How to monitor network bandwidth usage?

view story

http://serverfault.com – Can we get the network bandwidth usage statistics (of single computer) within a LAN by using SNMP queries? Thanks. Edit: I mean to say that we can query a router to get informations such as number of interfaces, total bandwidth usages etc. So my question is that does the router have information about bandwidth usage of patriculat host in a network, so that i can query the information from it, if the router exposes those information via snmp protocol. (HowTos)