Why is the upload speed for Internet connections always so much slower than that for downloads? I have to send a lot of large pictures to clients and it is faster to do this at Starbucks than at home with my DSL line! And why does my Wi-Fi router say 108Mbps when I'm lucky to get a fraction of that?
What you are experiencing with your DSL line is the difference between asymmetric connections with differing up/down speeds, and symmetric ones, where bandwidth is the same in both directions. Most home DSL lines are asymmetric, with uploads much slower than downloads, since ASDL allows for voice connections on the same line. Symmetric DSL is also available, but is more expensive and requires a dedicated line. Similarly, dedicated T1/T3/T+ lines are symmetric. T-series lines are even more expensive than SDSL, and offer speeds starting at 1.5Mbps. Businesses are the primary users of both SDSL and T lines, since they may be hosting a Web site, or have a large number of users sharing a line.
ADSL typically supports data transfer rates from 1.5 to 9Mbps downstream, but only 16 to 640Kbps upstream. Upload rates vary by provider, but are usually 15 to 50 percent of download speeds. That superfast-sounding 1.5Mbps DSL line you're paying extra for may be only giving you 125Kbps for uploads -- about three times as fast as dialup! The kicker is that all T-Mobile Hotspots (such as Starbucks) use at least T1 lines, so assuming you're not sharing the line with a lot of other users, your upload speeds will indeed be much faster at a hotspot than at home.
A side note is that cable and cellular modem data rates are also asymmetric. Cable modem standards provide for a maximum of 30Mbps downstream and 10Mbps up, but this is divided between all users in your area, and individual rated speeds are typically 500Kbps-2.5Mbps down and 256-500Kbps up. For cellular carriers, there is only so much space in the wireless frequency bands they own, so they purposely divide the limited number of "slots" unevenly between up and down data. Most people do a lot more downloading than uploading, so more slots get allocated to downloads.
To measure the real-world upload and download speeds you are getting from any of these connection types, use CNET's Bandwidth Meter.
And what about those Wi-Fi speeds? Sometimes we can get blinded by the numbers on the router box: 108Mbps, 125Mbps, or even 240Mbps with the latest generation of MIMO routers. Actual data rates are always going to be much less, but just how much throughput should you expect to get under real-world conditions?
The rule of thumb is that you'll start with about half the stated throughput. So for a plain vanilla 54Mbps 802.11g, we'd be happy to get 27Mbps out of it, and double that for an enhanced-g 108Mbps router. Then you need to cut that number even further depending on the distance from your router, the number of simultaneous users, and whether you're using encryption. Throughput drops dramatically with distance, as signal strength decreases. So even with a 108Mbps router, in our house we would get barely 10-20Mbps in the upstairs rooms, even less with encryption.
Similarly, simultaneous users will cut available throughput. Home routers have only ONE Wi-Fi radio, which must maintain communication with ALL the Wi-Fi clients attached to it. So even if all equipment were in the same room at maximum signal strength, two clients downloading large files at the same time would cut throughput for each by more than 50 percent, since there is also overhead involved. And throughput will be shaved even more when you are running mixed networks of different types of clients, such as 802.11b, g, and enhanced-g, or if you are in range of neighboring Wi-Fi nets or 2.4GHz cordless phones, which can cause interference.
What all this means is that to get the maximum throughput under any given load, the best strategy is to start out with as fast a router as you can buy. Starting out with a 240Mbps router like the Linksys SRX400 won't actually give you 240Mbps throughput, but it WILL give you nearly double the performance of a typical 108Mbps router.
What you are experiencing with your DSL line is the difference between asymmetric connections with differing up/down speeds, and symmetric ones, where bandwidth is the same in both directions. Most home DSL lines are asymmetric, with uploads much slower than downloads, since ASDL allows for voice connections on the same line. Symmetric DSL is also available, but is more expensive and requires a dedicated line. Similarly, dedicated T1/T3/T+ lines are symmetric. T-series lines are even more expensive than SDSL, and offer speeds starting at 1.5Mbps. Businesses are the primary users of both SDSL and T lines, since they may be hosting a Web site, or have a large number of users sharing a line.
ADSL typically supports data transfer rates from 1.5 to 9Mbps downstream, but only 16 to 640Kbps upstream. Upload rates vary by provider, but are usually 15 to 50 percent of download speeds. That superfast-sounding 1.5Mbps DSL line you're paying extra for may be only giving you 125Kbps for uploads -- about three times as fast as dialup! The kicker is that all T-Mobile Hotspots (such as Starbucks) use at least T1 lines, so assuming you're not sharing the line with a lot of other users, your upload speeds will indeed be much faster at a hotspot than at home.
A side note is that cable and cellular modem data rates are also asymmetric. Cable modem standards provide for a maximum of 30Mbps downstream and 10Mbps up, but this is divided between all users in your area, and individual rated speeds are typically 500Kbps-2.5Mbps down and 256-500Kbps up. For cellular carriers, there is only so much space in the wireless frequency bands they own, so they purposely divide the limited number of "slots" unevenly between up and down data. Most people do a lot more downloading than uploading, so more slots get allocated to downloads.
To measure the real-world upload and download speeds you are getting from any of these connection types, use CNET's Bandwidth Meter.
And what about those Wi-Fi speeds? Sometimes we can get blinded by the numbers on the router box: 108Mbps, 125Mbps, or even 240Mbps with the latest generation of MIMO routers. Actual data rates are always going to be much less, but just how much throughput should you expect to get under real-world conditions?
The rule of thumb is that you'll start with about half the stated throughput. So for a plain vanilla 54Mbps 802.11g, we'd be happy to get 27Mbps out of it, and double that for an enhanced-g 108Mbps router. Then you need to cut that number even further depending on the distance from your router, the number of simultaneous users, and whether you're using encryption. Throughput drops dramatically with distance, as signal strength decreases. So even with a 108Mbps router, in our house we would get barely 10-20Mbps in the upstairs rooms, even less with encryption.
Similarly, simultaneous users will cut available throughput. Home routers have only ONE Wi-Fi radio, which must maintain communication with ALL the Wi-Fi clients attached to it. So even if all equipment were in the same room at maximum signal strength, two clients downloading large files at the same time would cut throughput for each by more than 50 percent, since there is also overhead involved. And throughput will be shaved even more when you are running mixed networks of different types of clients, such as 802.11b, g, and enhanced-g, or if you are in range of neighboring Wi-Fi nets or 2.4GHz cordless phones, which can cause interference.
What all this means is that to get the maximum throughput under any given load, the best strategy is to start out with as fast a router as you can buy. Starting out with a 240Mbps router like the Linksys SRX400 won't actually give you 240Mbps throughput, but it WILL give you nearly double the performance of a typical 108Mbps router.
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