Forum Discussion
Piotr_Lewandows
Altostratus
AltostratusTCP close vs active close and timers
Hi,
I already read few great post here as well as some articles but I am still not sure how things are working on BIG-IP.
First of all I wonder if there is a way to monitor connection states via ...
dragonflymr
Cirrostratus
CirrostratusJust another question that popped up after some more tests.
Client is closing connection with BIG-IP, sequence of packets is (sequence number and ack i parenthesis):
- C (115, 432) -> BIG-IP - FIN-ACK (ACK is for last packet send by BIG-IP - HTTP reply)
- BIG-IP (432, 115) -> C - FIN-ACK (ACK for last packet received from client)
- C (116, 433) -> BIG-IP - ACK - for FIN packet from BIG-IP
- BIG-IP (433, 116) -> C - ACK to client FIN
Is above indication that it is active close - both sides are closing connection at the same time?
Is that default behavior for BIG-IP or it can be changed so standard close is performed?
Another strange issue noticed - when Time Wait Recycle is disabled.
I expected that BIG-IP will send RST when another connection from same IP:port is comming when connection on BIG-IP is in TIME-WAIT state.
It was not the case. Instead BIG-IP replied with ACK but using ack number send in last packet of previus connection. As an result client is sending RST and then retrying with SYN (again ACK and RST until client maximum SYN retransmission is reached or connection on BIG-IP is removed after Time Wait expires.
Piotr