[MUD-Dev] Transport layer (UDP vs TCP)

[Ben Greear]

On Wed, 18 Mar 1998, Jon Leonard wrote:

> > I was mostly hoping that someone had a good 'working maximum' that they
> > had used with success.  However, most MUD's would deal wrather poorly
> > with a lossy protocol, so there may not be much experience with UDP
> > in the mud community....
> 
> In many ways, an easier question.  Most of the networks you need to worry
> about are ethernet or can handle ethernet-sized packets.  So your maximum
> packet size should be 1500 minus a margin for IP headers.  If you can fit
> into 512 bytes, that'd be fine.
> 
> You'll lose more clients due to firewalls that block UDP than you will to
> strange networks.  Be prepared for re-assembled packets, though -- the
> last hop may be a noisy PPP session that fragments, for example.

Well, I plan on having a tcp as well as a udp connection running
simultaneously, so if one won't work, I can just shift the traffic to
the other.  Actually, could shift UDP to TCP, not going to try to
go the other way.

If your packets can be fragmented at the last step (I'm assuming most
players will be using PPP over a modem) then it could become very nasty
as far as reading a complete packet in no?  Does the UDP somehow keep
you from reading half of a packet (the other half of which has been lost
forever?)

For instance, I send a 512 byte UDP packet.  Can the receiver ever just
receive the first 256 bytes or so?  Surely not, as this would make it
basically impossible to code anything without writing another layer on
top of it...

Yeesh, I need thicker books!!

Ben

Ben Greear (greear at cyberhighway.net)  http://www.primenet.com/~greear 
Author of ScryMUD:  mud.primenet.com 4444
http://www.primenet.com/~greear/ScryMUD/scry.html