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Data dashboard: Aspera’s user interface lets a user control data-transfer rates and shows transfer times and real-time network information.
Aspera
Unlike TCP, FASP does not wait for confirmation of receipt, but simply assumes that all packets have arrived, says Simon Hudson of Cloud2, a provider of cloud-computing services in East Yorkshire, U.K., and an early adopter of FASP. Under this protocol, only packets that are confirmed to have been dropped are re-sent. "And instead of sending lots of small packets, it sends fewer large packets," Hudson says. The result is that the available bandwidth is used more efficiently--more data gets through, and it gets there faster.
Another issue is traffic monitoring, says Anna Liu, a cloud-computing researcher at the University of New South Wales in Sydney, Australia. "In cloud computing, the challenge is the unpredictable nature of the public network," she says. "You can't control what else is happening on the network due to other people's activities."
FASP handles this unpredictability by monitoring all network traffic and altering the size of packets and the rate and order in which they are sent, according to available bandwidth and other traffic issues. This way, the data flow can be regulated, ensuring that FASP data gets through without saturating the network. This also means it becomes possible to guarantee file-transfer times, says Munson. When transferring data over a 100 Mbps connection, Munson says, "FASP will achieve about 95 Mbps or better."
Since Amazon is such a big player in cloud computing, its adoption of FASP could broaden the appeal of the technology, says Trigg. "It's the 800-pound gorilla in the market," he says. "If you improve the network connection, you lower the hurdle and allow more people to use it."
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Would this be applicable to torrenting? If everyone used this protocol could it increase upload and download speeds?
The description of TCP in this article is misleading. While it is true that you can make TCP behave as described, that is by no means the only option. TCP provides for negotiable packet size, a negotiable size for a sliding window of outstanding (unacknowledged) packets, and also provides for selective acknowledgment of packets. This means that TCP can efficiently utilize a large bandwidth with significant latency and packet loss. It pipelines packet transmissions and only retransmits lost packets. There are issues with TCP that might require a different protocol (usually based on UDP), but they don't appear to be described in the article.
While it is true that TCP can be implemented to achieve very high transfer rates, such implementations are not conformant to the standard and are usually deemed bad network citizens. The reason has to do with congestion control.
TCP has a behavior built into it called "slow start," which causes TCP senders to stop and wait for each one or two packets to be acknowledged when it starts up or, after stabilizing, it detects a missing acknowledgment. After dropping into slow start, the sender will rapidly increase the amount of data sent before requiring an acknowledgment, then attempt to stabilize the amount of data sent at a size appropriate for avoiding congestion. (I'm oversimplifying this a bit...) The net result is that TCP is intentionally very sensitive to packet loss, which is usually a very good indication of network congestion.
Slow start was added to TCP to prevent it from congesting intervening network routers, and then continuing to overload them until they underwent congestive collapse. In essence, slow start causes any individual connection to behave suboptimally, but it tends to make transfer over the internet as a whole, with tens of thousands of TCP connections, as efficient as possible.
Congestion control is very, very tricky. I wonder if FASP has been engineered adequately to avoid congestion problems. If not, you'll see a lot of pushback from tier 1 and 2 ISPs and FASP will go the way of the other twenty or thirty attempts to engineer something better than TCP.
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This document is part of the “How-To Guide for Most Common Measurements” centralized resource portal. This tutorial provides a detailed guide for measurement and device considerations to take temperature measurements using thermocouples. Get an introduction to thermocouples, which are inexpensive sensing devices widely used with PC-based data acquisition systems. Also review some specific thermocouple examples and learn how thermocouples work and ways to integrate them into a data acquisition measurement system.
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andy_mydur
6 Comments
cloud computing
With the ever increasing data uploading & transmission "cloud computing " will play an decesive role in the Internet world.
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