Pong: A Flexible Network Services Monitoring System

In distributed computing environments it is important to determine not only whether individual critical machines are up or down, but also whether the individual services they offer are available. Our site was using a network monitoring package which used ICMP ECHO packets to determine when individual network components were unavailable. We found that there were many occasions where a server would reply to the ICMP ECHO, but would still not be providing the services it should be providing. We needed a tool which would let us monitor high level services such as AFS or NFS file service. This paper will describe a tool called pong which was developed to meet these needs. Pong is a highly configurable monitoring tool which "pings'' individual services at predefined intervals and executes appropriate actions when the state of that service changes. We use pong to monitor three or more services on each of 110 servers.