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So to summarise, nobody uses it because nobody uses it? I don't buy it. I think TCP is "good enough" for most cases, so people use it. SCTP is great, but TCP i

So to summarise, nobody uses it because nobody uses it? I don't buy it. I think TCP is "good enough" for most cases, so people use it. SCTP is great, but TCP isn't broken. Worse is better and all that.

deleted 11y ago
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tptacek 11y ago
This writer seems to think the killer problem SCTP solves is end-system level IP multihoming. I think that's actually not a problem that many apps really have. To me, the real promise of SCTP always seemed to be that it was a reliable out-of-order datagram protocol that played nicely with TCP. Essentially: that it killed the need for applications that can't deal with the slowness of in-order delivery in TCP to write their own protocols. I think the big mistake with SCTP was in making it an IP protocol, rather than a protocol that lived underneath UDP.
- teacup50 11y ago
  It's a problem that apps have, but they just shift it onto the user.
  - tptacek 11y ago
    That's a bit hard for me to fathom, because the overwhelming vast majority of users don't have multiple Internet connections, and serverside applications can make use of multiple Internet connections without protocol-level multihoming.
    - signa11 11y ago
      > because the overwhelming vast majority of users don't have multiple Internet connections your shiny iphone/andriod etc. are all multihomed...
      - 0xdeadbeefbabe 11y ago
        So, the problem is not shifted onto the user?
        ay 11y ago
        Correct, it's not. It's shifted on the application developer, who is the "user" of the network stack.
    - ay 11y ago
      Next time you reconnect your SSH session after changing from one WiFi network to another one, consider that this is a degenerate case of multihoming.
    - chetanahuja 11y ago
      ummm.... mobile devices, though not truly multihomed (in the sense of using multiple NIC's simultaneously) approximate multihoming in a time-division sense.
noselasd 11y ago
Well "nobody" is a bit misnomer. It's still widely used in telco networks, transporting control messages to/from your mobile device within the core network, and in interconnects between carriers.
detaro 11y ago
Aren't you basically saying the same thing? TCP was good enough for most cases, so nobody uses it. And anybody who wants to use it can't, because it isn't widely enough supported to be reliable over the public internet. And it isn't widely supported because nobody uses it. MCTCP (which probably is most famous right now for being used by Apple for Siri) is a cool but complex hack on top of TCP to provide multi-homing without confusing middle-boxes. HTTP2/SPDY/QUIC have their own mechanisms to get multiple streams in one connection over TCP/UDP.

deleted 11y ago

[deleted]

tptacek 11y ago

This writer seems to think the killer problem SCTP solves is end-system level IP multihoming. I think that's actually not a problem that many apps really have. To me, the real promise of SCTP always seemed to be that it was a reliable out-of-order datagram protocol that played nicely with TCP. Essentially: that it killed the need for applications that can't deal with the slowness of in-order delivery in TCP to write their own protocols. I think the big mistake with SCTP was in making it an IP protocol, rather than a protocol that lived underneath UDP.

teacup50 11y ago
It's a problem that apps have, but they just shift it onto the user.
- tptacek 11y ago
  That's a bit hard for me to fathom, because the overwhelming vast majority of users don't have multiple Internet connections, and serverside applications can make use of multiple Internet connections without protocol-level multihoming.
  - signa11 11y ago
    > because the overwhelming vast majority of users don't have multiple Internet connections your shiny iphone/andriod etc. are all multihomed...
    - 0xdeadbeefbabe 11y ago
      So, the problem is not shifted onto the user?
      - ay 11y ago
        Correct, it's not. It's shifted on the application developer, who is the "user" of the network stack.
  - ay 11y ago
    Next time you reconnect your SSH session after changing from one WiFi network to another one, consider that this is a degenerate case of multihoming.
  - chetanahuja 11y ago
    ummm.... mobile devices, though not truly multihomed (in the sense of using multiple NIC's simultaneously) approximate multihoming in a time-division sense.

noselasd 11y ago

Well "nobody" is a bit misnomer. It's still widely used in telco networks, transporting control messages to/from your mobile device within the core network, and in interconnects between carriers.

detaro 11y ago

Aren't you basically saying the same thing? TCP was good enough for most cases, so nobody uses it. And anybody who wants to use it can't, because it isn't widely enough supported to be reliable over the public internet. And it isn't widely supported because nobody uses it. MCTCP (which probably is most famous right now for being used by Apple for Siri) is a cool but complex hack on top of TCP to provide multi-homing without confusing middle-boxes. HTTP2/SPDY/QUIC have their own mechanisms to get multiple streams in one connection over TCP/UDP.