DNSR:DNSR: DDomain omain NName ame SSuffix-based uffix-based RRouting in outing in Overlay NetworksOverlay Networks

Demetrios Zeinalipour-Yazti

Dept. of Computer Science & Engineering.

University of California - Riverside

CS202 – Advanced O.S Spring ’03

IntroductionIntroduction

AverageRTT=9ms4 Router Hops

AverageRTT=140ms19 Router Hops

AverageRTT=163ms19 Router Hops

pc-62-30-117-83-cr.blueyonder.co.uk

p237-165.yahoo.co.jp

roc-24-169-109-208.rochester.rr.com

12-224-0-236.client.attbi.com

AverageRTT=46ms13 Router Hops

AverageRTT=130ms22 Router Hops

66-215-0-xxx.oc-nod.charterpipeline.net

66-215-0-xxx.oc-nod.charterpipeline.net

London

AtlantaRochester

Tokyo

Riverside

• Most overlay networks don’t match the underlying topology

• Transcontinental connections are expensive.• It would be desirable to keep the bulk of the

P2P traffic within the same domain

• Analyzing the Gnutella Network [D. Zeinalipour & T. Folias, cs204 Course Project]

– We analyzed ~300,000 IP addresses.– 58.73% of Gnutella IPs belongs to only 20 ISPs.– Organizing Peers into domains rather than

loosely interconnecting them might be feasible

MotivationMotivation

• DNSR:Domain-Name Suffix-based Routing – Decentralized Routing Algorithm that attempts to keep

P2P traffic within the same domain.– DNSR defines three Level factors per peer:

• Sibling Factor (sfi)• Parent Factor (pfi)• Children Factor (cfi)

– DNSR also defines a similarity function -suffix

DNSR IdeaDNSR Idea

ni=cs6368146-17.austin.rr.com

nj=node-17.rr.com

sfi=0.8

pfi=cfj=0.1di=10

*.austin.rr.com

cfi=0.1

• Given that each node maintains the Level Factors we end up with a semi-hierarchical topology.

DNSR TopologyDNSR Topology

Level 1 Level 1

Level 2

n1.ucr.edu

n1.cs.ucr.edu

n2.cs.ucr.edu

n3.cs.ucr.edu

n2.ucr.edun6.ucsd.edu

n2.cs.ucr.edu

n2.cs.ucr.eduLevel 2

n2.cs.ucsd.edu

n3.cs.ucsd.edu

n2.cs.ucsd.edu

DNSR Topology Instancedi = 3--------------pfi = di / 3sfi = di / 3cfi = di / 3

JoiningJoining a DNSR Topology a DNSR Topology

Level 1 Level 1

Level 2

n1.ucr.edu

n1.cs.ucr.edu

n2.cs.ucr.edu

n2 = n3.cs.ucr.edu

n3 = n2.ucr.edun4 = n6.ucsd.edu

n2.cs.ucr.edu

n1 = n2.cs.ucr.eduLevel 2

n2.cs.ucsd.edu

n5 = n3.cs.ucsd.edu

n2.cs.ucsd.edu

Domain-Name Lookup in DNSR Topology

Lookup

OverlayConnection

nj = n5.cs.ucsd.edu

Lookup Response

• A node obtains a random list from an out-of-band mechanism (e.g. hostcache).

• It probes for “best” entry point with Lookup

• Searching can be done with a variety of techniques (BFS, Random BFS,….)

• The bottom-line with all techniques is that the bulk of the traffic remains within the same domain

SearchingSearching a DNSR Topology a DNSR Topology

Level 2

Level 1n1.ucr.edu

n1.cs.ucr.edu

n2.cs.ucr.edu

n2 = n3.cs.ucr.edu

n3 = n2.ucr.edu

n2.cs.ucr.edu

n1 = n2.cs.ucr.edu

Searching in DNSR Topology using BFS

QUERY

QUERYHIT

Scenario• We generate a DNSR topology and a Random

Topology of 1000 nodes with following distributions

• We deploy the 1000 real nodes on 25 machines• We run a number of queries and observe the

distribution of hosts contacted in each case.

Experimental SetupExperimental Setup

• Each node reads its settings from the filesystem

• All nodes are launched concurrently with ssh public/private keys making the bootstrapping easy.

Experimental EvaluationExperimental Evaluation

• We connect to a .rr.com host

• Submit 40 queries and count the number of hosts contacted C.

• In a random topology C matches the actual distribution of hosts

• In a DNSR topology most of the hosts contacted are .com hosts for level 0.

Experimental ResultsExperimental ResultsLevel 0

• For Level 1 we can see that in DNSR topology we will contact more .rr.com hosts than with a random topology.

• Therefore more traffic remains within same domain

• Sibling Factor was 66%. If it was larger then 24% would be larger

Experimental ResultsExperimental ResultsLevel 1

DNSR Demo Follows…DNSR Demo Follows…

Dept. of Computer Science & Engineering.

University of California - Riverside