Who has control of the internet bandwidth?
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An interesting question was raised today by someone i know, and that is "Who controls the bandwidth on the internet" Using myself as a example, I connect to the interest through a 56K modem, via a phone line which is rented from British Telecom. My ISP is Freeserve. Factors with regards to the bandwidth is 1. The maximum speed which the phone line can operate. 2. Limited enforced by ISP i.e. Freeserve 3. Limits enforced by Telecommunications company, i.e. British Telecom. From using the internet, its seams clear you cannot achieve the 56K potential of the modem, due to the line quality, and method which the data is transmitted through the phone line. Since data is converted from digital to analogue via modulation, then vice versa at the other end, there is potential of data being corrupted alone the lines and hence data can often be retransmitted, thus reducing the transfer rate. There are most probably other reasons why we can never achieve the 56K transfer rate, which some people may wish to bring to mine and no doubt other peoples attention in this thread. I have no idea whether the ISP or Phone company restrict the bandwidth when they see fit. But I would be very interested to find out. As far as I am currently aware the only limits are 1. The quality of the phone line which may introduce noise thus reducing the transfer rate 2. The congestion of the internet traffic
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An interesting question was raised today by someone i know, and that is "Who controls the bandwidth on the internet" Using myself as a example, I connect to the interest through a 56K modem, via a phone line which is rented from British Telecom. My ISP is Freeserve. Factors with regards to the bandwidth is 1. The maximum speed which the phone line can operate. 2. Limited enforced by ISP i.e. Freeserve 3. Limits enforced by Telecommunications company, i.e. British Telecom. From using the internet, its seams clear you cannot achieve the 56K potential of the modem, due to the line quality, and method which the data is transmitted through the phone line. Since data is converted from digital to analogue via modulation, then vice versa at the other end, there is potential of data being corrupted alone the lines and hence data can often be retransmitted, thus reducing the transfer rate. There are most probably other reasons why we can never achieve the 56K transfer rate, which some people may wish to bring to mine and no doubt other peoples attention in this thread. I have no idea whether the ISP or Phone company restrict the bandwidth when they see fit. But I would be very interested to find out. As far as I am currently aware the only limits are 1. The quality of the phone line which may introduce noise thus reducing the transfer rate 2. The congestion of the internet traffic
I would expect the modulation technique to have the biggest influence . The bandwidth on offer (for UK analgue phones) is I think 300Hz to 3KHz (But it may be smaller) The modulation technique allows them to send more than one bit per baud , I think they use one of the varients of phase shift keying . Now this means that for our 2.5kHz real bandwidth we can send 56K bits per second . when the line degrades leading to a higher error rate then the bits per second are reduced , this may be from the sending end requesting resends or it may be that they negotiate a different modulation technique , I do not know . After the data gets to the ISP then it has control over the rate at which it is processed , as the incomming buffers fill then a signal must be sent back to your modem telling it to hang fire . So at that point the ISP has control , but they cannot go above the limits imposed by the modulation technique and the protocol used . When you get to fibre , the theoretical bandwidth is infinite (= bloody big in practical terms). So then the carrier has to limit how much you have , it probably does so in much the same way as for the modem , throttling the throughput and signalling back to the sender not to send any more . If you look at a serial port you will typically see hardware connections (RTS,DTS,DSR,DTR) which are meant just for this handshaking of data , but there is also provision for software methods of handshaking/throttling the data flow. Am I the only one forever playing catch up with technology , while all the juicy opportunites keep rolling by ?
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I would expect the modulation technique to have the biggest influence . The bandwidth on offer (for UK analgue phones) is I think 300Hz to 3KHz (But it may be smaller) The modulation technique allows them to send more than one bit per baud , I think they use one of the varients of phase shift keying . Now this means that for our 2.5kHz real bandwidth we can send 56K bits per second . when the line degrades leading to a higher error rate then the bits per second are reduced , this may be from the sending end requesting resends or it may be that they negotiate a different modulation technique , I do not know . After the data gets to the ISP then it has control over the rate at which it is processed , as the incomming buffers fill then a signal must be sent back to your modem telling it to hang fire . So at that point the ISP has control , but they cannot go above the limits imposed by the modulation technique and the protocol used . When you get to fibre , the theoretical bandwidth is infinite (= bloody big in practical terms). So then the carrier has to limit how much you have , it probably does so in much the same way as for the modem , throttling the throughput and signalling back to the sender not to send any more . If you look at a serial port you will typically see hardware connections (RTS,DTS,DSR,DTR) which are meant just for this handshaking of data , but there is also provision for software methods of handshaking/throttling the data flow. Am I the only one forever playing catch up with technology , while all the juicy opportunites keep rolling by ?
Apart from the classic modem, the only other option for me is:- 1.A private connection, which David Wulff mentioned the other day 2. ISDN 3. Satellite. But for me, ISDN costs more than ADSL, and on top of that you have to pay for the calls on the dual lines. Basically its really expensive. Satellite isn't really practical, from what I have found out, unless your just downloading large files (since the dish can only receive and not transmit) One day I and Dave W will be blessed with ADSL, will our prayers be one day answered??? :~ Take the hint British Telecom!! :mad: "Lifes a lemon and I want my money back"
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An interesting question was raised today by someone i know, and that is "Who controls the bandwidth on the internet" Using myself as a example, I connect to the interest through a 56K modem, via a phone line which is rented from British Telecom. My ISP is Freeserve. Factors with regards to the bandwidth is 1. The maximum speed which the phone line can operate. 2. Limited enforced by ISP i.e. Freeserve 3. Limits enforced by Telecommunications company, i.e. British Telecom. From using the internet, its seams clear you cannot achieve the 56K potential of the modem, due to the line quality, and method which the data is transmitted through the phone line. Since data is converted from digital to analogue via modulation, then vice versa at the other end, there is potential of data being corrupted alone the lines and hence data can often be retransmitted, thus reducing the transfer rate. There are most probably other reasons why we can never achieve the 56K transfer rate, which some people may wish to bring to mine and no doubt other peoples attention in this thread. I have no idea whether the ISP or Phone company restrict the bandwidth when they see fit. But I would be very interested to find out. As far as I am currently aware the only limits are 1. The quality of the phone line which may introduce noise thus reducing the transfer rate 2. The congestion of the internet traffic
Do a traceroute to some internet ip. The first hop is the router on the other side of your modem connection. Now do a ping -l 1024 router_ip (record average time as t1) ping -l 2048 router_ip (record average time as t2) Now on an average, your modem connection supports 1024 bytes per (t2-t1) ie, 1024 * 8 / (t2-t1) is your approx b/w. Please note: - this is a very crude method. - this is the data rate for your data. actual bit rate will be higher because there are 3 bits extra (stop and start bits) per byte and the IP framing. Hope this helps. Thomas
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An interesting question was raised today by someone i know, and that is "Who controls the bandwidth on the internet" Using myself as a example, I connect to the interest through a 56K modem, via a phone line which is rented from British Telecom. My ISP is Freeserve. Factors with regards to the bandwidth is 1. The maximum speed which the phone line can operate. 2. Limited enforced by ISP i.e. Freeserve 3. Limits enforced by Telecommunications company, i.e. British Telecom. From using the internet, its seams clear you cannot achieve the 56K potential of the modem, due to the line quality, and method which the data is transmitted through the phone line. Since data is converted from digital to analogue via modulation, then vice versa at the other end, there is potential of data being corrupted alone the lines and hence data can often be retransmitted, thus reducing the transfer rate. There are most probably other reasons why we can never achieve the 56K transfer rate, which some people may wish to bring to mine and no doubt other peoples attention in this thread. I have no idea whether the ISP or Phone company restrict the bandwidth when they see fit. But I would be very interested to find out. As far as I am currently aware the only limits are 1. The quality of the phone line which may introduce noise thus reducing the transfer rate 2. The congestion of the internet traffic
In the US modems are limited by the FCC to 53 kbps, despite the 56K terminology. Apparently using that last 3k can potentially interfere with other services that have priority over public Internet access. Considering the fact that the POTS infrastructure is designed to accomodate a 2KHz bandwidth, that's still not bad!:-D Word of the day: Rotundacrat
Extra Credit will be awarded for: Quasimobo... -
An interesting question was raised today by someone i know, and that is "Who controls the bandwidth on the internet" Using myself as a example, I connect to the interest through a 56K modem, via a phone line which is rented from British Telecom. My ISP is Freeserve. Factors with regards to the bandwidth is 1. The maximum speed which the phone line can operate. 2. Limited enforced by ISP i.e. Freeserve 3. Limits enforced by Telecommunications company, i.e. British Telecom. From using the internet, its seams clear you cannot achieve the 56K potential of the modem, due to the line quality, and method which the data is transmitted through the phone line. Since data is converted from digital to analogue via modulation, then vice versa at the other end, there is potential of data being corrupted alone the lines and hence data can often be retransmitted, thus reducing the transfer rate. There are most probably other reasons why we can never achieve the 56K transfer rate, which some people may wish to bring to mine and no doubt other peoples attention in this thread. I have no idea whether the ISP or Phone company restrict the bandwidth when they see fit. But I would be very interested to find out. As far as I am currently aware the only limits are 1. The quality of the phone line which may introduce noise thus reducing the transfer rate 2. The congestion of the internet traffic
I guess the point I was making was. If I download a file, I am lucky to get a download speed of 5kb/s. One would first think that a 56K modem would allow you to download at 56k. Obviously this isn't the case, due to the phone lines etc as already discussed. However when a download is sometimes started I can get a transfer rate of 11kb for example, which may not sound like much to you broadband people, but its enough to make me rub my eyes in disbelief. This burst transfer rapidly decreases down to the regular 5kb. Seams as though someone is throttling back the transfer. Hence why I am asking if my ISP or phone company is squeezing the life out of my transfer rate. -- Peter "Lifes a lemon and I want my money back"
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I guess the point I was making was. If I download a file, I am lucky to get a download speed of 5kb/s. One would first think that a 56K modem would allow you to download at 56k. Obviously this isn't the case, due to the phone lines etc as already discussed. However when a download is sometimes started I can get a transfer rate of 11kb for example, which may not sound like much to you broadband people, but its enough to make me rub my eyes in disbelief. This burst transfer rapidly decreases down to the regular 5kb. Seams as though someone is throttling back the transfer. Hence why I am asking if my ISP or phone company is squeezing the life out of my transfer rate. -- Peter "Lifes a lemon and I want my money back"
Peter Mayhew wrote: guess the point I was making was. If I download a file, I am lucky to get a download speed of 5kb/s. One would first think that a 56K modem would allow you to download at 56k. Obviously this isn't the case, due to the phone lines etc as already discussed. Um, I think you have a few mistakes and misnomers in your logic: 1) Um, if I'm not mistaken, a 56K modem transfers a maximum of 56,000 bits/second. Therefore, the maximum speed you should experience is 7KB/s. In reality, the speed goes down a little more due to TCP/IP handshaking (if you measure from IE alone rather than statistical data from the modem). Your phone line can really handle 56,000bps, but not 56KB/sec.:) 2) Also, if I remember from college, TCP/IP tends to throttle and then pull back when it hits a peak. So, in a way, your transfer speed is never constant. Though, browsers would just average over time and not give you real time speed. 3) If you turned on compression in your modem, the data is really just compressed and still sending at the normal transfer rate. So, it's possible that initial data (like packet headers) can be compressed and therefore give you a high transfer speed. Frank http://www.frankliao.com
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Peter Mayhew wrote: guess the point I was making was. If I download a file, I am lucky to get a download speed of 5kb/s. One would first think that a 56K modem would allow you to download at 56k. Obviously this isn't the case, due to the phone lines etc as already discussed. Um, I think you have a few mistakes and misnomers in your logic: 1) Um, if I'm not mistaken, a 56K modem transfers a maximum of 56,000 bits/second. Therefore, the maximum speed you should experience is 7KB/s. In reality, the speed goes down a little more due to TCP/IP handshaking (if you measure from IE alone rather than statistical data from the modem). Your phone line can really handle 56,000bps, but not 56KB/sec.:) 2) Also, if I remember from college, TCP/IP tends to throttle and then pull back when it hits a peak. So, in a way, your transfer speed is never constant. Though, browsers would just average over time and not give you real time speed. 3) If you turned on compression in your modem, the data is really just compressed and still sending at the normal transfer rate. So, it's possible that initial data (like packet headers) can be compressed and therefore give you a high transfer speed. Frank http://www.frankliao.com
Which means if you get a maximum of 53k (53000 bits/sec) that comes out to 53000bits/8bytes = 6625bytes/sec or 6.6kb/sec MAX at 5kb/sec you're downloading at about 40000 bit/sec Todd Smith
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I guess the point I was making was. If I download a file, I am lucky to get a download speed of 5kb/s. One would first think that a 56K modem would allow you to download at 56k. Obviously this isn't the case, due to the phone lines etc as already discussed. However when a download is sometimes started I can get a transfer rate of 11kb for example, which may not sound like much to you broadband people, but its enough to make me rub my eyes in disbelief. This burst transfer rapidly decreases down to the regular 5kb. Seams as though someone is throttling back the transfer. Hence why I am asking if my ISP or phone company is squeezing the life out of my transfer rate. -- Peter "Lifes a lemon and I want my money back"
Peter Mayhew wrote: However when a download is sometimes started I can get a transfer rate of 11kb for example, which may not sound like much to you broadband people, but its enough to make me rub my eyes in disbelief. I think that if you run a little test, you can figure out why (assuming that you're using Internet Explorer, which is where I've seen the same behavior). Pick a file to download, then wait for a minute or two before telling it where to save the file. Once you've selected a name after waiting for a while, you'll probably see a nice high download rate. Not having purposefully done this, I can't guarantee it. But I think that IE starts downloading before you've given it a filename, then incorrectly calculates the download speed based on the number of bytes it already had before displaying the progress dialog. :confused: John
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Which means if you get a maximum of 53k (53000 bits/sec) that comes out to 53000bits/8bytes = 6625bytes/sec or 6.6kb/sec MAX at 5kb/sec you're downloading at about 40000 bit/sec Todd Smith
Todd Smith wrote: 53000bits/8bytes = 6625bytes/sec or 6.6kb/sec MAX From your calculation, it should be 6625 bits to every byte.:omg: Your math needs some work: ;P 1 baud = 1 bit/sec 1 byte = 8 bits (53000 bits/sec) * (1 byte / 8 bits) = 6625 bytes/sec :-D Frank http://www.frankliao.com
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Peter Mayhew wrote: guess the point I was making was. If I download a file, I am lucky to get a download speed of 5kb/s. One would first think that a 56K modem would allow you to download at 56k. Obviously this isn't the case, due to the phone lines etc as already discussed. Um, I think you have a few mistakes and misnomers in your logic: 1) Um, if I'm not mistaken, a 56K modem transfers a maximum of 56,000 bits/second. Therefore, the maximum speed you should experience is 7KB/s. In reality, the speed goes down a little more due to TCP/IP handshaking (if you measure from IE alone rather than statistical data from the modem). Your phone line can really handle 56,000bps, but not 56KB/sec.:) 2) Also, if I remember from college, TCP/IP tends to throttle and then pull back when it hits a peak. So, in a way, your transfer speed is never constant. Though, browsers would just average over time and not give you real time speed. 3) If you turned on compression in your modem, the data is really just compressed and still sending at the normal transfer rate. So, it's possible that initial data (like packet headers) can be compressed and therefore give you a high transfer speed. Frank http://www.frankliao.com
Ah its now all becomes clear about not achiving 7KB/s, thank you everyone. (sorry for the delay, but i didn't get an e-mail saying that some people replied to my comment!) --- Peter M