An MPLS-based Quality of Service Architecture for Heterogeneous Networks

by Raghavan, Srihari

This thesis proposes a multi-protocol label switching (MPLS)-based architecture to provide quality of service (QoS) for both internet service provider (ISP) networks and backbone Internet Protocol (IP) networks that are heterogeneous in nature. Heterogeneous networks are present due to the use of different link-layer mechanisms in the current Internet. Copper-based links, fiber-based links, and wireless links are some examples of different physical media that lead to different link-layer mechanisms. The proposed architecture uses generalized MPLS and other MPLS features to combat heterogeneity. The proposed architecture leverages the QoS capabilities of asynchronous transfer mode (ATM) and the scalability advantages of the IP differentiated services (DiffServ) architecture. This architecture is constructed in such a way that MPLS interacts with DiffServ in the backbone networks while performing ATM-like QoS enforcement in the periphery of the networks. The architecture supports traffic engineering through MPLS explicit paths. MPLS network management, bandwidth broker capabilities, and customizability is handled through domain specific MPLS management entities that use the Common Open Policy Service (COPS) protocol to interact with other MPLS entities like MPLS label switch routers and label edge routers. The thesis provides a description of MPLS and QoS, followed by a discussion of the motivation for a new architecture. The MPLS-based architecture is then discussed and compared against similar architectures. To integrate the ATM and DiffServ QoS attributes into this architecture, MPLS signaling protocols are used. There are two common MPLS signaling protocols. They are Resource Reservation Protocol with traffic engineering extensions (RSVP-TE) and Constraint-Routed Label Distribution Protocol (CR-LDP). Both these protocols offer comparative MPLS features for constraint routed label switch path construction, maintenance, and termination. RSVP-TE uses UDP and IP, while CR-LDP uses TCP. This architecture proposes a multi-level domain of operation where CR-LDP operates in internet service provider (ISP) networks and RSVP- TE operates in backbone networks along with DiffServ. Qualitative analysis for this choice of domain of operation of the signaling protocols is then presented. Quantitative analysis through simulation demonstrates the advantages of combining DiffServ and MPLS in the backbone. The simulation setup compares the network performance in handling mixed ill-behaved and well-behaved traffic in the same link, with different levels of DiffServ and MPLS integration in the network. The simulation results demonstrate the advantages of integrating the QoS features of DiffServ, ATM functionality, and MPLS into a single architecture.