To display network connections and various network interface statistics – netstat is a handy command – line based tool.
Why is it useful for the DBA ?
1) Execute netstat –an to view all active connections (TCP and UDP ports) on a server. The DBA has a quick overview of network activity.
2) Tuning networks requires good quality analysis applied to accurate statictics. High Utilisation and retransmissions are common causes of network related performance issues. nestat is basic in comparison to other sniffer tools – but can assist in the process.
3) netstat will display copious information. Most of it not specific enough for troubleshooting. Fortunately nestat has some parameters to narrow the information.
4) nestat –p TCP displays all the TCP connections
5) netstat –s displays useful statistics such as : failed connection attempts , segments retransmitted . Combined with interval , such as netstat –s 5 will redisplay every 5 seconds
In another post . I’ll outline some methods of troubleshooting network related performance issues