From: grahn+nntp@snipabacken.se   
      
   On Mon, 2010-09-13, Morten Reistad wrote:   
   > In article ,   
   > Jorgen Grahn   wrote:   
   >>On Thu, 2010-09-09, glen herrmannsfeldt wrote:   
   >>> In comp.dcom.lans.ethernet Jorgen Grahn  wrote:   
   >>> (snip)   
   >>>   
   >>>> UDP-based protocols keep state too, and are just as picky about where   
   >>>> the datagram came from as TCP. You cannot expect every datagram to   
   >>>> contain full context, so the application protocol uses the source   
   >>>> address:port (and maybe destination too) as a key to lookup state for   
   >>>> the "conversation".   
   >>>   
   >>> Some UDP protocols are picky, but most aren't.  TCP identifies   
   >>> a connection by the quad   
   >>> source-address:source-port:destination-address:destination-port.   
   >>>   
   >>> Many UDP protcols/implementations will accept anything coming   
   >>> into the appropriate port.   
   >>   
   >>I can imagine that applying to DNS and maybe old-fashioned NFS, but do   
   >>any /relevant/ protocols do that?  Let's say those that aren't (cannot   
   >>be) stateless?   
   >   
   > All the UDP-based realtime media protocols do this when implemented   
   > to support this NAT-mode. SIP, RTP/RTCP, IAX, etc   
   >   
   > So do all the tunnel protocols, so people like us can have our own   
   > addressed network on top of the Internet infrastructure, no matter now   
   > much NAT stuff the underlying routers deal with.   
      
   Uh, *which* NAT mode are we talking about, here? I was under the   
   impression that we were discussing a scenario where you could send a   
   number of packets from A to B, and B would see source address C on   
   some of them and D on others, depending which path they took.   
      
   I hope no NAT works like that.   
      
   >>I suppose a protocol could include a session identifier in every   
   >>message, but why do that when the source address (before Skybuck's   
   >>change) provides exactly that, for free?  It also seems like an open   
   >>invitation to DoS attacks.   
   >   
   > RTP, anyone?   
   >   
   > Or IPv6 flow labels inside IPv4 protocol 41?   
   >   
   > Or, even, MPLS?   
      
   I don't understand what you're saying here. Am I supposed to?   
      
   /Jorgen   
      
   --   
     // Jorgen Grahn    O  o   .   
      
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