Differentiated-Services-Aware Traffic Engineering Terminology

The following terminology applies to differentiated-services-aware traffic engineering:

• Bandwidth model—The bandwidth model determines the values of the available bandwidth advertised by the interior gateway protocols (IGPs).
• CAC—Call admission control checks to ensure there is adequate bandwidth on the path before the LSP is established. If the bandwidth is insufficient, the LSP is not established and an error is reported.
• Class type—A collection of traffic flows that is treated equivalently in a differentiated services domain. A class type maps to a queue and is much like a class-of-service (CoS) forwarding class in concept. It is also known as a traffic class.
• Differentiated services—Differentiated services make it possible to give different treatment to traffic based on the experimental (EXP) bits in the MPLS header. Traffic must be marked appropriately and CoS must be configured.
• Differentiated services domain—The routers in a network that have differentiated services enabled.
• Differentiated-services-aware traffic engineering—A type of constraint-based routing. It can enforce different bandwidth constraints for different classes of traffic. It can also do CAC on each traffic engineering class when an LSP is established.
• Multiclass LSP—A multiclass LSP functions like a standard LSP, but it also allows you to reserve bandwidth from multiple class types. The EXP bits of the MPLS header are used to distinguish between class types.
• MAM—The maximum allocation bandwidth constraint model divides the available bandwidth between the different classes. Sharing of bandwidth between the class types is not allowed.
• RDM—The russian dolls bandwidth constraint model makes efficient use of bandwidth by allowing the class types to share bandwidth.
• Traffic engineering class—A paired class type and priority.
• Traffic engineering class map—A map between the class types, priorities, and traffic engineering classes. The traffic engineering class mapping must be consistent across the differentiated services domain.