Chapter 12. Quality of Service and Resource Allocation

Recall from Chapter 3 that the main portion of the port processor interface in routers supports quality of service (QoS). This chapter explores all angles of QoS and the numerous methods of providing it at various protocol stack layers . This chapter covers the following topics:

• Overview of QoS

• Integrated services QoS

• Traffic shaping

• Admission control

• Reservation protocol (RSVP)

• Differentiated services QoS

• Resource allocation

Two broad approaches to QoS are integrated services and differentiated services . Integrated services provide QoS to individual applications and flow records. Providing QoS requires certain features to be maintained in switching nodes. QoS protocols govern traffic shaping and packet scheduling. Traffic shaping regulates the spacing between incoming packets. Other advanced QoS protocols covered are admission control and RSVP.

The differentiated services provide QoS support to a broad class of applications. The basics of resource allocation for packet-switched networks are reviewed, as is resource allocation for all possible layers of the protocol stack. Resource-allocation algorithms can be used to avoid possible ATM congestion.