netstat
netstat
The netstat tool gives statistics on the network subsystem. It can be used to analyze many aspects of the network subsystem, two of which are the TCP/IP kernel module and the interface bandwidth. An overview of both uses follow.
netstat -I hme0 10
These netstat options are used to analyze interface bandwidth. The upper bound (max) of the current throughput can be calculated from the output. The upper bound is reported because the netstat output reports the metric of packets, which don't necessarily have to be their maximum size. The upper bound of the bandwidth can be calculated using the following equation:
Bandwidth Used = (Total number of Packets) / (Polling Interval (10) ) ) * MTU (1500 default).
The current MTU for an interface can be found with: ifconfig
netstat |
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#netstat |
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input | hme0 |
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| input | (Total) | output |
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packets errs | packets errs | colls | packets errs | packets errs | colls | ||||||
122004816 | 272 |
| 159722061 0 | 0 | 348585818 2582 | 440541305 2 | 2 | ||||
0 | 0 |
| 0 | 0 | 0 | 84144 | 0 | 107695 | 0 | 0 | |
0 | 0 |
| 0 | 0 | 0 | 96144 | 0 | 123734 | 0 | 0 | |
0 | 0 |
| 0 | 0 | 0 | 89373 | 0 | 114906 | 0 | 0 | |
0 | 0 |
| 0 | 0 | 0 | 84568 | 0 | 108759 | 0 | 0 | |
0 | 0 |
| 0 | 0 | 0 | 84720 | 0 | 108800 | 0 | 0 | |
What to Look For
•colls- collisions. If your network is not switched, then a low level of collisions is expected. As the network becomes increasingly saturated, collision will increase and eventually will become a bottleneck. The best solution for collisions is a switched network.
Appendix B Analysis Tools 147
