gozar: natfriendly peer sampling with onehop distributed ... · june 6, 2011 gozar: natfriendly...
Post on 08-Jul-2020
2 Views
Preview:
TRANSCRIPT
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 1
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal
Amir H. Payberah – Jim Dowling – Seif Haridi{amir,jdowling,seif}@sics.se
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 2
Introduction
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 3June 6, 2011
Gossipbased Peer Sampling Service
● Gossipbased peer sampling services (PSS) have been widely used in large scale distributed applications.
Information dissemination
Aggregation
Overlay topology management
● A PSS provides a node with a uniform random sample of live nodes from all nodes in the system (partial view).
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 4June 6, 2011
Gossipbased Peer Sampling Protocol (1/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 5June 6, 2011
Gossipbased Peer Sampling Protocol (2/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
n8n7n10n5
n1n6n3n11
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 6June 6, 2011
Gossipbased Peer Sampling Protocol (3/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
n8n7n10n5
n1n6n3n11
shuffle request
n8n7
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 7June 6, 2011
Gossipbased Peer Sampling Protocol (4/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
n8n7n10n5
n1n6n3n11
shuffle response
n1n6
n8n7
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 8June 6, 2011
Gossipbased Peer Sampling Protocol (5/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
n8n7n10n5
n1n6n3n11
n1n6
n8n7
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 9June 6, 2011
Gossipbased Peer Sampling Protocol (6/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
n8n7n10n5
n1n3n6n11
n1n6
n8n7
UpdateState
UpdateState
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 10June 6, 2011
Gossipbased Peer Sampling Protocol (7/7)
n1n2
n3
n4n5
n6n7
n8
n9
n10
n11
n8n7n10n5
n1n3n3n11
n1n6
n8n7
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 11June 6, 2011
Gossipbased Peer Sampling Design Space
● Peer Selection
● View Exchange
● View Mergen1
n2
n3
n4
n6n7
n8
n9
n10
n11
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 12June 6, 2011
Gossipbased Peer Sampling Design Space
● Peer Selection Random
Tail
● View Exchange Push
PushPull
● View Merge Blind
Healer
Swapper
n1n2
n3
n4
n6n7
n8
n9
n10
n11
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 13
Problem Description
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 14June 6, 2011
NAT Environments (1/4)
n1
n2n3
n4
n5
n6
n7
n8
n9
n10
n11
Private node
Public node
shuffle request
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 15June 6, 2011
NAT Environments (1/4)
n1
n2n3
n4
n5
n6
n7
n8
n9
n10
n11
Private node
Public node
shuffle response
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 16June 6, 2011
NAT Environments (1/4)
n1
n2n3
n4
n5
n6
n7
n8
n9
n10
n11
Private node
Public node
shuffle response
UpdateState
UpdateState
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 17June 6, 2011
NAT Environments (1/4)
n1
n2n3
n4
n5
n6
n7
n8
n9
n10
n11
Private node
Public node
shuffle request
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 18June 6, 2011
Impact of NATs on PSS' (1/2)
● Size of the biggest cluster for an increasing percentage of NATs.
[A.M.Kermarrec – ICDCS'09]
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 19June 6, 2011
Impact of NATs on PSS' (2/2)
● Ratio of nonstale references to private nodes.
[A.M.Kermarrec – ICDCS'09]
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 20June 6, 2011
Solutions for Communicating with Private Nodes (1/3)
● Relay communications to the private node using a public relay node.
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 21June 6, 2011
Solutions for Communicating with Private Nodes (2/3)
● Use a NAT holepunching algorithm to establish a direct connection to the private node using a public rendezvous node.
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 22June 6, 2011
Solutions for Communicating with Private Nodes (3/3)
● Route the request to private nodes using chains of existing open connections (of unbounded length).
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 23June 6, 2011
Research Challenges for a NATfriendly PSS
● Assuming distributed relay and rendezvous services, how do nodes discover which public nodes act as partners for the private nodes?
● Is holepunching or relaying preferable for communicating with private nodes?
How much data will be sent over the connection and what are the latency requirements?
● How fairly should the gossiping load be balanced over public versus private nodes?
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 24
Gozar – NAT friendly Peer Sampling Service
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 25June 6, 2011
Design Space
● Peer Selection Rand
Tail
● View Propagation Push
PushPull
● View Selection Blind
Healer
Swapper
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 26June 6, 2011
Design Space
● Peer Selection Rand
Tail
● View Propagation Push
PushPull
● View Selection Blind
Healer
Swapper
Gozar
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 27June 6, 2011
NAT Friendliness in Gozar
● In Gozar, each private node connects to one or more public nodes, called partners that act as a relay or rendezvous server on behalf of the private node.
● A node's descriptor consists of both its own address, its NAT type, and its partners' addresses at the time of descriptor creation.
● When a node wants to gossip with a private node, it uses the partner addresses in its descriptor to communicate with the private node.
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 28June 6, 2011
Partnering (1/10)
Bootstrap servern1n1
n2
n3
n4
n5
...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 29June 6, 2011
Partnering (2/10)
Bootstrap servern1n1
n2
n3
n4
n5
...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 30June 6, 2011
Partnering (3/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 31June 6, 2011
Partnering (4/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
request
request
...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 32June 6, 2011
Partnering (5/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
ACK
NACK
...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 33June 6, 2011
Partnering (6/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 34June 6, 2011
Partnering (7/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
Shuffle exchange
n2, private, n1...
...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 35June 6, 2011
Partnering (8/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
Shuffle exchange
n2, private, n1...
n2, private, n1...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 36June 6, 2011
Partnering (9/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
Shuffle request
n2, private, n1...
n2, private, n1...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 37June 6, 2011
Partnering (10/10)
Bootstrap servern1n1
n2
n3
n4
n5n1, public, nulln4, public, null...
Shuffle response
n2, private, n1...
n2, private, n1...
...
...
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 38June 6, 2011
Relaying or Hole Punching?
● Relaying?
Lower latency message exchange.
• Enables lower gossip cycle periods.
• Necessary in dynamic networks
● Hole punching?
Decreases load on public nodes.
• But not if shuffle messages are small.
● Applications that use the PSS can use partners to holepunch or relay messages to private nodes.
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 39
Experiments
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 40June 6, 2011
Experiment Setup
● Using the Kompics as a simulator platform.
● King dataset is used to model the latencies between nodes.
● 1000 nodes, 80% of nodes are private and 20% are public.
● Compare with Nylon and ARRG.
● Cyclon is used as a baseline.
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 41June 6, 2011
Metrics
● Randomness properties:
Local randomness
Indegree distribution
Clustering coefficient
Avg. path length
● Protocol overhead.
● Fairness and connectivity in catastrophic failure.
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 42June 6, 2011
Randomness
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 43June 6, 2011
Protocol Overhead
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 44June 6, 2011
Fairness and Connectivity in Failure
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 45
Conclusions
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. Payberah 46June 6, 2011
Conclusions
● Gozar is a NATfriendly gossipbased peer sampling service that also provides a distributed NAT traversal service to clients of the PSS.
● Public nodes are leveraged to provide both the relaying and hole punching services.
● Relaying is only used for gossiping to private nodes
lower connection latency
• Enabling a faster gossiping cycle
The messages relayed are small
Gozar: NATfriendly Peer Sampling with OneHop Distributed NAT Traversal – Amir H. PayberahJune 6, 2011 47
top related