Flood Avoidance Mechanisms for Bridged Resilient Packet Rings

Resilient Packet Ring (RPR), or the Standard IEEE 802.17, is a new IP-based networktechnology proposed to replace SONET/SDH in metropolitan areanetworks. RPR is well-adapted to handle multimedia traffic and isefficient. However, when RPR networks are bridged, inter-ring packets,or packets with the destination on a remote RPR network other than onthe source network, are flooded on the source and the destinationnetworks, and also on the path of the intermediate networks betweenthe source and the destination networks. This decreases the availablebandwidth for other traffic in those networks and is inefficient. Asa result, we propose two solutions based on topology discovery,global topology discovery (GTD) and enhanced topology discovery(ETD), that prevent the flooding of inter-ring packets. GTD enables thebridges to determine the next-hop bridge for each destination. ETDenables the source node to determine a default ringlet, so thatpackets reach the next-hop bridge without flooding the sourcenetwork. The proposed solutions were analyzed and the overheadbandwidth and stabilization time were shown to be bounded.Simulations performed showed that the proposed solutionssuccessfully avoid flooding and achieve optimal efficiency in theintermediate and destination networks, and in the source networkswith one bridge.