AUTHOR: SIMON GREENER This talk will attempt a review of the geospatial data space within Australia. The talk will outline who the main players are, what spatial data is available, and the licensing options that cover their use. An assessment of the licenses will be made. In particular the talk will outline the data that is available for free and, and after establishing the various uses of that data, assess how important that data is to various sectors and individuals within society and how it might benefit society as a whole.

1. Sequoia: Virtual-Tree Models for
Internet Path Metrics
Rama
Microsoft Research
Also: Ittai Abraham (Hebrew Univ.)
Mahesh Balakrishnan (Cornell)
Archit Gupta (Univ. Wisc.)
Fabian Kuhn (EPFL)
Dahlia Malkhi (MSR)
Kunal Talwar (MSR)

2. Introduction
Goal: Model properties (latency, bandwidth)
of paths between Internet end hosts

3. Applications
• “what’s the server with the largest bandwidth
that the client can download content from?”
– Content distribution
• “what’s the relay node that gives the shortest
delay VoIP connection between two users?”
– VoIP routing
• “what’s the best server to coordinate the online
game between a set of players?”
– Online gaming

4. Sequoia Virtual Trees
• Network embedding into
trees R
—Leaf nodes (A, B, C, R)
are end hosts
Internet
A B C

5. Sequoia Virtual Trees
• Network embedding into
trees R
—Leaf nodes (A, B, C, R)
are end hosts t
—Inner nodes (s, t) are s
“virtual”
A B C

6. Sequoia Virtual Trees
• Network embedding into
trees R
80
—Leaf nodes (A, B, C, R)
are end hosts t
10
—Inner nodes (s, t) are s
“virtual”
2
1 20
—Edge weights model path
property A B C

7. Accuracy of Virtual-Tree Models
Relative Error
PlanetLab King PlanetLab
Latency Latency Bandwidth
125 nodes 2500 nodes 390 nodes
Median 14 % 20 % 24 %
75th p.c. 22 % 35 % 41 %
90th p.c. 50 % 56 % 65 %

8. Distance Labels a.k.a ‘‘Coordinates’’
• Distance Label = Path to the Root
R
– Example: A: (s,t,R) and C: (t,R)
80
• Trivial to estimate quality of paths t
– Latency: d(A,C) = d(A,s) + d(s,t) + d(t,C) 10
s
• As convenient as coordinate-based
2
1 20
systems
A B C

9. Sequoia
Tree for
PlanetLab
Latencies

10. Hierarchical Clustering for
PlanetLab Nodes in Europe
Spain and Portugal
UK and Ireland
Scandinavia

11. Summary
• Virtual Trees to Model Internet Path Metrics
• Predict Bandwidth and Latency
• Convenient ‘‘Coordinates’’
• Hierarchical Clustering
http://research.microsoft.com/research/sv/sequoia