DiffServ CoS Simulation -- IP VPN Case Study

Whatever the end-to-end mechanisms used for ensuring Quality of Service (QoS) for SIP individual application flows, this QoS is dependent on the QoS offered by service providers in the crossed networks. With DiffServ, individual flows are classified and aggregated when entering the backbone. This white paper analyses the simulation of classes of services over an IP/MPLS backbone combining DiffServ and Traffic Engineering.

White Paper: Simulating DiffServ Classes of Service over an IP/MPLS Backbone

Figure 1 shows an SP (service provider) network that offers VPN services to 3 customers: Red, Blue and Green. The internal backbone links connecting the edge routers to the core routers are limited to STM-1 in order to cope with the traffic throughput used in the context of this case study. The other backbone links between core routers are either STM-1 or STM-4, thus creating the conditions for over-sizing or under-sizing. This core network topology ensures a minimum of resiliency since each PE (Provider Edge) router is connected to two P (Provider core) routers and each P router is in turn connected to two other P routers. However, the links in dotted lines will not be considered for this case study, not to complicate the simulation survey.

The distances (not shown) between the backbone routers represent a realistic regional network, either national or international. We consider primarily MPLS VPN services over this network but other services such as Internet Transit could be offered as well. In some scenarios we will introduce extra flows crossing the SP network and we can consider that these flows could belong to traffic related to other VPN, or Internet Transit, services.

Links to WP's References