Forum Discussion
Connection table entry removed after idle timer reaches tcp keep alive value
Problem: i am doing a telnet to a VIP configured on an LTM and the Connection table entry removed after idle timer reaches tcp keep alive value configured which is 60 seconds and also the i see the idle time counter resetting to zero which is expected My question is why is the connection table entry removed??
Below is LTM Config
ltm virtual testvip { destination 6.6.6.6:9041 ip-protocol tcp mask 255.255.255.255 persist source_addr { Default yes} pool testpool profiles tcp_test snat automap
}
ltm profile tcp tcp_test {app-service none defaults-from tcp-lan-optimized keep-alive-interval 60 }
19 Replies
- Anesh
Cirrostratus
nitass can u help?
- nitass
Employee
why is the connection table entry removed??
is there any FIN or RST? you are running tcpdump when testing, aren't you?
- Anesh
Cirrostratus
i was checking the connection table using show sys connection cs-client-addr all-properties
- Anesh
Cirrostratus
Should i run a tcpdump, what is the filter i need to use?
- nitass
Employee
if you are running 11.2.0 or later, you may try this.
by the way, please make note the time when entry is removed from connection table. so, you can match it in the tcpdump file.
tcpdump -nni 0.0:nnnp -s0 -w /var/tmp/output.pcap host x.x.x.x -v x.x.x.x is client ipsol13637: Capturing internal TMM information with tcpdump
http://support.f5.com/kb/en-us/solutions/public/13000/600/sol13637.html - Anesh
Cirrostratus
i am running 11.1.0 HF9 and the time it gets removed corresponds to the keep alive interval i have set which is for 60secs
- nitass
Employee
i am running 11.1.0 HF9
tcpdump -nni 0.0:nnn -s0 -w /var/tmp/output.pcap '(host x.x.x.x and host 6.6.6.6 and port 9041) or (host a.a.a.a and host b.b.b.b and port ccc)' -v x.x.x.x is client ip a.a.a.a is snat automap ip (floating self ip on server vlan) b.b.b.b is pool member ip ccc is pool member port - Anesh
Cirrostratus
i am seeing a FIN Sent by the LTM VIP
- nitass
Employee
How do i find out from the pcap if the server is sending it first, any specific filter i can apply on the wireshark to see it
you may run tcpdump with FIN and RST filter but i think it is good to capture all and filter in wireshark. anyway, there are some filter example here in case if you are interested.
A tcpdump Tutorial and Primer
http://www.danielmiessler.com/study/tcpdump/in the frames before the LTM VIP sends a FIN, i do see the server sending a RST packet, could this be the cause??
may be. can you find out why serer sends reset?
- Anesh
Cirrostratus
if a RST is sent by the server, why should the VIP send a FIN, shouldn't the VIP also send a RST?
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