[Mainline-Build 2683]: reverse flow hold when repeated syn-fin in loop

[alok kumar]

below is the tcpdump for one complete flow:

10:38:05.935915 IP 1.1.1.3.8001 > 2.2.2.3.ssh: Flags [S], seq 738233535, win 14600, options [mss 1420,sackOK,TS val 21150148 ecr 0,nop,wscale 6], length 0
10:38:05.935951 IP 2.2.2.3.ssh > 1.1.1.3.8001: Flags [S.], seq 4058638348, ack 738233536, win 14480, options [mss 1460,sackOK,TS val 21138954 ecr 21150148,nop,wscale 5], length 0
10:38:05.936190 IP 1.1.1.3.8001 > 2.2.2.3.ssh: Flags [.], ack 1, win 229, options [nop,nop,TS val 21150149 ecr 21138954], length 0
10:38:05.938736 IP 1.1.1.3.8001 > 2.2.2.3.ssh: Flags [P.], seq 1:4, ack 1, win 229, options [nop,nop,TS val 21150149 ecr 21138954], length 3
10:38:05.938752 IP 2.2.2.3.ssh > 1.1.1.3.8001: Flags [.], ack 4, win 453, options [nop,nop,TS val 21138955 ecr 21150149], length 0
10:38:05.943583 IP 2.2.2.3.ssh > 1.1.1.3.8001: Flags [P.], seq 1:40, ack 4, win 453, options [nop,nop,TS val 21138956 ecr 21150149], length 39
10:38:05.943603 IP 2.2.2.3.ssh > 1.1.1.3.8001: Flags [FP.], seq 40:59, ack 4, win 453, options [nop,nop,TS val 21138956 ecr 21150149], length 19
10:38:05.943727 IP 1.1.1.3.8001 > 2.2.2.3.ssh: Flags [.], ack 40, win 229, options [nop,nop,TS val 21150151 ecr 21138956], length 0
10:38:05.943881 IP 1.1.1.3.8001 > 2.2.2.3.ssh: Flags [F.], seq 4, ack 60, win 229, options [nop,nop,TS val 21150151 ecr 21138956], length 0
10:38:05.943896 IP 2.2.2.3.ssh > 1.1.1.3.8001: Flags [.], ack 5, win 453, options [nop,nop,TS val 21138956 ecr 21150151], length 0

when same is repeated in loop, reverse flow is marked hold for long time after few iterations.

root@nodec12:~# flow -l | grep ":22 " -A2 -B2 | grep 8001 -A2 -B2

    32804 2.2.2.3:22 6 (2)
                         1.1.1.3:8001
    (K(nh):32, Action:H, Flags:, TCP:SSr, S(nh):0, Statistics:17/1186 UdpSrcPort 0)
--
--
--

   157328<=>32804 1.1.1.3:8001 6 (1)
                         2.2.2.3:22
    (K(nh):18, Action:F, Flags:, TCP:S, S(nh):18, Statistics:12/888 UdpSrcPort 53744)

Naveen has debugged the issue.

[Naveen N (naveenn)]

Fixed with new index manager changes
https://github.com/Juniper/contrail-controller/commit/8da0a187adcced5a59b2e7233b451530c474b26a