Routers are designed with Quality of Service (QoS) mechanisms on both ingress and egress to support multiple customers and multiple services per physical interface. The routers can classify, police, shape, and mark traffic.
In the Nokia service router service model, a service is provisioned on the provider-edge (PE) equipment. Service data is encapsulated, then sent in a service tunnel to the far-end Nokia service router where the service data is delivered.
The operational theory of a service tunnel is that the encapsulation of the data between the two Nokia service routers (such as the 7950 XRS, 7750 SR, 7750 SR MG, and 7450 ESS) appears like a Layer 2 path to the service data although it is really traversing an IP or IP/MPLS core. The tunnel from one edge device to the other edge device is provisioned with an encapsulation and the services are mapped to the tunnel that most appropriately supports the service needs.
The router supports eight forwarding classes internally named:
Network-Control
High-1
Expedited
High-2
Low-1
Assured
Low-2
Best-Effort
The forwarding classes are described in more detail in Forwarding classes chapter.
Router QoS policies control how QoS is handled at distinct points in the service delivery model within the device. There are different types of QoS policies that cater to the different QoS needs at each point in the service delivery model. QoS policies are defined in a global context in the router and only take effect when the policy is applied to a relevant entity.
QoS policies are uniquely identified with a policy ID number or name. Policy ID 1 or Policy ID ‟default” is reserved for the default policy that is used if no policy is explicitly applied.
The QoS policies within the router can be divided into three main types:
QoS policies are used for classification, defining and queuing attributes, and marking.
Slope policies define default buffer allocations and WRED slope definitions.
Scheduler policies determine how queues are scheduled.