Greetings Foundry-NSP, We have an internal ServerIron ADX 12.3 sandwiched between a couple linux servers, one being the client of the other.
The client reuses TCP source-ports as expected. tcp_tw_re(use|cycle) is disabled. I have observed however, that when my linux client reuses the source-port of a recently closed (8-12 seconds old) TCP connection, the ServerIron does not acknowledge the SYN. The linux client will retransmit using the same src-port after 3 seconds, and again after 6 seconds (9 seconds total) if necessary. I believe the "3 second retransmission" and subsequent doubling is defined in RFC1122, but the 8-12 second window is just an observation. My question(s): How do I configure the ServerIron to either accept/acknowledge this TCP flow? Or, how do I configure the ServerIron to send a NACK or RST to the client, so that we can abort the 3/6/12 second retransmission timers? Am I naive to expect the ServerIron session entry (or whatever) to expire faster than the 8-12 seconds (<< 2*MSL)? Thank you, lyle Here's a sample flow where 10.0.0.3 is the source/client, and 10.0.210.92 is the virtual-server/ServerIron. The 3-second and 6-second retransmissions can be found at 17:29:43 and 17:29:49. The ServerIron (10.0.210.92) ignores the first two SYNs, then finally ACKs the third (the second retransmission): 17:29:36.738326 IP 10.0.210.92.80 > 10.0.0.3.44368: . ack 2076 win 9612 17:29:36.738330 IP 10.0.0.3.44368 > 10.0.210.92.80: R 3731308505:3731308505(0) win 0 17:29:40.831336 IP 10.0.0.3.44368 > 10.0.210.92.80: S 3736246299:3736246299(0) win 17920 17:29:43.830840 IP 10.0.0.3.44368 > 10.0.210.92.80: S 3736246299:3736246299(0) win 17920 17:29:49.830005 IP 10.0.0.3.44368 > 10.0.210.92.80: S 3736246299:3736246299(0) win 17920 17:29:49.830081 IP 10.0.210.92.80 > 10.0.0.3.44368: S 1833587:1833587(0) ack 3736246300 win 8000 17:29:49.830098 IP 10.0.0.3.44368 > 10.0.210.92.80: . ack 1 win 17920 17:29:49.830190 IP 10.0.0.3.44368 > 10.0.210.92.80: P 1:159(158) ack 1 win 17920 17:29:49.830680 IP 10.0.210.92.80 > 10.0.0.3.44368: . ack 159 win 6432 _______________________________________________ foundry-nsp mailing list [email protected] http://puck.nether.net/mailman/listinfo/foundry-nsp
