Transcript DNSR: Domain Name Suffix-based Routing in Overlay Networks

Dept. of Computer Science & Engineering.
University of California - Riverside
CS202 – Advanced O.S Spring ’03
DNSR: Domain Name
Suffix-based Routing in
Overlay Networks
Demetrios Zeinalipour-Yazti
Introduction
• 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
pc-62-30-117-83-cr.blueyonder.co.uk
12-224-0-236.client.attbi.com
AverageRTT=46ms
13 Router Hops
Tokyo
Atlanta
London
AverageRTT=163ms
19 Router Hops
Rochester
roc-24-169-109-208.rochester.rr.com
p237-165.yahoo.co.jp
AverageRTT=140ms Riverside
19 Router Hops
AverageRTT=130ms
22 Router Hops
66-215-0-xxx.oc-nod.charterpipeline.net
AverageRTT=9ms
4 Router Hops
66-215-0-xxx.oc-nod.charterpipeline.net
Motivation
• 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
DNSR Idea
• 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
nj=node-17.rr.com
pfi=cfj=0.1
 -suffix
di=10
sfi=0.8
ni=cs6368146-17.austin.rr.com
cfi=0.1
*.austin.rr.com
DNSR Topology
• Given that each node maintains the Level
Factors we end up with a semihierarchical topology.
di = 3
-------------pfi = di / 3
sfi = di / 3
cfi = di / 3
DNSR Topology Instance
n6.ucsd.edu
Level 1
n2.ucr.edu
n1.cs.ucr.edu
n3.cs.ucsd.edu
n2.cs.ucsd.edu
n1.ucr.edu
n2.cs.ucsd.edu
Level 2
Level 1
n3.cs.ucr.edu
n2.cs.ucr.edu
n2.cs.ucr.edu
n2.cs.ucr.edu
Level 2
Joining a DNSR Topology
• A node obtains a random list from an out-ofband mechanism (e.g. hostcache).
• It probes for “best” entry point with Lookup
Domain-Name Lookup in DNSR Topology
Lookup
Lookup Response
Overlay
Connection
n4 = n6.ucsd.edu
Level 1
n2.cs.ucsd.edu
Level 2
Level 1
n2 = n3.cs.ucr.edu
n1.cs.ucr.edu
n5 = n3.cs.ucsd.edu
n2.cs.ucsd.edu
n3 = n2.ucr.edu
n1.ucr.edu
n1 = n2.cs.ucr.edu
n2.cs.ucr.edu
Level 2
n2.cs.ucr.edu
nj = n5.cs.ucsd.edu
Searching a DNSR Topology
• 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
Searching in DNSR Topology using BFS
QUERY
n3 = n2.ucr.edu
n1.ucr.edu
Level 1
QUERYHIT
n2 = n3.cs.ucr.edu
n1.cs.ucr.edu
n1 = n2.cs.ucr.edu
n2.cs.ucr.edu
n2.cs.ucr.edu
Level 2
Experimental Setup
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 Evaluation
• Each node reads its settings from the filesystem
• All nodes are launched concurrently with ssh
public/private keys making the bootstrapping
easy.
Experimental Results
• 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.
Level 0
Experimental Results
• 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
Level 1
Dept. of Computer Science & Engineering.
University of California - Riverside
DNSR Demo Follows…