4 ms·

>TCP, the foundational protocol of the Internet, was never designed for a mobile environment. Amusingly, this is actually not true. TCP was originally develope

by catern 8y ago

>TCP, the foundational protocol of the Internet, was never designed for a mobile environment. Amusingly, this is actually not true. TCP was originally developed to run on an inter-network over two networks: the ARPANET which has the reliability characteristics of a "traditional" network, and an extremely mobile network with lots of packet loss: ship-to-ship packet radio. TCP today seems very poorly suited for the mobile environment, but it was in fact originally designed for mobile.

eridius 8y ago
My interpretation of “not designed for mobile” is mobile devices, not mobile network. In particular, TCP is not designed for a scenario where the device keeps leaving old networks and joining new ones, or where a device routinely has 2 network interfaces where one has better performance than the other but which one is better changes frequently.
- catern 8y ago
  Ships, as mobile devices, frequently entered and left packet radio range with each other, or might have multiple other ships in range and have to select which ship to send their packets to.
  - eridius 8y ago
    That would be equivalent to the server going offline and back online, as opposed to the route constantly changing.
    - catern 8y ago
      We're talking about a packet-switched network. The other ships aren't your destination - some server on land is your destination.
- topranks 8y ago
  Multipath-TCP is designed for precisely that.
  - eridius 8y ago
    I may be wrong but isn't Multipath TCP pretty darn new and rarely used? At least on iOS you have to explicitly opt into it, either using the new Network framework for raw networking or a special configuration for URLSession, and also requires an entitlement to even do (no idea why). AFAIK the only Multipath TCP that my iPhone regularly actually uses is Siri. Which is to say, it still feels largely experimental.
    - topranks 8y ago
      You're absolutely correct, it's new, not in mainline Linux kernel yet etc. I just mentioned it as it's a cool project and in time will help address some of the limitations you mention.
cogman10 8y ago
In fact, I'd argue that it is a good fit even today. What wasn't designed for mobile is the Http protocol. HTTP2 solves most of the problems with mobile without changing out TCP. QUIC provides a few benefits, but by and large not many.
- kristofferR 8y ago
  BTW, HTTP3 is actually mostly QUIC (or rather "HTTP-over-QUIC"). https://en.wikipedia.org/wiki/HTTP/3 https://en.wikipedia.org/wiki/HTTP/3

by catern 8y ago

eridius 8y ago

My interpretation of “not designed for mobile” is mobile devices, not mobile network. In particular, TCP is not designed for a scenario where the device keeps leaving old networks and joining new ones, or where a device routinely has 2 network interfaces where one has better performance than the other but which one is better changes frequently.

catern 8y ago
Ships, as mobile devices, frequently entered and left packet radio range with each other, or might have multiple other ships in range and have to select which ship to send their packets to.
- eridius 8y ago
  That would be equivalent to the server going offline and back online, as opposed to the route constantly changing.
  - catern 8y ago
    We're talking about a packet-switched network. The other ships aren't your destination - some server on land is your destination.
topranks 8y ago
Multipath-TCP is designed for precisely that.
- eridius 8y ago
  I may be wrong but isn't Multipath TCP pretty darn new and rarely used? At least on iOS you have to explicitly opt into it, either using the new Network framework for raw networking or a special configuration for URLSession, and also requires an entitlement to even do (no idea why). AFAIK the only Multipath TCP that my iPhone regularly actually uses is Siri. Which is to say, it still feels largely experimental.
  - topranks 8y ago
    You're absolutely correct, it's new, not in mainline Linux kernel yet etc. I just mentioned it as it's a cool project and in time will help address some of the limitations you mention.

cogman10 8y ago

In fact, I'd argue that it is a good fit even today. What wasn't designed for mobile is the Http protocol. HTTP2 solves most of the problems with mobile without changing out TCP. QUIC provides a few benefits, but by and large not many.

kristofferR 8y ago
BTW, HTTP3 is actually mostly QUIC (or rather "HTTP-over-QUIC"). https://en.wikipedia.org/wiki/HTTP/3 https://en.wikipedia.org/wiki/HTTP/3