Dynamic congestion control mechanisms for MPLS networks

Considerable interest has arisen in congestion control through traffic engineering from the knowledge that although sensible provisioning of the network infrastructure is needed, together with sufficient underlying capacity, these are nor sufficient to deliver the Quality of Service (QoS) required for new applications. This is due to dynamic variations in load. In operational Internet Protocol (TP) networks, it has been difficult to incorporate effective traffic engineering due to the limited capabilities of the IP technology. In principle, Multiprotocol Label Switching (MPLS), which is a connection-oriented label swapping technology, offers new possibilities in addressing the limitations by allowing the operator to use sophisticated traffic control mechanisms. This paper presents a novel scheme to dynamically manage traffic flows through the network by re-balancing streams during periods of congestion. It proposes management-based algorithms that will allow label switched routers (LSRs) within the network to utilise mechanisms within MPLS to indicate when flows are starting to experience frame/packet loss and then to react accordingly. Based upon knowledge of the customers' Service Level Agreement (SLAs), together with instantaneous flow information, the label edge routers (LERs) can then instigate changes to the LSP route and circumvent congestion that would hitherto violate the customer contracts.