Documentation: Network Monitoring
source:http://www.brendangregg.com/Perf/network.html

The following is a guide to monitoring network interfaces and the network from the Solaris operating system.
Note: This document is not written by Sun.
Brendan Gregg, 09-Oct-2005, version 0.70.

Is your network busy?

The network often gets blamed when things are performing poorly, and perhaps this is correct - your network interfaces may be running at 100% utilisation.

What command will tell you how busy the network interface is? Many sysadmins suggest using netstat -i to find out,

$ netstat -i 1
    input   hme0      output           input  (Total)    output
packets errs  packets errs  colls  packets errs  packets errs  colls
70820498 6     73415337 0     0      113173825 6     115768664 0     0   
242     0     149     0     0      246     0     153     0     0
1068    0     552     0     0      1075    0     559     0     0
[...]