Communication NetworksWei Lu, Sireen Malik
Simulating Gnutella 0.6
Student Project Final PresentationWei Lu 02.2005
-2-Communication NetworksWei Lu, Sireen Malik
Gnutella• Gnutella 0.4
– Distributed Index Flooding Architecture (DIFA)
– Signaling• Attempt connection with Bootstra
p servers• Once connected, flood PINGS• Reverse routed PONGS from kno
wn-hosts• PONG-based connection to know
n hosts• Flood QUERIES to all known-ho
sts• Reverse routed QUERYHITS
– File download via HTTP-TCP[Source:P2P Traffic Simulation, Sireen Malik, Prof. Ulrich Killat]
• Gnutella 0.6– Two-layered hierarchy
• Supernodes (called Ultrapeers) • Client nodes (called Shielded Leave
s)• Ultrapeers: faster,better networking
and CPU power act as proxies for client(leaf) nodes connected to them shield leaf nodes from almost all ping and query traffic
-3-Communication NetworksWei Lu, Sireen Malik
Gnutella 0.6, Anti-flooding
• Message Dispatching– Leaf node doesn't relay Ping message– Ultrapeer only dispatches Ping message to
other connected Ultrapeers.• Query Routing
– Leaf node doesn't spread Query message.– Ultrapeer only dispatches Query message to oth
er Ultrapeer and some of his leaf nodes selectively (DIHA).
-4-Communication NetworksWei Lu, Sireen Malik
Gnutella 0.6, Ultrapeer Election• New header fields for handshaking
– X-Ultrapeer, whether a host plans on acting as ultrapeer– X-Ultrapeer-Needed, to balance the number of ultrapeers
• Handshaking– Leaf to Ultrapeer, Leaf to Shielded Leaf, Leaf to Unshielded Leaf,
Ultrapeer to Ultrapeer
• Specification is quite open on details– Max-number of leaves (Cluster Size): LimeWire 30, BearShare 45.– Ultrapeer critera: “at least 15KB/s downstream and 10KB/s upstre
am”, “have been running for few hours/sever minutes”, “when (not) too many”…
• Ultrapeer : ?%, Leaf: ?%
-5-Communication NetworksWei Lu, Sireen Malik
Optimal Topology
• What’s the globally optimal topology? (% of UltrapeerCluster size, Degree distribution, etc.)
• How to locally approach the optimal topology?(Ultrapeer criteria, Routing protocol)
-6-Communication NetworksWei Lu, Sireen Malik
Optimal Topology, Q1• Analytic model: not well established yet.
– Parameters• Ultrapeer percentage, Cluster Size, Degree distribution Pd, TTL, Q
uery rate Rq, Replication rate Rr, …– Objectives
• Load (Computation, Communication), Quality of result, …– Random Graph, Load{QueryTraffic[QueryCoverage(Pd, T
TL)], QueryHitTraffic(Rr, Rq)}. Hard to calculate.[1]– Var(load(p)/CHL(p)), recursive function, simulated annealin
g to calculate.[2]• Measurement: strongly related to software configurat
ion/ protocol implementation.
-7-Communication NetworksWei Lu, Sireen Malik
Optimal Topology, Q2
• [3] gives rules of thumb.– But the model based on semi-p2p system (superp
eer (server) is at most 1 hop away) might not be accurate enough.
• Cluster head selection in ad-hoc and sensor network[4][5]. – Based on Node ID, Node degree. Optimize pow
er consumption (load), communication, etc.
-8-Communication NetworksWei Lu, Sireen Malik
Optimal Topology, dynamic network
• Most of above works are based on static context.
• Peer availability matters.
-9-Communication NetworksWei Lu, Sireen Malik
Current Approach
• Related to Implementation[Daniel Stutzbach, Reza Rejaie, “Characterizing Today’s Gnutella Topology”, Dec.2004]
• Our config:5% Ultrapeer.
-10-Communication NetworksWei Lu, Sireen Malik
Implementation, NS-2
GnutellaServentGnutellaApp
TclObject
GnutellaGlobalRegistrationOffice
GnutellaConnection
TcpAgent
-tcp_send,tcp_sink,dst_send,dst_sink 1*
-connection_list_
1
*
-gnuProt_
1
-gnutella_appl_
*
Node
-node_
1
-node_ 1
-app_ 1
• Extending Gnutella 0.4: Ultrapeer Election, DIHA, Downloading, ...
• Facilities: control of selected peers, trace on link, random seed, ...
-11-Communication NetworksWei Lu, Sireen Malik
Implementation, Ptolemy
• Ptolemy– Adapting NS-2 code to Ptolemy.– No modification, just re-compile.
Real World NS-2 Ptolemy
Network Interface Node Star / Galaxy
TCP Agent Star / Galaxy
Gnutella Application Star / Galaxy
Adapter
Adapter
-12-Communication NetworksWei Lu, Sireen Malik
Configuration – User Model• All MODEM & DSL users in ON/OFF process
– mean on 60 sec, log quadratic; mean off 105 sec, neg. exp.
• Every 25s, drops oldest connections when many• File size distribution:
– for < 10MB files (music) less than 15% bytes but more than 88% request
– for >100MB files (movies) more than 65% bytes but less than 5% request
• Number of files shared by peers– 66% free-riders, 73% share 10 or less files, top 1%
share 35% files
-13-Communication NetworksWei Lu, Sireen Malik
Configuration – Network• Germany Network, 17
core nodes.• Power Law for 2nd level
node connectivity (Pareto Distribution, Shape 1.5)
• Bandwidth of 2nd level nodes (70% MODEM, Uniform Distribution)
-14-Communication NetworksWei Lu, Sireen Malik
Result – Average Signaling Traffic MODEM (100Kbps)
-15-Communication NetworksWei Lu, Sireen Malik
Result – Average Singling Traffic DSL (1~4Mbps)
-16-Communication NetworksWei Lu, Sireen Malik
Result – Average Signaling Traffic Bootstrap (1000Mbps)
-17-Communication NetworksWei Lu, Sireen Malik
Result – Signaling Sum-up• MODEM(100Kbps):
70%, DSL(1~4Mbps): 29.6% , Bootstrap(1000Mbps) : 0.4%.
• 35>1/5% (5% peers behave as in 0.4)– Less peers flood
message.– Message flooded in
smaller scope35)(
6.0
4.0 MsgRateMsgRateMean
-18-Communication NetworksWei Lu, Sireen Malik
Downloading• Previous configurations, e.g. File size distribution:
• Each QueryHit triggers a HTTP session for downloading.
• Result: QueryHit/Query = 34.73%
-19-Communication NetworksWei Lu, Sireen Malik
Result – Gnutella 0.6 Signaling and Signaling+Downloading
• By single MODEM(100Kbps) and DSL(1Mbps) user
• Signaling is minor part.• Log-Log scaled • MODEM:
– Synthesis ≈ 100 Signaling
• DSL:– Synthesis ≈ 1000 Signaling
-20-Communication NetworksWei Lu, Sireen Malik
References• [1] Ruediger Schollmeier, Gero Schollmeier, An analytic
model for the behavior of arbitary peer-to-peer networks.• [2] Mudhakar Srivatsa, Bugra Gedik, Ling Liu, Improving
Peer to Peer Search With Multi-tier Capability-Aware Overlay Topologies.
• [3] Beverly Yang, Hector Garcia-Molina, Designing a Super-Peer Network
• [4] Mario Gerla,Jack Tzu-Chieh Tsai, Multicluster, mobile, multimedia radio network
• [5] Ossama Younis, Sonia Fahmy, Distributed Clustering in Ad-hoc Sensor Networks: A Hybrid, Energy-Efficient Approach