TCP push option

Shaw Carruthers (shaw@shawc.demon.co.uk)
Fri, 22 May 1998 15:57:40 +0100 (GMT+0100)

I am investigating why I am getting poor ftp throughput. As the following
Tcpdump log extract shows when I receive a p flag there is a 20 second
pause.

14:13:17.829699 158.152.146.90.1046 > 194.159.255.135.20: . ack 60833 win 16060 (DF) [tos 0x8]
14:13:17.839699 194.159.255.135.20 > 158.152.146.90.1046: . 60833:62293(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:18.339699 158.152.146.90.1046 > 194.159.255.135.20: . ack 62293 win 16060 (DF) [tos 0x8]
14:13:18.359699 194.159.255.135.20 > 158.152.146.90.1046: . 62293:63753(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:18.469699 194.159.255.135.20 > 158.152.146.90.1046: P 63753:64077(324) ack 1 win 8760 (DF) [tos 0x8]
14:13:18.989699 194.159.255.135.20 > 158.152.146.90.1046: . 64077:65537(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:19.509699 194.159.255.135.20 > 158.152.146.90.1046: . 65537:66997(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:20.019699 194.159.255.135.20 > 158.152.146.90.1046: . 66997:68457(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:20.529699 194..159.255.135.20 > 158.152.146.90.1046: . 68457:69917(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:21.039699 194.159.255.135.20 > 158.152.146.90.1046: . 69917:71377(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:21.559699 194.159.255.135.20 > 158.152.146.90.1046: . 71377:72837(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:22.079699 194.159.255.135.20 > 158.152.146.90.1046: . 72837:74297(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:22.579699 194.159.255.135.20 > 158.152.146.90.1046: . 74297:75757(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:23.399699 194.159.255.135.20 > 158.152.146.90.1046: . 62293:63753(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:23.899699 158.152.146.90.1046 > 194.159.255.135.20: . ack 63753 win 16060 (DF) [tos 0x8]

14:13:42.289699 194.159.255.135.20 > 158.152.146.90.1046: . 63753:65213(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:42.799699 158.152.146.90.1046 > 194.159.255.135.20: . ack 65213 win 16060 (DF) [tos 0x8]
14:13:43.459699 194.159.255.135.20 > 158.152.146.90.1046: . 65213:66673(1460) ack 1 win 8760 (DF) [tos 0x8]
14:13:43.969699 158.152.146.90.1046 > 194.159.255.135.20: . ack 66673 win 16060 (DF) [tos 0x8]

Can some TCP guru advise what is going wrong here?

I am using ncftp-2.3.0 over ppp-2.3.5 on kernel 2.1.103

--
Shaw Carruthers - shaw@shawc.demon.co.uk
London SW14 7JW UK
This is not a sig( with homage to Magritte).
  




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