Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Hierarchical Class of Service Network Scenarios

Hierarchical class of service (HCoS) can be used to provide granular control of traffic for a variety of different applications.


Hierarchical class of service is also referred to as Hierarchical Quality of Service (HQoS) in other vendor’s documentation.

Hierarchical class of service is most frequently used in the following scenarios:

Services to Subscribers

Multiservice network operators face a challenge to provide different types of services on the same infrastructure to residential and business subscribers. The network operator needs to make sure each subscriber gets the network resources they paid for and each service gets the network resources it needs to operate properly.

If no CoS is applied, one service could consume most of the bandwidth of the transmission infrastructure and starve the other services.

Using hierarchical class of service, the network edge device can have up to five levels of scheduling and prioritization. So the traffic can be shaped and prioritized per customer and per service type. Controlling traffic in this way provides the ability to deliver the required service level for each subscriber for each service type.

By allowing network operators to consolidate different services and multiple customers on the same physical infrastructure, hierarchical class of service helps maximize the ability to offer revenue generating services while simultaneously minimizing capital cost.

Services to Businesses

Hierarchical class of service is a valuable tool for service providers that support business customers who are running applications with different prioritization and scheduling requirements over the same infrastructure. In this scenario hierarchical class of service allows lower priority traffic to fully utilize the available bandwidth on a port, while simultaneously ensuring low latency and guaranteed bandwidth to higher priority traffic on the same port.

This allows a provider to consolidate different services on the same physical device and physical infrastructure thus optimizing network resources while maintaining the required level of service.

All of this maximizes revenue and minimizes cost

Wireless Backhaul

In a cellular network the operator might want to offer business services along with its cell tower traffic. One of the main challenges is to make sure that the time-sensitive cell traffic is not affected by the business services running on the same infrastructure. Each type of traffic has its own priority flows and bandwidth constraints. For example, wireless backhaul is very sensitive to fluctuations in the packet stream (Jitter) because it relies on synchronization.

In this scenario, hierarchical class of service allows each type of traffic to receive the required resources and quality of service while being delivered over the same infrastructure.

By consolidate different services on the same physical infrastructure, HCoS helps maximize revenue and minimize cost.