Differentiated Services (DiffServ)

DiffServ is a QoS architecture providing scalable, class-based service differentiation in networks. Introduced by IETF (1998), DiffServ marks packets with a Differentiated Services Code Point (DSCP) in the IP header, enabling routers to apply per-hop-behaviors (PHBs) based on markings. Unlike IntServ (which reserves resources per-flow), DiffServ is stateless and scalable to Internet scale. DiffServ remains the primary QoS mechanism in ISP and enterprise networks.