Gea-Suan_Lin_34
Jan 05, 2010Nimbostratus
Packet lost when loading
Hello,
We have two F5 BIG-IP LTM 6400 with 9.4.7 HF2, running with Active/Standby mode. I setup snmp trap, and copy these log to IRC, to let our management team understand what's happen easily.
There are lots of monitor DOWN & UP msgs about one year. But because it's quite quick to UP again, and usually we have 3+ servers in one pool, this is not issue.
Recently, because the site grow, DOWN/UP is quote annoyed, I want to find out the problem and fix it. So I've tried serveral way to diagnose.
I tried to run tcpdump on both web server and F5 itself, and I found there is packet lost, which causes monitor DOWN:
https://gist.github.com/6f573f746c2eed533e65
As you can see, after F5 send first SYN packet, webapi-1's first reply (SYN+ACK) didn't be received by F5. And then both side tried to resend packet, which causes issue.
I also tried to ping (with interval 0.01 sec) and get:
10000 packets transmitted, 9995 packets received, 0.1% packet loss
round-trip min/avg/max/stddev = 0.082/0.235/8.674/0.182 ms
At the same time, I also ping the standby one, which has no packet lost:
10000 packets transmitted, 10000 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.079/0.155/0.666/0.040 ms
Any possible cause ? I've seen some discussion in http://devcentral.f5.com/Default.aspx?tabid=53&view=topic&postid=34302 but this seems not same issue.