def6e7da   
   From: barmar@alum.mit.edu   
      
   In article   
   ,   
    ray  wrote:   
      
   > Dear guru :   
   >     Anyone could tell me ,   
   >   
   > Q1 .How many bytes of Application layer header ?   
   > Data(200 bytes) +AP layer header(??)  + TCP header(20 bytes) + IP   
   > header(20 bytes) + Ethernet (14 bytes) + Pad(4 bytes)   
   > I do not know the AP layer header.   
      
   There's no standard application layer header, it depends on the   
   application protocol.  Many protocols don't even have a header, they're   
   just text streams, such as SMTP or TELNET.   
      
   > Q2: MSG A header len (2bytes) + MSG A(100 bytes)=102 bytes,   
   >        MSG B headre len (2 bytes)+ MSG B(50 bytes) =52 bytes,   
   >        Could I   combine   MSG A+MSG B into one DATA  (154 bytes) ?   
      
   It depends on the protocol.  If it's a datagram protocol, there's often   
   a requirement that each message be in a separate datagram.  If it's a   
   stream protocol, and uses TCP as the transport, there's no way for the   
   application to tell how it was transmitted.   
      
   --   
   Barry Margolin, barmar@alum.mit.edu   
   Arlington, MA   
   *** PLEASE don't copy me on replies, I'll read them in the group ***   
      
   --- SoupGate-Win32 v1.05   
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