070703 / Cost of Bandwidth

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One obvious cost to factor into any online game is the cost of network bandwidth and hosting.

  1. Cost of network bandwidth (dedicated server) is about $0.25/GB/month.

In terms of handling peak bandwidth.

  1. One dedicated server peak bandwidth flows through a 100Mbps ethernet card.
  2. So peak bandwidth is 12.5 MB/s.
  3. Which is 204,800 packets/s of minimum sized UDP packets.
  4. Which is 10K cycles/packet on a 2GHz server.
  5. BOTTOM LINE, one server can handle peak bandwidth.

In terms of average bandwidth.

  1. Average bandwidth has to be well under peak levels (2% to 10%).
  2. Typical starting bandwidth is 640 GB/month (for $150/month).
  3. This is an average of 250 KB/s.
  4. Typical maximum bandwidth for one server is 3840 GB/month (for $775/month).
  5. This is an average of 1503 KB/s.

Given a server centric model (all traffic goes through server), taking in consideration a 1/9 online time factor (players only play 11% of the time), and a full 128 Kbps constant network connection, the maximum bandwidth case could only support 845 players, and would cost about $1/player/month for bandwidth. BOTTOM LINE, server centric model cannot support a large number of high bandwidth connections.

Most current online FPS (first person shooter) games use server centric model with high bandwidth connections, and thus have a very limited number of players per server, which can be seen in the max players/server chart on GameSpy. The FPS genre doesn't fit well with the MMOG (massively multiplayer online game) model, since they are limited usually to 16-64 players interacting at one time. The limitations of central server bandwidth is sure to be a factor in why a majority of MMOGs are RPGs (roll playing games), due to RPGs needing only a very low bandwidth connection to the players.

Atom however is going to have FPS interactivity with MMOG numbers of players, so a mix of P2P (peer to peer) and server centric network models is the only option.