Custom Queueing or Weighted Round-robin (WRR) is a Queueing mechanism whereby traffic that is allocated is sent as per assignment in a round-robin fashion.
You are able to have upto 16 Queues
i.e. Voice 1 1500
Telnet 2 1500
Default 3 4500
FTP/TFTP 4 6000
so in this scenerio regardless of how much traffic, only the specified traffic limits will be allowed and it will then move onto the next on the list and in the same way round and round until all the traffic has been passed through