More problems Short transfers are hard on TCP Stuck in slow start Loss recovery is poor when windows are small Lots of extra connections Increases server state/processing Server also forced to keep TIME WAIT connection state Things to think about Why must server keep these? Tends to be an order of magnitude greater than of active connections, why? Lecture19:2006-11-02
Lecture 19: 2006-11-02 16 More Problems • Short transfers are hard on TCP • Stuck in slow start • Loss recovery is poor when windows are small • Lots of extra connections • Increases server state/processing • Server also forced to keep TIME_WAIT connection state -- Things to think about -- • Why must server keep these? • Tends to be an order of magnitude greater than # of active connections, why?
Persistent Connection Solution(review) Multiplex multiple transfers onto one TCP connection How to identify requests/responses Delimiter> Server must examine response for delimiter string Content-length and delimiter >must know size of transfer in advance Block-based transmission> send in multiple length delimited blocks Store-and-forward wait for entire response and then use content-length Solution use existing methods and close connection otherwise Lecture19:2006-11-02
Lecture 19: 2006-11-02 17 Persistent Connection Solution (review) • Multiplex multiple transfers onto one TCP connection • How to identify requests/responses • Delimiter → Server must examine response for delimiter string • Content-length and delimiter → Must know size of transfer in advance • Block-based transmission → send in multiple length delimited blocks • Store-and-forward → wait for entire response and then use content-length • Solution → use existing methods and close connection otherwise