kick in the pants, but extended transfers are given less priority. The latest release even added the ability to prioritize small packets (ACK, SYN, etc.)
What's more, Tomato also offers really neat graphing of your traffic. You can actually see, in near real time, what percentage of your outbound traffic falls under which priority category, with a nice pie graph. This is especially helpful when you want to double check that your rules are actually working (and you didn't make a typo when you were entering in a Mac address, for example).
One thing to remember when you're setting up QoS on a router like this, though, is that you need to reserve a certain amount of upstream bandwidth just to manage to QoS overhead. So, say you have 384KB/sec upstream bandwidth. You'll probably want to tell the router to reserve 40KB/sec or so for QoS. YES, that means your maximum upstream bandwidth will in effect be lower than what your provider advertised; call it the cost of doing business with QoS.
I have no empirical measurements to offer. All I know is that with the original, official WRT54G firmware and also DD-WRT I saw virtually no difference whatsoever when QoS was enabled. My outbound voice quality on my VoIP line was very choppy, particularly (but not limited to) when I was doing BitTorrent. With Tomato, on the other hand, there seems to be a marked improvement. I can actually hear the difference when I check and uncheck the "enable QoS" checkbox.
Breakfast served all day!
I use a reasonably cheap PC setup for my boarder router (used to be just a 486) and have flawless Vonage VoIP service.
The thing you are doing wrong is that you are not _THROTTLING_ the link from your router to your cable modem.
In point of fact, and sadly, there is virtually no buffer for outgoing data on a cable modem. If you are configured for 768kbps upstream then sending data any faster than that will lead to all sorts of misery.
So in a properly configured firewall you want to throttle your _outgoing_ data to about 99% of your rated upstream bandwidth and _then_ use packet shaping to make sure that the right kind of packets get to "go first" in the QOS stack.
This turns your router into the buffer that your boundary modem lacks and will both make your VoIP flawless _AND_ _VASTLY_ improve your TCP/IP (web etc) throughput.
I have six ranks in my QOS gateway:
1) TCP ACKs (actually tcp packets less than 80 chars in length)
2) SSH (for emergencies)
3) VoIP (udp from my vonage device)
4) special occasions (none of your business 8-)
5) Games (udp in general)
6) Everything else.
Doing both of these things together will speed up everything in your house (including bittorrent) and leave you with outstanding voice quality even when gaming and running bittorrent while watching video on demand.
If found the basic rules files searching aroud the net, and then tweaked them with dynamic math and weightings.
Flawless.
Innocent people shouldn't be forced to pay for inferior software development.
--"Code Complete" Microsoft Press
I work as a techie for a company that makes some of those business-level priced routers.
Obviously, you don't have any control of the prioritization of the packets after they've been sent upstream to your ISP; if ISPs were let you do that, it would allow everyone to mark all of their traffic as high priority voice packets, and all prioritization would go out the window. The best you can do is to make sure your outgoing voice packets are prioritized over other outgoing traffic.
It is possible to influence the speed of incoming packets using TCP windowing. When devices establish a TCP connection over the net, they gradually increase the number of packets they send before waiting for a response from the receiver. This is the TCP window size. As long as there are no dropped packets, you normally want the devices at each end to use a large window size so more data is transmitted before the sender stops to wait for an acknowledgment. Some QoS-geared routers
(like the ones made by the company I work for) can be made to voluntarily limit the TCP window size of incoming data, so the device at the far end will pause more frequently to wait for acknowledgment. This has the effect of slowing incoming TCP traffic. Since voice packets are transmitted as UDP, this can help make more bandwidth available for them. Bittorrent traffic is transmitted TCP, so this kind of traffic limiting may help in this situation.
KTHXBYE
Actually, yes it should, as long as you also set your bit torrent to use a maximum of download bandwidth, and report as choked to the "supplier".
Most BitTorrent clients allow you to control the upload and download bandwidth consumed by the torrent(s). Limit the total of your torrents to about 1/3 of your measured (as opposed to advertised) available bandwidth in each direction. I had the same issue with VPN connections to remote desktops and found that this was enough to restore performance.
If the torrents are saturating your bandwidth, there isn't a lot a router can do with QoS to avoid choppiness. And if you keep your torrents to less than half your bandwidth QoS isn't necessary. QoS could possibly help you run at the maximum possible torrent speed without losing VOIP clarity, but you'd still have to fiddle around with the bandwidth limits on the Torrents.
We are the 198 proof..
What most people don't understand about TCP (and therefore bittorrent etc) and Cable Modems could fill a book.
The thing most people don't understand about cable modem is that it has virtually no buffer for outbound traffic (e.g. the traffic you do control) so subsequently it is almost a given that you will overrun the transmit buffer on your cable modem doing the simplest of things. This in turn will destroy all your throughput because...
The thing most people don't understand about TCP is that it accelerates linearly and falls back exponentially. So whenever you drop an acknowledgment frame (outgoing) then your incoming data session tends to stumble to a near halt. (that is each successful frame you send increases the transmit window by one frame, but each failure cuts the transmit window in half, and most failures cause at least two drops.)
This can be seen when you use a "near by" internet speed test (a la speakeasy) and you see the speedometer surge and fall like someone revving their engine. But each "fall" is actually a bunch of trash hitting your system and then getting discarded as the stream colapses back on itself.
Now for a cable modem provider, they have no interest in throttling data coming to you to your downstream cap. That would be expensive and would just clog up the memory in their routers. your downstream limit is really implemented as an aggregate of your upstream capabilities and how their time division multiplexer is configured to cascade into statistical multiplexing. (See Comcast's "speed boost" as an example of free-wheeling and only cutting back if it must.)
So anyway, I have posted my firewall and traffic shaper scripts to my slashdot journal. They are drop-in ready for Ubuntu and Slackware, minimal editing may be needed for RedHat or others.
Try them out. Be particular to tune the top of the shaper file for the upstream speed to match your _advertised_ cable modem rate (INTERFACE_SPEED=768 in the file) and then you can fine tune the numerator part of the fraction in CEILING=... (98 worked best for me).
I get my full 8M down PLUS whatever speed boost is doing (24M down often) and my VoIP works great, even during peak usage etc, while people are gaming and web surfing in the house (my house is a high usage environment with multiple housemates skyping and gaming etc).
On top of that, the script is actually _BENEFICIAL_ to my ISP. By shaping my outgoing traffic I waste virtually zero bandwidth on retransmits so I am a great net citizen.
(If you set your firefox to enable pipelining and set max pipeline requests to a value like eighty (yes 80) you will find that you are a most efficent and therefore quite spunky web citizen.)
Share and Enjoy...
Innocent people shouldn't be forced to pay for inferior software development.
--"Code Complete" Microsoft Press
The built in QoS on all the open linux firmwares only does outbound QoS. You can use iptables on the linux firmware to do prioritization. Slashdot's filter won't let me post the script because of "too many junk characters" so sorry I can't post it. I didn't make the whole script up myself. There is a program called WRT54 Script Generator v1.02. What I've done is prioritize nntp based on ports and gave it 2-5000Kbps and TCP on port 80 and port 443 to something like 90% minimum of my max connection speed. The script uses the mangle option of iptables to effectively prioritize DOWNSTREAM http over nntp.
This was a huge find for me because an nntp download using 8 connections would kill my connection and trying to download a new podcast for example would take forever. Now, when something on http starts downloading, nntp goes to almost zero, and I really mean zero. It effectively gets killed until the http is finished. All this is running on a WRT54GL with dd-wrt but you should be able to use any of the other firmwares out there. You could easily do this same thing for VOIP. Just tell the script generator that you want your VOIP port to get a minimum of 500Kbps or whatever and it can get a minimum of that speed if it really needs it all.
What most people don't understand about TCP (and therefore bittorrent etc) and Cable Modems could fill a book.
:-)
Hence the reason one can find books on these subjects.
Please stand clear of the doors, por favor mantenganse alejado de las puertas
I have got a fanless 1GHz Via C7 based pfSense box that has really nice QoS support for VoIP. Not to be trifled with..
I chose a VIA chip because they have hardware crypto acceleration for AES, taking the CPU bottleneck out of the way so I can VPN in from a Cafe or whatever. pfSense also has a newer FreeBSD kernel to support the hardware crypto accelerator.
I can even run ntop on it!
Here's the hardware:
http://www.logicsupply.com/products/perimeter_f
What about http://m0n0.ch/wall/
I use monowall and it works well with the following caveats:
1. It takes a bit of knowledge to learn to setup the qos, but this is true of any effective qos router.
2. It takes a bit of playing to get the pipe size right. Set it too high and it's ineffective. Set it too low and you're not utilising your bandwidth.
3. Your internet connection speed should be fairly consistent, otherwise you will be tweaking #2 all the way to an early grave. ADSL and cable are consistent in my experience, wISPs are not.
4. Your ISP can't be throttling you, as was mentioned by some others in this discussion, for that would effectively bring you back to the problem of #2 & #3.
I've used a debian gnu/linux install on old PII hardware as a router and I actually found the QoS to be unequalled. Once you learn the syntax of iptables (and a dozen other sysadmin skills) it works pretty much perfectly to preserve voip quality. For somebody that doesn't mind getting his hands dirty I recommend a linux router/shaper as your best solution
But, as the OP mentioned, linux is a bit dreadful to set up as a router for the uninitiated. (I haven't tried IPcop or any of the dedicated solutions so I can't speak for those.) For somebody that likes a nice shiny push-button interface, you can't beat m0n0wall, and like I said, with a bit of playing around it too can be very effective at preserving voip quality.
And to those who recommend limiting your torrents to 15% of your max bandwidth: your heart's just not in it. I want my torrents now. I don't want to have to run turn down my torrents every time the phone rings, and I sure as heck won't remember to turn them up again when the call's done. It's a beautiful thing to watch a torrent upload at a steady 100% of your uplink speed, get on the phone, and see your torrent continue at 100% minus 86 kbps while enjoying a phone call with flawless audio, then see the torrent fill up the gap as soon as you hang up. Geek's paradise.
db
I am literally 3000 tokens away from the chaotic crossbow --Stephen
Tomato is really a great firmware, I think it is the answer to the initial post's problem. It really has a great interface and is easy to configure, DDWRT was nothing but headaches for me, and the QOS (When I used it a year ago) was absolutely broken.
here is a guide on configuring QOS, http://www.decimation.com/markw/2007/10/03/tomato-qos-setup/
Also it has great graphs such as realtime usage (tx and rx) reports http://en.wikibooks.org/wiki/Image:Tomato_Firmware_-_Bandwidth_Real_Time.PNG
And I can see a graph of exactly what percent of my traffic falls into which QOS classifications. http://www.polarcloud.com.nyud.net:8080/img/ssqosg108.png
I'm able to quickly check if anyone has been abusing the wireless, and see what percentage of my traffic is bittorrent, nntp, gaming, etc, If some device on the network suddenly started flooding traffic over port 25, I would know about it, all in a nice and easy color coded graph, check it out, I bet you will like what you find.
Web Developers: Celebrate to our roots! Animated Gifs and Tiled Backgrounds, dont let our history die!
The OP doesn't say but probably doesn't have a cable modem, he more likely has ADSL from the phone company.
I have fought those problems with VOIP and a poor DSL line. With a WRT54G and that optional firmware, and it was an abject failure. We couldn't solve the ADSL line problems at our end.
The solution is probably going to be calling his provider and demanding they give him the speed he is paying for, and if he's not paying for enough speed he may have to pay for more line speed.
The trouble with DSL is it is not guaranteed bandwidth. It can completely stop working for more than enough time to screw up VOIP and there is likely nothing he can do about it.
Cable modem service is typically enough faster than ADSL from the phone company he is much less likely to have these sort of problems, unless maybe his provider has installed Sandvine traffic management equipment and that is screwing him up detecting his P2P usage and throttling his circuit. I don't know if Sandvine equipment throttles the whole circuit or not. Does it? Does anyone know?
The funny thing is you would never have these problems on an ISDN circuit, which though slow by todays bursty ADSL standards is guaranteed bandwidth, just like that corporate OC-48 you have at work. You get two FM radio quality voice channels on ISDN and it does work, guaranteed. If not they *have* to fix it.
Whereas on ADSL they just say "sorry bub". Then they maybe say "If you got your VOIP from us I bet it would work". But only because in that case they would *have* to fix it. Evil telcos, to be sure.
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Priotizing bandwith with the Linux kernel's de-facto standard shaper HTB is not the correct approach if you care about latency. Nevertheless 95% of the internet's advise points exactly into that direction. What most people don't know, Linux already includes a shaper being able to make realtime scheduling guarantees: HSFC. It is a little bit more complicated to setup, but my box is able to give me 15 ms VoIP delays in parallel on a congested line (2000+ bittorrent peers).