Mechanisms for Enhancing the Reliability and Performance of a MPOA Client
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2003-Jun-18
A mechanism is disclosed for enhancing the reliability and performance of a MPOA client through the utilization of multiple ATM interfaces. The ATM interface associated with a MPOA Client (MPC) may be both a single point-of-failure and a potential performance bottleneck. This is a problem that must be addressed before MPOA equipment can be installed in many mission-critical networking environements. The solution is based on utilization of multiple ATM interfaces to improve reliability by eliminating the single point-of-failure and offer additional perforamance via load-balancing techniques. Before describing the details of the solution, we will first provide some background information about the MPOA protocol. Background: MultiProtocol Over ATM (MPOA) is a client-server protocol that was starndardized by the ATM Forum. MPOA Servers (MPSs) are co-located with routers, while MPOA Clients (MPCs) reside in end stations or edge switches. In this disclosure, we will focus on MPCs that reside in edge switches. One of the fundamental characteristics of an edge switch is that it performs LAN-to-ATM bridging. MPOA relies on this capacity. The MPC adds additional function on top of this bridging base. MPCs dynamically discover MPSs and monitor the traffic flowing to routers' MAC addresses. When the amount of traffic flowing to a given layer-3 destination exceeds a threshold, the MPC issues a resolution request for the layer-3 destination. The request flows through the MPSs along the routed path to the destination. Eventually, the request reaches the egress MPC at the edge of the ATM network. The MPC provides an ATM address through which the layer-3 destination can be reached. This ATM address is returned to the ingress MPC. The ingress MPC then sets up an ATM VCC to the egress MPC. Subsequent data destined for the layer-3 destination is transmitted over the shortcut VCC to the egress MPC. Subsequent data destined for the layer-3 destination is transmitted over the shortcut VCC bypassing intermediate routers and improving overall system performance. In the absence of a shortcut for a given layer-3 destination, the edge device simply bridges LAN traffic destined for an ATM-attached MPS-router. This traffic is bridged to an ATM Emulated LAN (ELAN) via a LAN Emulation Client (LEC).