3 ms·
Similar idea (coded TCP) is patented: http://www.codeontechnologies.com/technology/use-cases/coded-tcp/ http://www.codeontechnologies.com/technology/use-cases/c
by ycmbntrthrwaway 11y ago
Similar idea (coded TCP) is patented:
http://www.codeontechnologies.com/technology/use-cases/coded-tcp/ http://www.codeontechnologies.com/technology/use-cases/coded...
They are selling licenses to Cisco: http://www.codeontechnologies.com/partners/ http://www.codeontechnologies.com/partners/
The idea is simple: XOR random combinations of packets and use gaussian elimination to restore them. Google uses simplest version of it, where they XOR together groups of N packets and send them as N+1 packets, so they can recover one packet if it is lost.
- justicezyx 11y agoThat sounds like network coding
- colanderman 11y agoYa, I don't understand how that's patented. It must be a very specific patent. A few years ago when I first learned of the woes of TCP over lossy links literally the first thought that popped into my head was "why not code N packets into M>N and recover using Gaussian elimination over GF-2"? Such an idea could have passed for non-obvious maybe 50 years ago but it's a pretty basic idea in the 21st century. To be clear, you can trivially apply any technique here: https://en.wikipedia.org/wiki/Erasure_code https://en.wikipedia.org/wiki/Erasure_code across packets in a channel.
- ycmbntrthrwaway 11y agoThe goal of network coding is increased throughput, and it is only possible in multicast case. Authors of CTCP also call it "network coding", but in their case they just decrease delay in the case of loss. Throughput of normal TCP is lower, but only because it reacts to loss by decreasing throughput, so the same throughput can be obtained by using more aggressive congestion control.