# Quality of Service (QoS) and bandwidth management

Quality of Service (QoS) Policies are interface-specific rules on a Engine that help you ensure that important network services are given priority over less important traffic.

With QoS rules, you can set up a minimum guaranteed bandwidth and maximum bandwidth limit for traffic, and set a priority value for the traffic. You can optionally define settings for Active Queue Management (AQM) to queue and send traffic according to a scheduling algorithm. Sending traffic reduces the volume of dropped or retransmitted packets when there is network congestion.

You can also create DSCP Match/Mark rules that read or write DiffServ Code Point (DSCP) type of service (ToS) field values. Creating DSCP Match/Mark rules allows you to integrate the Engine with other network equipment that implements QoS management in your own or your ISP’s network.