Evaluation of diffserv-aware constraint-based routing schemes for multiprotocol label switching networks

Differentiated Services (DiffServ) and MultiProtocol Label Switching (MPLS) are attracting attention as Quality of Service (QoS) technologies for the large-scale Internet. DiffServ cannot offer end-to-end QoS by itself, because it controls per-hop packet forwarding order with relative priority according to its class. Achieving end-to-end QoS requires traffic engineering support by using MPLS and Constraint-Based Routing (CBR) schemes in addition to DiffServ. CBR schemes compute explicit routes for Label-Switched Paths (LSPs), which specify packet forwarding routes in MPLS networks. In this paper, we assume two DiffServ classes: Expedited Forwarding (EF) class, which corresponds to voice traffic requiring a low path delay, and Best Effort (BE) class which corresponds to data traffic requiring high throughput. Five DiffServ-aware CBR schemes are constructed, based on route computation algorithms and LSP-types depending on whether or not DiffServ classes are considered. By simulating a path arrangement for two class traffic between every node pair, we evaluate QoS achieved by the five DiffServ-aware CBR schemes. The results show that the scheme that uses different route computation algorithm for each DiffServ class can offer better QoS for each class.