Cable Speeds
It is not cut and dry - read whyDepending on the provider, the throughput that cable modem users will receive has been advertised to the public to be somewhere between 10 times to 1,000 times faster than dial-up connections to the Internet. Many times, providers will determine the throughput by comparing the maximum data rate support provided by the cable modem with dial-up data rates. For example, if a cable modem system has been developed to support up to 30 Mbps (bits not bytes) downstream and 1.5 Mbps upstream, then the provider will calculate the difference based on a 33.6 or 56k modem. When providers use this approach to pitch their services, they absolutely deceive their potential customers because cable modem throughput NEVER reaches its technological cap. This is true for a user's connection to content accessed from the Internet and from content accessed from the Internet servers located at the provider's headend facilities.
The speed bumps begin at the customer premises. In many cases, the client PC inhibits throughput due to an inability to process fast data rates. For example, a 90-MHz machine may not be able to support incoming data at 5 Mbps. Also on the customer end, the Ethernet 10Base-T connection restricts users to 10 Mbps. Therefore, as long as 10BaseT is the interface, it is impossible to gain throughput exceeding 10 Mbps - no exceptions.
The inhibitors continue onto the network. The network within your neighborhood may slow throughput. The data has to pass through coax, taps, and amps. If those network components are old and shabby, they may affect data transfer. There may exist loose connections or be old and worn and as a result be more susceptible to ingress. Ingress can not only slow throughput but kill a connection altogether. In most cases, providers replace the traditional standard RG-59 coax with RG-6 and replace taps and sometimes add filters before introducing data services. However, this is certainly not going to be a universal practice considering there are more than 20,000 cable operators in the world.
Throughput can also be affected by the number of cable modem users in a given neighborhood and the types of activities those users are engaged in on the network. Cable modem technology utilizes a shared medium in which all of the users served by a node (200-2000 homes depending on the provider) share bandwidth. Therefore, if Joe is the only cable modem user served by his node, then he has access to all of the bandwidth and his throughput to the Internet servers and CMTS (cable modem termination system) should be fairly consistent. On the flip side, if all of Joe's neighbors have a cable modem, then he will see slower data rates. Just as highway traffic moves slower at rush hour because of the number of cars on the road, volumes of users reduce throughput. The scenario becomes worse if all of Joe's neighbors are gobbling bandwidth by viewing streaming media or using their home PCs as servers. Many cable providers watch for traffic within nodes and if a particular node becomes congested, they will add another node in the neighborhood to solve the problem. Obviously, some providers will be lethargic.
The emergence of tiered services will also help control neighborhood congestion. Providers will be able to allocate bandwidth to users, which will place a cap on bandwidth access. This will keep the bandwidth hogs from shafting the neighborhood.
Once the data hits the node, it jumps onto an optical fiber backbone, which carries traffic to the CMTS. While riding the fiber, there are no speed bumps.
When the data arrives at the CMTS, Joe may be subject to misconfigurations or configurations of the CMTS or headend Internet servers that might not provide optimal throughput. There is no documentation that indicates that throughput has ever been affected by misconfigurations at the headend, but the potential exists.
If Joe is accessing content on the Internet that is not cached at the provider's headend, then the access request must travel beyond the cable modem network to the traditional Internet. Whether connected via a dial-up or a cable modem, Joe is going to be subject to all of the speed bumps on the Internet, which include slow and congested routers and servers and the T-1 lines and worse that might be between Joe and his content. Cable modems do not make the Internet a faster network. Instead, they make the connection between the user's PC and the backbone quicker. As the Internet infrastructure is improved accessed content outside of the cable infrastructure will improve. Until then, users will only find the full benefit of Internet access via cable modems through cached content and that content that is served over a private network.
In addition to all of the aforementioned inhibitors, data throughput is bursty. Unlike telco technology, cable modem technology does not support CBR (constant bit rate). Cable modem users are not connected to the backbone at 10 Mbps or 1 Mbps. The data rate is going to bounce up and down during a transfer. For a couple of seconds, a user may be getting 2 Mbps and then suddenly drop to 70 Kbps then jump up to 400Kbps and so on and so on.
The average throughput of this bursty connectivity to the cable headend will depend on the cable modem technology utilized and all of the factors mentioned above. Since all cable plants are different and all activity within a neighborhood node is going to be unique not only in general, but at any given moment, there is absolutely no way to provide a fixed data throughput rate to cable modem service. Testimonials range from users claiming throughputs in excess of 2 Mbps, while others have claimed that their 56k modem provided greater connectivity speeds.
In 99.9% of the cases, cable modem users are getting throughput to the cable headend and to the traditional Internet at speeds greater than that provided by an ISDN connection. A ballpark average (provided reluctantly) for throughput to the Internet would be 500Kbps down and 128Kbps up. For accesses within the cable network, the ballpark average throughput would be 1.5 Mbps downstream and 500Kbps upstream.
While the reference numbers provided may be far below those advertised by a provider, the difference between a 56k or ISDN connection and a cable modem connection at the above mentioned data rates is dramatic. Web pages pop up instantly. Large file downloads are executed in seconds or minutes rather than hours. Streaming audio and video and multi-player gaming is adequately supported. The mean time spent on Internet activities is reduced, allowing the user to do much more in a given time. Despite whether or not the throughput matches what is advertised, for the money, cable modem service is almost always the best value an Internet user can get for a high-speed connectivity to the Internet.
It is not cut and dry - read whyDepending on the provider, the throughput that cable modem users will receive has been advertised to the public to be somewhere between 10 times to 1,000 times faster than dial-up connections to the Internet. Many times, providers will determine the throughput by comparing the maximum data rate support provided by the cable modem with dial-up data rates. For example, if a cable modem system has been developed to support up to 30 Mbps (bits not bytes) downstream and 1.5 Mbps upstream, then the provider will calculate the difference based on a 33.6 or 56k modem. When providers use this approach to pitch their services, they absolutely deceive their potential customers because cable modem throughput NEVER reaches its technological cap. This is true for a user's connection to content accessed from the Internet and from content accessed from the Internet servers located at the provider's headend facilities.
The speed bumps begin at the customer premises. In many cases, the client PC inhibits throughput due to an inability to process fast data rates. For example, a 90-MHz machine may not be able to support incoming data at 5 Mbps. Also on the customer end, the Ethernet 10Base-T connection restricts users to 10 Mbps. Therefore, as long as 10BaseT is the interface, it is impossible to gain throughput exceeding 10 Mbps - no exceptions.
The inhibitors continue onto the network. The network within your neighborhood may slow throughput. The data has to pass through coax, taps, and amps. If those network components are old and shabby, they may affect data transfer. There may exist loose connections or be old and worn and as a result be more susceptible to ingress. Ingress can not only slow throughput but kill a connection altogether. In most cases, providers replace the traditional standard RG-59 coax with RG-6 and replace taps and sometimes add filters before introducing data services. However, this is certainly not going to be a universal practice considering there are more than 20,000 cable operators in the world.
Throughput can also be affected by the number of cable modem users in a given neighborhood and the types of activities those users are engaged in on the network. Cable modem technology utilizes a shared medium in which all of the users served by a node (200-2000 homes depending on the provider) share bandwidth. Therefore, if Joe is the only cable modem user served by his node, then he has access to all of the bandwidth and his throughput to the Internet servers and CMTS (cable modem termination system) should be fairly consistent. On the flip side, if all of Joe's neighbors have a cable modem, then he will see slower data rates. Just as highway traffic moves slower at rush hour because of the number of cars on the road, volumes of users reduce throughput. The scenario becomes worse if all of Joe's neighbors are gobbling bandwidth by viewing streaming media or using their home PCs as servers. Many cable providers watch for traffic within nodes and if a particular node becomes congested, they will add another node in the neighborhood to solve the problem. Obviously, some providers will be lethargic.
The emergence of tiered services will also help control neighborhood congestion. Providers will be able to allocate bandwidth to users, which will place a cap on bandwidth access. This will keep the bandwidth hogs from shafting the neighborhood.
Once the data hits the node, it jumps onto an optical fiber backbone, which carries traffic to the CMTS. While riding the fiber, there are no speed bumps.
When the data arrives at the CMTS, Joe may be subject to misconfigurations or configurations of the CMTS or headend Internet servers that might not provide optimal throughput. There is no documentation that indicates that throughput has ever been affected by misconfigurations at the headend, but the potential exists.
If Joe is accessing content on the Internet that is not cached at the provider's headend, then the access request must travel beyond the cable modem network to the traditional Internet. Whether connected via a dial-up or a cable modem, Joe is going to be subject to all of the speed bumps on the Internet, which include slow and congested routers and servers and the T-1 lines and worse that might be between Joe and his content. Cable modems do not make the Internet a faster network. Instead, they make the connection between the user's PC and the backbone quicker. As the Internet infrastructure is improved accessed content outside of the cable infrastructure will improve. Until then, users will only find the full benefit of Internet access via cable modems through cached content and that content that is served over a private network.
In addition to all of the aforementioned inhibitors, data throughput is bursty. Unlike telco technology, cable modem technology does not support CBR (constant bit rate). Cable modem users are not connected to the backbone at 10 Mbps or 1 Mbps. The data rate is going to bounce up and down during a transfer. For a couple of seconds, a user may be getting 2 Mbps and then suddenly drop to 70 Kbps then jump up to 400Kbps and so on and so on.
The average throughput of this bursty connectivity to the cable headend will depend on the cable modem technology utilized and all of the factors mentioned above. Since all cable plants are different and all activity within a neighborhood node is going to be unique not only in general, but at any given moment, there is absolutely no way to provide a fixed data throughput rate to cable modem service. Testimonials range from users claiming throughputs in excess of 2 Mbps, while others have claimed that their 56k modem provided greater connectivity speeds.
In 99.9% of the cases, cable modem users are getting throughput to the cable headend and to the traditional Internet at speeds greater than that provided by an ISDN connection. A ballpark average (provided reluctantly) for throughput to the Internet would be 500Kbps down and 128Kbps up. For accesses within the cable network, the ballpark average throughput would be 1.5 Mbps downstream and 500Kbps upstream.
While the reference numbers provided may be far below those advertised by a provider, the difference between a 56k or ISDN connection and a cable modem connection at the above mentioned data rates is dramatic. Web pages pop up instantly. Large file downloads are executed in seconds or minutes rather than hours. Streaming audio and video and multi-player gaming is adequately supported. The mean time spent on Internet activities is reduced, allowing the user to do much more in a given time. Despite whether or not the throughput matches what is advertised, for the money, cable modem service is almost always the best value an Internet user can get for a high-speed connectivity to the Internet.
