TFTP .VS. FTP PERFORMANCE

ITEM: RTA000053031

QUESTION:                                                                       
I noticed when transferring identical files ftp is much faster than             
tftp why? Is there a way to change this?                                        
                                                                                
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The TFTP uses UDP. And UDP should be faster than TCP since UDP has              
no windowing and no acknowledgment and hence data transfer can be as            
fast as possible. BUT the TFTP itself has to acknowledge each packet            
and that slows it down. For FTP, TCP insures data integrity. For TFTP           
it has do to that itself. Here is the overview of TFTP protocol from            
RFC783 (TFTP).                                                                  
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Overview of the Protocol                                                        
  Any transfer begins with a request to read or write a file, which also       
serves  to  request a connection.  If the server grants the request, the        
connection is opened and the file is sent in fixed length blocks of  512        
bytes.    Each  data  packet  contains  one  block  of data, and must be        
acknowledged by an acknowledgment packet before the next packet  can  be        
sent.    A  data  packet of less than 512 bytes signals termination of a        
transfer.  If a packet gets lost in the network, the intended  recipient        
will timeout and may retransmit his last packet (which may be data or an        
acknowledgment),   thus  causing  the  sender  of  the  lost  packet  to        
retransmit that lost packet.  The sender has to keep just one packet  on        
hand  for  retransmission, since the lock step acknowledgment guarantees        
that all older packets have been received.  Notice  that  both  machines        
involved  in a transfer are considered senders and receivers.  One sends        
data and receives acknowledgments, the other sends  acknowledgments  and        
receives data.                                                                  
                                                                               
There is no means of changing this.                                             
                                                                                
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This item was created from library item Q676735      BRXVX                      
                                                                                
Additional search words:                                                        
.VS BRXVX COMMUNICATIO DEC94 FTP IX MEASURE OZNEW PERFORMANCE                   
RISCSYSTEM RISCTCP SOFTWARE TCPIP TFTP TUNE                                     
                                                                                
                                                                                
                                                                                
                                                                                
                                                                               



WWQA: ITEM: RTA000053031 ITEM: RTA000053031

Dated: 04/1996 Category: RISCTCP

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