Form: Memo
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Can someone explain pipelining and persistent connection benefits of HTTP
1.1 to me?
I have set up a simple spreadsheet to analyse this and get contradictory
results.
I have one column which is a single persistent TCP connection to transfer
1MByte, it takes 20 RTTs as can be seen in second column.
I then have four parallel TCPs each transferring 130.5 kBytes taking 8 RTTs.
I then consider 1 RTT for FIN and 3 RTTs for 3way handshake start. Four
more TCPs then start and transfer 130.5 kBytes each in 8 RTTs. The total
for 8 TCPs is 1.04448 MBytes and the single TCP total is 1.048064 MBytes.
However the 8 TCPs finish before the single TCP. How then is it preferable
to pipeline a single TCP rather than transmit multiple parallel TCPs such as
HTTP 1.0 does?
I note that this example is simple, and does not consider the 3-way initial
startup as it is common to all the TCP carriers starting at RTT#1.
Any advice would be most welcome.
Thanks
Matt
sum 1,048,064 130,560 130,560 130,560 130,560 130,560 130,560 130,560 130,560
130,560 130,560 1,044,480
RTT P+p TCP#1 TCP#2 TCP#3 TCP#4 TCP#5 TCP#6 TCP#7 TCP#8
1 512 512 512 512 512
2 1,024 1,024 1,024 1,024 1,024
3 2,048 2,048 2,048 2,048 2,048
4 4,096 4,096 4,096 4,096 4,096
5 8,192 8,192 8,192 8,192 8,192
6 16,384 16,384 16,384 16,384 16,384
7 32,768 32,768 32,768 32,768 32,768
8 65,536 65,536 65,536 65,536 65,536
9 65,536 0 0 0 0 FIN
10 65,536 0 0 0 0 3
11 65,536 0 0 0 0 way
12 65,536 0 0 0 0 start
13 65,536 0 0 0 0 512 512 512 512
14 65,536 0 0 0 0 1,024 1,024 1,024 1,024
15 65,536 0 0 0 0 2,048 2,048 2,048 2,048
16 65,536 0 0 0 0 4,096 4,096 4,096 4,096
17 65,536 0 0 0 0 8,192 8,192 8,192 8,192
18 65,536 0 0 0 0 16,384 16,384 16,384 16,384
19 65,536 0 0 0 0 32,768 32,768 32,768 32,768
20 65,536 0 0 0 0 65,536 65,536 65,536 65,536
20 65,536 0 0 0 0 0 0 0 0 FIN
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