How to find the real IP to which IPVS is routing a virtual IP
- by Wayne Conrad
I'm trying to find a problem server hiding behind a virtual IP (using LVS/ipvs). I've got a test program that sends requests to the virtual IP until it gets the bad response, but how can I tell to which real IP a request to the virtual IP got routed?
On the box doing the virtual IP magic, here's the virtual IP configuration (for the service I care about):
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
...
TCP 10.1.0.254:5025 nq
-> 10.1.0.5:5025 Route 1 0 1
-> 10.1.0.6:5025 Route 1 0 5
-> 10.1.0.7:5025 Route 1 0 2
-> 10.1.0.9:5025 Local 1 0 3
-> 10.1.0.11:5025 Route 1 0 3
...
My client program is sending TCP requests to 10.1.0.254:5025, usually getting a good response but sometimes a bad response. With this few servers, I could send my request to each server in turn until I discover the culprit, but I wonder if that technique will scale as we add servers. What means exist for me to find out where requests got routed?
Kernel: Linux 2.6.32
OS: Debian testing (whatever that's called these days).
ipvsadm is version 1.25, compiled with ipvs v1.2.1
