Hello community!


I'm curious about bandwidth split at a DSL router.

I have a DSL router and have two PCs connected.

Of course - on both is BOINC ;-), if both PCs DL WUs simultaneously, the DSL bandwidth will be split 1/2 - 1/2 ? Or PC A or B is preferred?

If both PCs (A+B) DL WUs and at one PC (B) I DL additional something (or I surf the web) simultaneously, how it's then, A 1/3 - B 2/3 ? Or one PC is preferred?


Thanks!

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Hello community!


I'm curious about bandwidth split at a DSL router.

I have a DSL router and have two PCs connected.

Of course - on both is BOINC ;-), if both PCs DL WUs simultaneously, the DSL bandwidth will be split 1/2 - 1/2 ? Or PC A or B is preferred?

If both PCs (A+B) DL WUs and at one PC (B) I DL additional something (or I surf the web) simultaneously, how it's then, A 1/3 - B 2/3 ? Or one PC is preferred?


Thanks!

It isn't simple. Obviously if the source site is slow, the split is driven by that. And include the entire path between the source and you in that. If one of your computers is a tad slower than the other, that will change the split. If one of the paths is dropping packets, that changes the split. There are so many things that can be different, you can't ever have them all the same.

If it is the perfect case you should get something very close to a 50/50 split.

As to the case where one computer is trying to D/L two things at once, it can get more than 50% of the DSL. Or it could get less. If it can't keep up then obviously it gets less. If it can go faster then it may get more than half. But the outside world will be the controlling factor.

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Most common routers have switches in them to control traffic. So in an ideal world not counting over head or variances in a machine you would see a 50/50 split. But like Sutaru has said it doesn't all way work that way due to variances. If you are judging how well it's doing it's job based off of your download speed inside Boinc don't. They are very constant or predictable at the best of times.

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Traveling through space at ~67,000mph!

If you wanna control it, use QOS (Quality of Service). But still depends on the reaction time (speed) of the host your trying to communicate.

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Are you talking average bandwidth, in which case it will be very close to 50/50.
But if you are talking instantaneous then it will be dominated by the PC doing the communication. Generally the first one to shout gets the attention, then the router does some prioritisation magic to make sure the second one gets a reasonable chance with the objective of near equal over time.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Thanks to all!


I have an AVM FRITZ!Box, very popular in Germany, I think the most used brand/DSL Router here.
I looked in the menu of the DSL Router and found no possibility for to limit (manage/split) the DSL bandwidth for the PCs. For example over the LAN port #1 this speed and.., or some way.

The problem is, that I have only DSL light (384/64 kbit/s - or 48/8 KB/s). More isn't possible here where I live.

It's look like, that if I haven't set a limit in the computation prefs, that PC A (on LAN port #1) have little bit more priority (more DSL bandwidth) than PC B on LAN port #2 - and disturb PC B. I worry he get more backlogged DLs because of this.

If I set for both PCs a 24/4 KB/s limit, both PCs DL in the same speed WUs.


For to reach a 50/50, is there a tool (for free! ;-) which I could have on the PC, which control/limit the DSL bandwidth?
(E.g. if I DL on PC A something, that not the whole DSL bandwidth will be used - and disturb PC B. I guess the OS (WinXP Home) is smart enough for to split the DSL bandwidth on one PC.)

But, I use the remote function in BOINC, for to manage PC B over PC A. The 100 MBit/s LAN shouldn't be reduced. Or how much LAN bandwidth is needed for well remote control?
Or DSL and LAN bandwidth are two different pair of shoes?

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I can only give u the advice Sutaru, not to do any traffic-shaping; in your situation, it can only getting worse with the overall network bandwith/speed.

But why not think about a surf-stick, if u need sometimes more capacity? Ok, not realy practical and bit to expensive, but worth to mention this "workaround" :-)

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- Performance is not a simple linear function of the number of CPUs you throw at the problem. -

But I need to split the DSL bandwidth (maybe only during computation prefs), for to get ~ 50/50.
If not, PC B get not enough bandwidth.

The sad is that the currently available surf sticks (AFAIK) are like this, that if you have 2 or 3 GB or little bit more traffic in month your speed will be reduced to 56k modem. And because of SETI@home this is reached very fast. ;-)

Or you know maybe an ISP which have no limit?

The same also with SAT DSL (IIRC, only DSL 2000), you have a user friendly policy, which say that's not allowed to use 24/7 the whole bandwidth/connection. If yes, you get the termination or also down to 56k or someting.

It's not easy to live in a village, DSL topic related. ;-) :-(

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Sutaru,

What is the problem? The router will do a better job proportioning the connection than you can and it does it on a milli-second level. If you are having VIOP issues QOS can help. QOS gives priority to real time streams.

The issue may come down to you needing more bandwidth. If a faster connection isn't possible, is a second connection possible?

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If you are faced with having a 56k up link then you can expect BOINC and so SETI to be painfully slow. I've tried to run BOINC/SETI on a single PC at that sort of rate and can say it is painful, with frequent timeouts causing loss of the link, so may retries.
The best I can think of is some form of manual timeshare, so only one computer is trying to do its communication at a given time. This will have two advantages, first you won't have PC to router retires, and second the communicating PC will have all the available bandwidth. One way would be to set times at which each PC can communicate in the Advanced/Preferences/Network tab to be different, for example PC one as 00:01 to 12:00 and PC two as 21:01 to 24:00. Now the PCs will not be fighting over a very small amount of band width, and you will have a reasonable chance of getting you results delivered and new receive new WU.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Thanks again.

Sutaru,

What is the problem? The router will do a better job proportioning the connection than you can and it does it on a milli-second level. If you are having VIOP issues QOS can help. QOS gives priority to real time streams.

The issue may come down to you needing more bandwidth. If a faster connection isn't possible, is a second connection possible?

I have the feeling that the PC which is on the Router LAN port 2 get little bit less bandwidth if both PCs DL WUs. If I look in BOINC's transfers overview.
I worry that if both PCs want to DL WUs simultaneously, that they interfere with each other and because of this the DLs go in backlog.
Or this is not possible, because the DSL Router is so smart to share the available DSL bandwidth 50/50?

What will happen if I DL manually something on PC A simultaneously to the WU DL? PC B's connection will not disturbed?
The OS will split the two DLs on PC A and the DSL Router will split the bandwidth between the both PCs, so it will be 2/3 PC A and 1/3 PC B?

No, no 2nd connection possible.

(If I limit the speed to 24/4 KB/s per PC (BOINC prefs), the WU DL speed is split 50/50.)

If you are faced with having a 56k up link then you can expect BOINC and so SETI to be painfully slow. I've tried to run BOINC/SETI on a single PC at that sort of rate and can say it is painful, with frequent timeouts causing loss of the link, so may retries.
The best I can think of is some form of manual timeshare, so only one computer is trying to do its communication at a given time. This will have two advantages, first you won't have PC to router retires, and second the communicating PC will have all the available bandwidth. One way would be to set times at which each PC can communicate in the Advanced/Preferences/Network tab to be different, for example PC one as 00:01 to 12:00 and PC two as 21:01 to 24:00. Now the PCs will not be fighting over a very small amount of band width, and you will have a reasonable chance of getting you results delivered and new receive new WU.

No, I have 384/64 kbit/s.

Thanks for the hint, but I guess this would work only if the SETI@home server would be available 24/7.

PC A need 190+ WUs/day PC B 700+ WUs/day.
If I would cut down the time they could reach SETI@home, I guess they will not have enough time for to UL the results, request enough WUs and DL them then.

I wouldn't have all the problems if my house would have a faster connection to the www.
The max is 384/64 kbit/s which come down and up, although I buy DSL 2000 at my ISP (which is the cheapest offer/ISP).
The 'internet point' in our village can't manage/support more speed.

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What is your real connection speed, not the theoretical speed?

Next we do a rough calculation to see how many bits of data are to be transmitted every day.
Assume that for every byte of data to be moved you need ten bits to be moved (data speeds are normally quoted in bits per second).
A single SETI WU is about 370kBytes, so that's 3,7000kbits of "useful" data.
Now add 50% for the overheads, these are the packet wrappers and addressing data that gets the data from the SETI server to your PC and makes sure its all there.
We are now at 5,500kbits of data for a single WU that arrives safely at your PC.
I would assume there are other packets that get sent as well, such as confirmation of dispatch, system messages, heart beats, all of which add to the data on your very small pipe. This could add another 10-20%, so we are now at about 6,000kbits of data per WU, which on a good day is the best part of 20seconds if we allow for the "latency" inherent in the systems (the time it takes for your requests, confirmations and so on to be sent and processed at each end).

So where does this leave you?
Well you are looking at about 900 WU per day, so that's 900 times 6,000kbits of data to be delivered. which is about 5,400kbits of data, or 900 time 20 seconds of transfer time, or about 5 hours of your best communications time - that's a long time :-(

You certainly need a better link, or you will have to be be both very lucky and very patient.

I've deliberately ignored the results you will be sending back and any drop-outs and data retries, but that makes the problem even worse :-((

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

http://en.wikipedia.org/wiki/Packet_switching
The router is smart enough to divide the channel in the most efficient manner. That may not be exactly 50/50, but it will be darn close if the requests come to it 50/50.

There is also the issue of packet collisions on the LAN side in the ethernet world. It is very possible that the random back off timing isn't random. That could cause one machine to always be first after a collision, hence favoring that machine. That back off timing is a function of the NIC. There is also the strong possibility one machine is just a bit faster than the other, thus the faster one gets two packets sent while the other only gets one out, or maybe 10 to 9. In any case none of this is controlled by the router.

If as Rob suggests you have maxed out your upload link, then your options are limited. Buy a second DSL line, or get a faster one (business class?) or change your crunch parameters. Perhaps put in a project that has longer run times and/or smaller work unit data to transfer. Or you could put a throttle on BOINC so it only uses a % of the available horse power. There is a preference for that, normally used to keep laptops cooler. If you can't do any of these then you just have to accept that from time to time one of machines will go idle. You built more crunch than your DSL can give you.

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On my LAN I have 2 wirelesss N boxes running headless. Then 2 boxes with the NIC wired to the wireless router. For months I tried to figure out the logic behind the router transfers to the LAN. On my system the wireless boxes have more successful work requests and download faster than the wired boxes. They all use the same router. No one has explained why to me yet. Don't think anyone knows the answer. I just accept that is the way it is.

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Boinc....Boinc....Boinc....Boinc....

Rate split between wired and wireless - smoke and mirrors.

There has been a trend to biasing available bandwidth on mixed mode routers to the wireless device, this based on the belief that the wireless device is a temporary client and needs to get its data NOW, but the wired device is "always there", so its less important to have a high throughput.
Other things come into play, such as internally the router may have a wired hub not a wired switch, a hub simply shares the bandwidth, but a switch applies a bit of intelligence to the way that bandwidth is shared. So if your router has a hub inside and you have three PCs wired to it each PC will get about a third of the bandwidth all the time (and it will be a fairly constant and accurate third), but if it has a switch an only one of those three PCs is talking then it gets nearly all the bandwidth, but only for the duration of its conversation. Another thing to remember is that a hub only allows data to be passed at the rate of the slowest device, so if you have three PCs, two with 100Mb NICs and one with a 10Mb NIC you will only get 10Mb from the hub (and I've seen a lot of PCs with 1Gb NICs that default to 10Mb and are real pigs to get set to 1Gb).

One final thing on how routers think, some are set up to almost ignore a NIC they think is being promiscuous, so if one NIC is always passing defective packets it will get a much lower share than one that is always passing good packets - one of my PCs had was poorly configured and every time another one talked it tried to interrupt with a collision packet message, the hub I had at the time just passed this to the router this resulted in really bad network performance, replacing the hub with a switch stopped the problem and showed me which PC was the root of the problem, the cure was replacing the on-board NIC with a separate card.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?