Forum Discussion
gdoyle
Cirrostratus
CirrostratusTCP Health Check.
All, I have a customer who mentioned that they took a server down for maintenance, but were still receiving customer traffic. This server sits in a pool tied to a VIP and is load balanced wit...
TCP monitor will try a TCP handshake, if that is successful, marks pool member up.
If you use the default TCP monitor, the alias address field is *, that means it will get the port from the pool member.
So, if pool member is 192.168.1.1:639, it will try a TCP handshake with 192.168.1.1 on port 639.
In the case you described, if the application itself was down, but the server still had the port TCP/639 open, the monitor will still mark the server up.
You need an application layer monitor.
The system has a built in LDAP monitor, so you should use that.
gdoyleCirrostratus
CirrostratusThanks for the confirmation, Leonardo, and I concur about the use of an application monitor, unfortunately I did not architect their solution. I think the main cause in this case was that they decided to rely upon the health monitor to mark the pool as down while they did planned maintenance.