Sega [email protected]

Following the new leads and information gathered recently, it seems that Sega’s proprietary networking system “SNAP” was not (primarily atleast) used for hosting Dreamcast games, and was likely to¬†only be used for the PS2 and GC (although support for the Xbox was probably there too).

However, as many of you probably know, a similar system called “Kage” was created earlier in the Dreamcast’s lifespan and provided hosting for many of Sega’s 1st and 2nd party titles, like Alien Front Online, Outtrigger, and so on.

Kage provided developers with a generic set of servers that could be used for just about any type of game and consisted of multiple types of servers, ranging from bootstrap servers for the initial handshake upon connecting, lobby/gameroom servers, status servers and game servers, and (client code) was platform independent (just like Snap). Multiple versions of the Kage servers was created.

However, key differences between the two is that while Kage is a more traditional approach of a unified server system using TCP, UDP and HTTP, Snap also used a proprietary protocol on top of UDP called rUDP (reliable UDP) and was a more advanced approach trying to provide features such as QoS and scalability and because of that was probably a very attractive server model for Nokias mobile gaming division.

Kage seems to have been created sometime in 1999, while Snap (atleast the SDK, might have been used internally before that) was created in 2002.

Example of scalability with Snap:


Example of debugging symbols found for Snap games (PS2):

While the authentication etc is done by TCP, game data is sent using UDP and rUDP and is clearly different from Kage in this manner, although Kage might have been the precursor to what later became Snap.


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  1. Partially related/unrelated : Is there any chance of seeing the Japanese matching service games functioning again?

    Unrelated : Hows about an update?

    • Dan: We have looked into the Japanese games which primarily uses the KDDI system, which is an old pre-TCP service using telephone switching technology to match up players. While some games may be possible to get back through other means, most of them will not be back as the work required far exceed those that use TCP/UDP for their connections.
      Chu-Chu Rocket was the first online multiplayer title for the Dreamcast using TCP. Games before that is using a much older technology which basically would be impossible to use outside of Japan because of the infrastructure required. This is why KDDI was never used outside of Japan.

      There are however some games which appears to not use the KDDI system, in particular the Aero Dancing series (one title even supports the broadband adapter).

      • Hey Petter, The people over at Outbreak Server have KDDI emulation for Resident Evil Outbreak, I’m curious about how relevant their emulation of KDDI would be to Dreamcast games, I’m guessing the KDDI service for the PS2 and the Dreamcast are very different?

        • That would be interesting. If it turns out to be relevant to dc ; MvC2 & Street Fighter 2 = Yes

        • We are looking into this with the obsrv guys. They have a server emulator for the KDDI system used for PS2 games and are willing to check out compatibility with the Dreamcast.

          However, many Dreamcast games used the Dwango system aswell as the KDDI system, which is what makes it difficult because Dwango was basically a telephone switching board technology. The PS2 games did not use this.

          • Interesting stuff, the telephone switching would require real world hardware to do wouldn’t it? or is it something that could be achieved just with software alone?

  2. From what we gathered, Dwango was a hardware based system.

  3. @Aoeu204 With enough research, testing and coding skill you can pretty much do anything. Though to find out what data was transferred you’d probably need the hardware or know enough about it to make your own at some point

  4. itsstillthinking1999

    so from what i got this is that you can more or less remake the sega network and bring back anything on snap like for example the 2k games?

  5. itstillthinking1999

    hey petter i hate to pester but im still curios about my previous question? thanks

    • Like he said in this post most of the games used kage, a primitive version of what became snap. By looking at snap you can get an understanding probably of how it works. But a reverse engineering of kage is probably required to bring back the 2k games and others. This is only speculation on my part though

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