t-delegated.example.com> 25fcb672   
   From: barmar@alum.mit.edu   
      
   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?   
      
   UDP is rarely used for stateful protocols, it's mostly for idempotent   
   request/response protocols (e.g. DNS).  The only counterexample I can   
   think of off the top of my head is TFTP, and it's rarely used across the   
   Internet.   
      
   What "relevant" protocols are you thinking of?   
      
   --   
   Barry Margolin, barmar@alum.mit.edu   
   Arlington, MA   
   *** PLEASE don't copy me on replies, I'll read them in the group ***   
      
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