All-path bridging: Path exploration as an efficient alternative to path computation in bridging standards

摘要

Link-state based routing protocols are dominant in Shortest Path Bridges (IEEE 802.1aq) and also at TRILL (IETF) Rbridges. Both standards propose a hybrid of switch and router adding a link state routing protocol in layer two that computes shortest paths between bridges. Surprisingly, path exploration mechanisms have not yet been considered at standardization bodies, in spite of some outstanding advantages: simplicity, instantaneous path adaptation to traffic load with load adaptive routing and low latency. We have developed All-path, a family of protocols based on simple path exploration mechanisms based on full flooding of a single frame, as an alternative to the “beaten trail” of path computation. Path exploration (either instantaneous or periodical, proactive or reactive) is an efficient alternative to path computation for bridged networks because the processing cost of address learning at bridges from broadcast frames is very low and Ethernet links provide very high link capacity so that the extra packet broadcasts do not impact load significantly. Standardization groups should consider the application of path exploration (instantaneous or periodical, proactive or reactive) mechanisms in Audio Video Bridges and in generic bridging networks like campus and data centers to find redundant paths, low latency and load distribution in simple ways instead of complex multiple path computations.