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Why is upstream so slow compared to downstream?

Posted on 2006-06-12
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On a cable modem, in general?

What does the future hold for broadband upstreams?

Did dialup reach it limits in 1999?

References are a plus =]
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Question by:YoungBonzi
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by:callrs
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Home networks are not meant to be servers, in the ISP's view. Infact, some ISP's forbid you to run a server (so I've read).
The typical home user is expected to do connect to the net to RETRIEVE info, not send out massive files at super high speeds.
Thus the upload limits. Lowers the ISP's costs as well, giving you a lower cost than the businesses whose upload speeds are greater.

But if you want higher upload speed, just pay what businesses pay :).

My download & uploads speeds doubled over a year ago....my download speed went way up again this year! :) For the same price.
I still gotta check my new upload speed.

The future of broadband is faster upstreams of course. As technology improves, the more the ISPs can give us in bandwidth for the same basic price.
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by:mnb93
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It's because they don't care about servers, and give you the upload you need to be able to send back enough SYN packets (to get to up to your max down speed)
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by:YoungBonzi
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Are they simply limiting it or is there some kind of techinical issue? Because I don't see why market competition wouldn't have pushed some providers to offer an equal up/down ratio by now.
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by:callrs
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They are simply limiting it. E.g. Rogers Cable Extreme has I think double the upload/download speed of Rogers Regular.
Sympatico (DSL here) regular has much greater upload speed than Rogers, at same or lesser price, but Rogers hasn't pushed its upload speed up.

Equal up/down may be still a long way away (say, 5 or 10 years...) for home users. But just think: if they doubled the upload speeds once, they may well again within a few years. So it's either market forces, technology, lower costs, or a combination that's giving us more for less. Like with computers!

And the forced limits may keep increasing until they reach the technical limits, when time comes that holding back bandwidth no longer makes practical sense -- i.e. if little extra strain is placed on the system with or without forced limits.

Currently, if they allowed equal upload width, it may strain the system. Don't quote me on that...I'm guessing. Who knows what the technical limits are, whether or not they can remove the caps without incurring much extra costs....lets interview the ISPs. :-D

Another thing to consider: if they up the cap, then it may slow things down if the system gets overloaded. (Again I'm theorizing here.)
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by:callrs
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"The system" meaning the Internet hardware etc., not your computer which can handle 100 megabits / second (or now even 1Gigabits/s) transfer rate.
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by:mrandyman
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Good afternoon,
I found the following excerpt from http://fetchsoftworks.com/FetchWebHelp/Contents/Tutorial/SlowUploads.html

For many users, uploading files is quite a bit slower than downloading files. This is usually normal, because most high-speed Internet connections, including cable modems and DSL, are asymmetric — they are designed to provide much better speed for downloading than uploading. Since most users spend much more time downloading (which includes viewing web pages or multimedia files) than they do uploading, high speed Internet providers have designed their systems to give priority to downloading. So if your upload speed appears to be slower than your download speed, this is probably expected.

If you want to read more just follow the link above.  I think it is a good explanation to your question.
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by:bk_jreinstein
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Hi,

Broadband connections are generally asymmetric i.e., that the speed at which you download information from the Internet ( i.e. receive information such as email or web pages) is different from the speed at which you upload (i.e. send information to the Internet such as email, requests for web pages). Typically upload speeds are slower than download speeds.

Hope I helped.
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by:bk_jreinstein
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And also:

Shared bandwidth could result in slowdowns during periods of heavy demand in a given neighborhood.
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by:bk_jreinstein
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The reason uploading is slower is because your internet service provider (e.g. Comcast, Qwest) will usually give you a much higher download speed than upload speed for your internet connection.

Over the past year, cable and DSL broadband providers alike have touted their increased download speeds, but little has been made of upload speeds. Two providers, Verizon Communications and Cablevision, do offer relatively fast upload services in many of their markets--and upload speeds elsewhere have increased modestly over time.
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by:YoungBonzi
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Hmm..I'm not sure if everyone understands my question. I understand that the up/down speeds are asymmetrical. I'm just trying to understand the technical reasons behind it.

I don't see how a 5000/384 cap is different from a 2692/2692 cap. Do they not both take up the same amount of bandwidth?

The reasoning that people download more than they upload would mean that in order to save bandwidth, ISPs would have lower downstream speeds and raise upstream speeds, since the upstream will mostly go unused.

If everybody says that the speeds are set up the way they are with most upstreams capped out at around 45k/s, just because that's the way ISPs want it, then I'll have to go along with that (I can't find the reason online). But it doesn't seem very logical to me. I suspect there must be some issue with the infrastructure of the net, or the "backbone" as I've heard it called.
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by:callrs
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>>"I don't see how a 5000/384 cap is different from a 2692/2692 cap"
See, users want fast downloads. 90% of the people don't give a *(&)*(* about how fast their buddys or strangers get their file. It's a ME ME world, people want things faaaaaaast. LOL , excuse my language! So the ISPs fulfill the mainstream desire for fast downloads, perhaps at the expense of uploads. I don't know the technical issues behind the cap. I'm looking at it from a social perspective...

Home users generally are downloaders -- I think you would pay more attention to how much & how fast you are getting your files than you are about sending them out. Am I right? Do you really want to wait forever to download the new Linux distro or SP2? Aren't you amazed when 1meg files arrive almost instantly? And even if you care about uploads, if you are like me, the cap mainly irritates when you're sending files to your chat buddies or uploading a 1Gig file to sendspace.com (omg, sendspace capped it to 300Meg now! O the irony...).

So it makes good business sense to cater to the majority. For the minority who want higher uploads, tough luck  -- you'll have to pay extra or just get a second line like DSL + Cable.

ISPs want the majority to be happy customers. So there's little chance of equalizing the upload/download unless TECHNOLOGY makes it so there's no technical reason to allow the caps. Once technology advances to the point of awesome bandwidth without affecting the health of the Internet system, then the ISP's seem happy to pass the speeds on to us....it's the age of digital video, higher speeds are a necessity & the ISPs I believe are itching to increase the bandwidth for everyone.

Over a year ago my DSL download AND upload speed more than doubled to 300/80 kB/s (about 2.5Meg kb/s)  This year its  500/82 kB/s. But the price has not increased. Gotta love that! :)

P.S. Locally, for same level but lower price, DSL upload speeds are much higher than the Cable upload speeds: 384kbs vs 640kb. I've tried both Cable & DSL; I prefer DSL partially because I think that 384 upload speed is R I D I C U L O U S L Y low & VERY irritating.  640 is a 66% increase! Gotta love that! So see if you can get DSL...there's always fantastic deals around due to the competition.
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by:JohnBPrice
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>>I don't see how a 5000/384 cap is different from a 2692/2692 cap. Do they not both take up the same amount of bandwidth?

Yes and no, depending on your type of DSL.  There are a number of different types of DSL some can dynamically allocate bandwidth based on need.  My business 768K-capped DSL is 768 up, or 768 down, or a mix adding up to my 768K cap.  See page 9 at http://www.alliedtelesyn.com/corporate/media/whitepapers/dsl_wp_c.pdf
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No technical reasons, just business reasons.  Why would a buisness pay $400 for a T1 when they could have DSL/Cable for $50 (or less)?  This is why SDSL (last time I checked) was as expesnive as leased circuts.

You also have the issue where DSL and Cable are best effort.  They may advertise x/y, but there is no guarantee that they will deliver that.

Technically 5000/384 has the same total bandwidth as 2692/2692.  However, they provide a different amount of throughput for the end user.  Say you want to download a 5 MB file.  You are doing to receive just over 5BM of data, but you are only going to send a few 100K.  It will take less time to receive the file on a 5000/384 link than it will on a 2692/2692 link, in fact about 1/2 of the time.  As has been stated, most  home users download more than they upload so most home users will get a "better experience" with the asymmetrical link of high/low, than they would with a symmetrical link of med/med.
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by:JohnBPrice
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>>No technical reasons, just business reasons.
They are both.  To implement dynamically assigned bandwidth, you need different equipment.  Equipment costs money.  For DSL, it is easier to provide dynamically assigned bandwith for customers who want it, since it is a point to point connection and they can mix them at their DSLAM.  For Cable, it is more difficult to implement dynamically assigned bandwidth since you have essentially bigger LANs which might all have to be upgraded together.  It also might be highly technical.  Bandwidth depends partly on how much power you use to drive the line at the head end, the cable company has more power available than might be preactical for set top boxes to transmit with.
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by:callrs
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Footnote to my last comment: Only disadvantage to my DSL line:  Dynamic IP address sometimes changes EVERY FEW MINUTES. I saw it do this all night once. IP is often stable, but when it's not, then any server hosted on my computer can become unreachable to outsiders for hours. (A dynamic
 DNS client checks, every 10 minutes, & updates my IP to match a domain name). With Cable, IP rarely changed.
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by:CarlosMMartins
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As ADSL companies try and push more and more stuff on its lines, I think it's easy to understand why their pushing for higher download speeds.

In here (Portugal) it's now common to have 8 or 16 Mbits download (with 265-400kbits up).
Of course, those are the same companies that are now trying to push TV channels over the ADSL connection...

As for faster uploads, I don't know of any common available solutions here. In the Netherlands I have a colleague that has a 5Mb up / 1Mb down connection.

The keypoint is that "ADSL" stands for *Asymetrical*. I know there are several SDSL (symetrical) connections available for enterprises, where the up/down bandwidth is the same, but it's not available for "home" customers.

On cable, for a long time their infrastructure was oriented for a "central->home" transmission, it was always easier for them to send data to your home than the opposite. I still remember the time I'd do the upload thru a regular phone modem, and get the downloads back through the cable modem - because the cable network was only "one way".

Today, I don't think that is the case, and up/down difference is mainly because most people spend most time downloading stuff than uploading.
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by:giltjr
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JohnBPrice:  What does having different upstream and downstream speeds have to do with dynamically allocated bandwidth? However, you can dynamically change link speeds on a leased circut, just like you can with DSL and both have limitations.  Fractional T1 and E3 are examples of where you can start with lower speeds and allocate more bandwitdh (up to the limitations of a T1 or E3) as needed.  DSL does not allow unlimited dynamic bandwidth allocation, the DSL modems to have limitations so I can crank a DSL link up to the same speeds as leased circuts.

callrs: Some ISP's do allow you to get assigned static IP addresses for DSL services either as a extra cost on a "home" service or part of the cost of business class DSL.  My ISP (Earthlink) in my area (near Washington, D.C.) charges $15 extra a month for static a IP address.
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by:JohnBPrice
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>>What does having different upstream and downstream speeds have to do with dynamically allocated bandwidth?

My vague understanding is that data is transmitted in different frequency bands on the wire.  In most home DSL & Cable, most bands are allocated to downstream data, some for upstream, and that doesn't change.  If, however, you have dynamically allocated bandwith (not the cap, but how the bandwidth on the wire is allocated to upstream vs. downstream), your DSL modem can reassign bandwidth from downstream to upstream or visa versa.  It is neither symetric nor asymetric, or perhaps it is both.  It is not commonly used for home connections, but in office buildings where the DSLAM may be very close (even in your building), you can get really high data rates both ways.
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by:callrs
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$15 U.S a month extra? Yikes. EE kept me so busy for this past month, I haven't even earned enough to pay my Internet bill! :-p
I've seen a $10 rate here before. But I'll have to pass & even keep switching ISPs to stretch few dollars to the best deal..


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by:giltjr
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JohnBPrice:  What DSL does is create mutliple channels. There is a fixed number of channels that DSL supports.  Then depending on how far you are from the CO changes the number of usable channels.  However, DSL channels are not full duplex channels like a T1/T3 channles are.  The channles are then allocated as either downstream or upstream.  However, there is no real technical reason that there has to be more downstream channels.  The main reason is that most home users receive more data than they send.  As there is a fixed number of channels, if upstream and downstream were equal bandwidth, most home users would get slower download/pageload times.

Think of it this way.  DSL is like having 10 single lanes roads.  You can say that you want 5 going north and 5 going south, or 7 going north and 3 going south. You can change (well not you as the user, but the service provide) the number of lanes you have going in which direction.  But no matter what you are limted to 10 lanes and you need at least one lane to go in the oppsite direction of the others.  If, for some weird reason, 90% of your traffic was north, then you would want to have 9 northbound lanes and 1 southbound lane, or maybe 8/2.  This way you have smooth traffic flow.

Now a T1 is more like having up to 24 two lane roads.  You can subscribe to anywhere from 1 to 24 of these two lane roads, but you will always have and equal number of lanes going north and south.


Reference that may make is clearer than I can:  http://en.wikipedia.org/wiki/Digital_Subscriber_Line
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by:JohnBPrice
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Well, I can't remember where I read it, but it was basically that with some types of DSL, the channels could be reassigned on the fly as downstream vs upstream.
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by:cbromley33
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Wow, this has turned into a big long discussion.  For the most part, gilt is correct.  It is mostly for business reasons.  

Why?  Well, considering how incredibly easy it is to have your own private web server, your own FTP server or any other kind of server, they have to limit the upload speed so as not to consume bandwidth.

Imagine this:

All of a sudden, everyone had the same upload speeds as download speeds.  Considering cable companies work much like large lans, and your connection isn't dedicated to just you like a DSL line connection is, you share that bandwidth with however many other customers are on your segment.  If just ONE of your neighbors decided to host a porn web server, the bandwidth consumed by this would degrade everyone's connection on your segment.  Add to that just 3 people on your segment using a p2p sharing program to share all of their movies and mp3s 24 hours a day... and just 1 user running an FTP site, and the bandwidth gets hammered.  By keeping these caps low, they discourage running such servers on their network, thereby providing a better experience for the majority of customers.

If cable companies ever allow same upload as download, and it's at a good speed, you will see a serious decline in the number of web hosting providers out there as a lot of people set up their spare machines as web servers for their sites instead of paying someone else to host them.
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by:bk_jreinstein
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cbromley here is talking about the shared bandwith problem which I posted (I of course did not elaborate :)). Whoever you share the bandwith with can eat up a lot of bandwith thereby making your speed like that of a dial-up connection.
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by:nsstone
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Hmm .. writing a paper for yor IT course, eh?

Simply put, upstream is smaller than downstream because no web site cares what you have to say, as much as you care what they have to say.

Havaniceday
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by:YoungBonzi
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This article (http://www.economist.com/displaystory.cfm?story_id=6794156) from the Economist confirms my suspicion that there is a technical reason behind the up/down ratio. You might have to be a subscriber to read it so I'll include an excerpt:

"By way of infrastructure, full-scale participatory media presume not so much the availability of the (decades-old) internet as of widespread, “always-on”, broadband access to it. So far, this exists only in South Korea, Hong Kong and Japan, whereas America and other large media markets are several years behind. Indeed, even today's broadband infrastructure was built for the previous era, not the coming one. Almost everywhere, download speeds (from the internet to the user) are many times faster than upload speeds (from user to network). This is because the corporate giants that built these pipes assumed that the internet would simply be another distribution pipe for themselves or their partners in the media industry. Even today, they can barely conceive of a scenario in which users might put as much into the network as they take out."

The writer goes on to say that the new Internet business model will cater to users who desire more upload speeds. So to say that ISPs just don't want us to be able to upload as fast as we download isn't true. But to say that they simply cannot do so is...so does anyone know what these techinical limitations of the infrastructure are?


P.S. I'm not a student, just wondering why things are the way the are. And I like references because comments like "Simply put, upstream is smaller than downstream because no web site cares what you have to say, as much as you care what they have to say." aren't going to satisify my curiosity at all.
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by:giltjr
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There is none.  It is really more of a business decision based on technical knowledge of usage patterens.  

Think about this.  What is the #1 thing that most home users do on the Internet?  Easy, access web sites.  When you access a web site how much data to you  GET from the site?  The last numbers I saw say the avg web page downloads close to 200K of data.  If 190K is static it can be cached and so only 10K get downloaded.  However, how much data do you send to get that page?  On average it is less that 100 bytes.  So you send 100 and get 10,000.  That is a 100:1 ratio.  You avg. DSL connection may be 1500/384 which is about a 4:1 ratio.  My guess is today with all of the advertisement that most web pages are sending down more than 10K of data.

Get a packet capture tool (I suggest Ethereal http://www.ethereal.com) start it up and see the difference between what you send and what you receive.  You may want to check the box that says only to capture the first 64 bytes of each packet so you collect less data.  Run it for a while.  After you stop, click on statistics and converstations.    Look at the difference between what is sent to you comparied to what you send out.

Technically the network does not care about direction of traffic in most cases.  The only case where it does is dial-up connections.  It has the same bandwidth avalaible on the wire in both directions.  It is just because you normally receive more that you send you get better (shorter/faster) load times if you have more bandwidth to you.
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by:callrs
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Based on the quote you supplied, ISPs expectations of the typical user (downloader vs uploader) has given us the infrastructure we have. But now the expectations have changed, and so will the future, as my write-ups above envision. Have you read about what fiberglass can do? With that infrastructure in place throughout the system, I wonder if there'd be any technical reason left to limit the bandwidth.

However, we still don't have a solid reference as to how much bandwidth those "pipes" now in place can actually support. Are the ISPs limiting the bandwidth needlessly or not? Without the technical facts, how can we be sure?

But as the doubling & quadrupling of bandwidth proves: ISPs want to increase the bandwidth for the home user: technology has indeed limited them from doing so. But technology is ever opening up those limits to a bold new digital age. Computer chip makers, car designers, engineers -- just about anyone, is wanting to make things better. And when clear heads prevail, they go do it.


Other reasons:

"Why is upstream so slow compared to downstream?" is, besides the technical limits, rooted in assumptions. Like the famous assumption that 1Meg of computer memory is plenty or that the IP addressing scheme is sufficient.

It's also rooted in inertia and a resistance by the majority to think & act against the tide. Witness, for example, the prevalence of QWERTY against the superior DVORAK: how many so-called schools & colleges even teach Dvorak?

And it's also rooted in the the "money" mentality vs. "true practical benefit". Such creed has caused untold misery & devastation to the wealth of family, ecology, society, personal development, and more.


It takes a visionary to go beyond assumptions & to design systems from the root up to stand the test of time...like the great pyramids. A legacy to leave 'for ever'.



-R.S.
2006-06-17


giltjr's highway analogy sounds plausible. But it may or may not  be true. Often what seems logical, isn't.
cbromley33's high-use-by-neighbor argument seems valid for cable (not DSL) for now. I'm hoping though for the technology that will make limits virtually obsolete. : )

*shucks*, Delayed the garden again to write this. :O  A month -- my first month -- at EE & now at 90K:   100K by tomorrow?!
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by:YoungBonzi
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Thank you for your thoughts. They all make sense. If anyone finds an article or anything about this, please let me know about it!

Thanks again!
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