Taming the Torrent: A Practical Approach to Reducing Cross-ISP Traffic in Peer-to-Peer SystemsDavid R. Choffnes and Fabián E. Bustamante

Speaker: Wally ChangPublisher: SIGCOMM 2008

MotivationP2P traffic is

massive and random

Transmission usually performs better in the same ISP

Billing problems between ISPs

Previous WorksISPs guide peers for partnership

formation◦Biased peer selection by Bindal et al.

(ICDCS 2006) , Aggarwal et al. (CCR 2007)

and Xie et al. (SIGCOMM 2008)

Remaining issues◦Peer adoption◦Legal problem

Proposed MethodHypothesis

◦If two peers are close to the same CDN replica, they are close to each other

◦Links between “nearby” hosts cross few ISPs

Measuring the relative network distance by comparing name of the CDN replica

CDN Service• The web site with CDN

service will store its components in CDN replica

When a end user visit a web page…◦ Request components

from the web site◦ The CDN DNS will tell

where to get the components

The CDN replica and the end user are “nearby” (SIGCOMM 06)

Comparing the Similarity of CDN replicaRecords the percentage of each

CDN replica

Cosine similarity

Server name

Percentage of connecting to this server

Data CollectionOno

◦An extension to the BitTorrentType of data

◦RTT (ping)◦IP hop (traceroute)◦AS hop (traceroute & AS query tool)

Figures are plotted based on a 2-week study in December, 2007

Reducing Cross-ISP Traffic

Finding Nearby Peers

Ono in Different ISPs (1/3)

Ono in Different ISPs (2/3)

Ono in Different ISPs (3/3)

Using Different CDN Customers

Different CDN customers may have different quality of service in CDN

Effect of Different CDN Customers (1/2)

The more CDN replica names, the better

Effect of Different CDN Customers (2/2)

“AB” is using Limelight CDN service, which is a smaller CDN service company

DiscussionOverhead

◦Requires periodically DNS lookup 18KB up and 36KB down per day

Free-riding on CDN service providers

Practical◦No extra infrastructure needed◦Performance improvement

ReferenceAo-Jan Su et al, “Drafting Behind Akamai

(Travelocity-Based Detouring)”, In Proc. of ACM SIGCOMM 2006., September 2006

Ao-Jan Su et al, ”Relative Network Positioning via CDN Redirections”, In Proc. of the International Conference on Distributed Computing Systems (ICDCS), (to appear) June 2008

David R. Choffnes and Fabián E. Bustamante,” Taming the Torrent: A practical approach to reducing cross-ISP traffic in P2P systems”, In Proc. of ACM SIGCOMM 2008., August 2008.