Authors: Vasileios Giotsas, Shi Zhou, Matthew Luckie, KC claffy
Presented By: Vasileios Giotsas
An accurate Internet Autonomous System topology is necessary for a wide range of research problems. AS Topology Data sources include BGP data, Traceroute data, Internet Routing Registries. The available topology datasets are proven to be incomplete. There can be hidden ( Backup / regional transit links ) or invisible links ( Peering links etc. ) The discovery of peering links in IXPs is the key for obtaining complete AS connectivity. (An IXP provides a physical infrastructure to facilitate establishment of peering interconnections.)
This paper addresses the above mentioned AS topology incompleteness problem. Proposes and implements a new approach to infer Multilateral Peering Links, by utilizing only public data sources. Using new techniques to mine IXP route server data with a mapping of BGP community values, this work inferred 206K p2p links from 13 large European IXPs, four times more p2p links than are directly observable in public BGP data. The approach uses only existing BGP data sources, and requires only few active queries of Looking Glass servers, facilitating reproducibility of the results.
Limitations: Where the method can’t be applied.
- IXPs without Route Servers.
- Route Servers that do not use BGP Communities for advertisement.
- Route Servers that strip out BGP Communities before propagating advertisements.
The entire study is based on European IXPs, but they plan to soon extend it over N. America and Asia-Pacific regions as well.
Q: How hard it is to get peering data?
A: The data has to be collected in a distributed manner. Obviously it is labour intensive, data cleaning required. These IXPs are some of the world’s largest.
Q: How static/dynamic were they (links)?
A: There might be very frequent updates on topology. The study is one snapshop carried over for several days. If one single link leaves (taken out etc.) all paths change. The dynamicity would be even more for bilateral cased (N(N-1)/2 connections) and might be a bit less for multilateral.