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atuls_7180's avatar
atuls_7180
Icon for Nimbostratus rankNimbostratus
Jan 12, 2012

Interpreting time-taken IIS log field in load balanced configuration

We are using BIG-IP LTM to load balance between application servers which are running IIS 7.0. Our system is configured to offload SSL to BIG-IP LTM. Our application servers handle compression. I hav...
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nitass's avatar
nitass
Icon for Employee rankEmployee
Jan 12, 2012
When does BIG-IP ACK the final packet sent by IIS to it? Does it wait for the client to ACK its last packet? for ACK, bigip does ACK after receving the last data from IIS.

172.28.19.253 is client

172.28.19.79 is virtual server

200.200.200.10 is bigip selfip

200.200.200.103 is pool member (IIS)

(a) is ACK from bigip to IIS and (b) is ACK from client to virtual server. 

[root@ve1023:Active] config  tcpdump -nnr /var/tmp/test1.pcap |less
23:06:22.584631 IP 172.28.19.253.54264 > 172.28.19.79.80: S 396640664:396640664(0) win 5840  in slot1/tmm0 lis=
23:06:22.584687 IP 172.28.19.79.80 > 172.28.19.253.54264: S 3228099800:3228099800(0) ack 396640665 win 4380  out slot1/tmm0 lis=bar
23:06:22.587460 IP 172.28.19.253.54264 > 172.28.19.79.80: . ack 1 win 46  in slot1/tmm0 lis=bar
23:06:22.587501 IP 172.28.19.253.54264 > 172.28.19.79.80: P 1:164(163) ack 1 win 46  in slot1/tmm0 lis=bar
23:06:22.588445 IP 200.200.200.10.54264 > 200.200.200.103.80: S 3684513503:3684513503(0) win 4380  out slot1/tmm0 lis=bar
23:06:22.591665 IP 200.200.200.103.80 > 200.200.200.10.54264: S 2947746950:2947746950(0) ack 3684513504 win 64240  in slot1/tmm0 lis=bar
23:06:22.591676 IP 200.200.200.10.54264 > 200.200.200.103.80: . ack 1 win 4380  out slot1/tmm0 lis=bar
23:06:22.591692 IP 200.200.200.10.54264 > 200.200.200.103.80: P 1:164(163) ack 1 win 4380  out slot1/tmm0 lis=bar
...
23:06:22.648476 IP 200.200.200.103.80 > 200.200.200.10.54264: P 168951:169771(820) ack 164 win 64077  in slot1/tmm0 lis=bar
(a) 23:06:22.648481 IP 200.200.200.10.54264 > 200.200.200.103.80: . ack 169771 win 11676  out slot1/tmm0 lis=bar
...
23:06:22.681558 IP 172.28.19.79.80 > 172.28.19.253.54264: P 168575:169771(1196) ack 164 win 4543  out slot1/tmm0 lis=bar
(b) 23:06:22.691678 IP 172.28.19.253.54264 > 172.28.19.79.80: . ack 169771 win 374  in slot1/tmm0 lis=bar
23:06:22.717556 IP 172.28.19.253.54264 > 172.28.19.79.80: F 164:164(0) ack 169771 win 453  in slot1/tmm0 lis=bar
23:06:22.717574 IP 172.28.19.79.80 > 172.28.19.253.54264: . ack 165 win 4543  out slot1/tmm0 lis=bar
23:06:22.717580 IP 200.200.200.10.54264 > 200.200.200.103.80: F 164:164(0) ack 169771 win 11676  out slot1/tmm0 lis=bar
23:06:22.718441 IP 200.200.200.103.80 > 200.200.200.10.54264: . ack 165 win 64077  in slot1/tmm0 lis=bar
23:06:22.718448 IP 200.200.200.103.80 > 200.200.200.10.54264: F 169771:169771(0) ack 165 win 64077  in slot1/tmm0 lis=bar
23:06:22.718456 IP 200.200.200.10.54264 > 200.200.200.103.80: . ack 169772 win 11676  out slot1/tmm0 lis=bar
23:06:22.718459 IP 172.28.19.79.80 > 172.28.19.253.54264: F 169771:169771(0) ack 165 win 4543  out slot1/tmm0 lis=bar
23:06:22.719640 IP 172.28.19.253.54264 > 172.28.19.79.80: . ack 169772 win 453  in slot1/tmm0 lis=bar