Often your router will collect this data over some period, just check its logs. It may show it on a status page, too. Otherwise, it does involve logging to a remote log server or using SNMP to collect the info on another machine if your router supports SNMP.
If your router doesn't support it, it willbe more difficult to do and involve something like putting a machine in the routing path, or contacting your ISP for this info, if they collect it.