JUNOS : class of service (CoS)

The Juniper Networks® Junos® operating system (Junos OS) class of service (CoS) enables you to divide traffic into classes and offer various levels of throughput and packet loss when congestion occurs. This allows packet loss to happen according to rules that you configure.

For interfaces that carry IPv4, IPv6, and MPLS traffic, you can configure the Junos OS CoS features to provide multiple classes of service for different applications. On the router, you can configure multiple forwarding classes for transmitting packets, define which packets are placed into each output queue, schedule the transmission service level for each queue, and manage congestion using a random early detection (RED) algorithm.

The Junos OS CoS features provide a set of mechanisms that you can use to provide differentiated services when best-effort traffic delivery is insufficient. In designing CoS applications, you must give careful consideration to your service needs, and you must thoroughly plan and design your CoS configuration to ensure consistency across all routers in a CoS domain. You must also consider all the routers and other networking equipment in the CoS domain to ensure interoperability among all equipment.

Because Juniper Networks routers implement CoS in hardware rather than in software, you can experiment with and deploy CoS features without adversely affecting packet forwarding and routing performance.