TCP not being proactive about recoving lost packets

[Peter Jeremy]

I am trying to ftp mysql-5.1.25-rc.tar.gz from ftp.easynet.be and
noticed that progress appeared to have ceased and the ETA increasing.
Looking at a tcpdump of the FTP data socket showed:

10:31:17.273106 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 4054413516:4054414976(1460) ack 635248902 win 92
10:31:17.372968 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 1460 win 28692
10:31:17.709750 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 118260:119720(1460) ack 1 win 92
10:31:17.709807 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 1460 win 28692
10:31:17.713318 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 119720:121180(1460) ack 1 win 92
10:31:17.713368 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 1460 win 28692
10:33:17.717063 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 1460:2920(1460) ack 1 win 92
10:33:17.816684 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 2920 win 28692
10:33:18.126643 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 121180:122640(1460) ack 1 win 92
10:33:18.126666 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 2920 win 28692
10:33:18.128224 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 122640:124100(1460) ack 1 win 92
10:33:18.128239 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 2920 win 28692
10:35:18.130354 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 2920:4380(1460) ack 1 win 92
10:35:18.229382 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 4380 win 28692
10:35:18.549832 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 124100:125560(1460) ack 1 win 92
10:35:18.549855 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 4380 win 28692
10:35:18.552361 IP minx.ftp.be.easynet.net.57796 > myhost.mydomain.xxx.yyy.56432: . 125560:127020(1460) ack 1 win 92
10:35:18.552376 IP myhost.mydomain.xxx.yyy.56432 > minx.ftp.be.easynet.net.57796: . ack 4380 win 28692

The FTP server resends an old packet then 2 new packets.  FreeBSD ACKs each
packet with the next packet it wants.  Then there's a 2 minute timeout before
the FTP server responds.  This ahs been going on for about 45 minutes now.

The client is running 7-STABLE from mid-May.  Shouldn't it continue to
regularly send ACKs where it knows there is outstanding data?

-- 
Peter Jeremy
Please excuse any delays as the result of my ISP's inability to implement
an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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