Possible Reasons for LAN Traffic Congestion

If you are experiencing slowness on your LAN here are some possible reasons that you can investigate:

– low bandwidth
– broadcast storms (can be caused by network loops or hosts with the same IP)
– excessive multicast traffic
– too many hosts in a broadcast or collision domain
– failing router/switch

The above are some possible reasons of LAN traffic congestion. Now why you have broadcast storms or why you have excessive multicast traffic can be another story. Once you know the reason and generally where the congestion is occurring you may want to try to get to the exact root cause such as bad network topology, DNS errors, virus/spyware infections, bandwidth-hogging network-based applications, or end-user behavior (downloading huge files, peer-to-peer file sharing, playing heavy-bandwidth consuming online games, etc.).