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Abstract-Newly announced IP addresses (from previously unused IP blocks) are often unreachable. It is common for network operators to filter out address space which is known to be unallocated ("bogon" addresses). However, as allocated address space changes over time, these bogons might become legitimately announced prefixes. Unfortunately, some ISPs still do not configure their bogon filters via lists published by the Regional Internet Registries (RIRs). Instead, they choose to manually configure filters. Therefore it would be desirable to test whether filters block legitimate address space before it is allocated to ISPs and/or end users. Previous work has presented a methodology that aims at detecting such wrongly configured filters, so that ISPs can be contacted and asked to update their filters. This paper extends the methodology by providing a more formal algorithm for finding such filters, and the paper quantitatively assesses the performance of this methodology.

Abstract. Humpty Dumpty is the anthropomorphic nursery-rhyme egg broken into many pieces. Similarly, we have many pieces of measurement data to represent the current iBGP state. However, unlike the nurseryrhyme where the King's men couldn't put Humpty together again, we present a systematic approach to putting all the pieces of measured iBGP data together to obtain a more complete picture of a network's routing state.Our technique determines the decisions made by all routers in a network. It is efficient, has no assumptions about router configuration and is accurate. We present a case-study of a large Tier-2 ISP, finding for those routers with adequate measurement infrastructure, we consistently find the egress location for 99.9999% of (router, prefix) pairs. Further, for the 85% of routers without measurement infrastructure we predict their decisions. This technique has been successfully applied in a 'what-if' scenario and has future applications in the real-time analysis of routing decisions.

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A growing area of technical importance is that of distributed virtual environments for work and play. For the audio component of such environments to be useful, great emphasis must be placed on the delivery of high quality audio scenes in which participants may change their relative positions. In this paper we describe and analyze an algorithm focused on maintaining relative synchronization between multiple users of such an environment and examine the subjective quality of service achieved. Disciplines Physical Sciences and Mathematics Publication DetailsThis article was originally published as: