Simulation of MPLS Traffic Engineering on OPNET Modeler

Switches were initially designed to minimize multiple collision domains. When switching is used in a LAN to connect individual client and server computers, the collision domain has been reduced to just the switch and the computer attached to a port.

Where large volumes of data need to be routed through a large corporate network or the Internet, for that matter even the fastest traditional routers or layer 3 switches easily can become bogged down by the volume of traffic. Because of this, the core of a large network traditionally has been built using ATM or Frame Relay switches, and IP traffic is sent over these switched networks.

To speed up the processing of routing packets at high-volume rates, a newer technology has been developing over the past few years and goes by the name of Multi-Protocol Label Switching (MPLS).

MPLS using special routers called Label Switching Routers (LSRs) perform this task. These routers connect a traditional IP network to an MPLS network. A packet enters the MPLS network through ingress LSR, which attaches a label to the packet, and exits the MPLS switched network through an egress LSR. The ingress LSR is the router that performs the necessary processing to determine the path a packet will need to take through the switched network. This can be done using traditional routing protocols such as OSPF. The path is identified by the label that the ingress router attaches to the packet. As you can see, the ingress router must perform the traditional role that a router fills. It must perform a lookup in the routing table and decide to which network the packet needs to be sent for eventual delivery to the host computer.

Traffic Engineering is the process where data is routed through the network according to a management view of the availability of resources and the current and expected traffic. The class of service and quality of service required for the data can also be factored into this process.

Traffic Engineering may be under the control of manual operators. Alternatively, Traffic Engineering may be driven by automated processes reacting to information fed back through routing protocols or other means.

Traffic Engineering helps the network provider make the best use of available resources, and allowing some links to be reserved for certain classes of traffic or for particular customers. One of the main uses for MPLS will be to allow improved Traffic Engineering on the ISP backbone networks.

Traffic Engineering is also implemented by using Resource Reservation Protocol (RSVP). It sends request message for bandwidth checking whether available or not in path message and if available then confirmation message is received in RESV message and it allows the formation of tunnel. Apart from that it has some other additional features i.e. Explicit routing, Reservation of Bandwidth for LSP and finding the actual route of an LSP using RRO (record Route Object).