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DVE over Ad Hoc Network. 黃仁竑 中正大學資工系 / 通訊系. Outline. Introduction problems Addressing method Routing unicast, multicast DVE architecture Conclusion. Main challenges. Characteristics of traditional DVE Client/Server Model Network bandwidth Distributed interaction Message type

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dve over ad hoc network

DVE over Ad Hoc Network

黃仁竑

中正大學資工系/通訊系

outline
Outline
  • Introduction
    • problems
  • Addressing method
  • Routing
    • unicast, multicast
  • DVE architecture
  • Conclusion
main challenges
Main challenges
  • Characteristics of traditional DVE
    • Client/Server Model
    • Network bandwidth
    • Distributed interaction
    • Message type
    • Scalability
    • Resource management
    • Network topology
main challenges cont
Main Challenges (cont.)
  • Characteristics of Ad Hoc Network
    • Lack of infrastructure
    • Low bandwidth
    • Signals are easy to be obstructed
    • Mobility
    • Low reliability
    • Client/Server architecture is not suitable
project statements
Project Statements
  • Study network virtual environment in Ad Hoc P2P networks
  • Approaches
    • Layered design
      • Similar to OSI/ISO 7 layer (or DVE over TCP over IP)
      • Separate DVE, P2P, Ad Hoc
    • Simulated scenario
      • Consider physical formation of Ad Hoc network
      • DVE is designed with physical Ad Hoc network in mind
our solutions and goals
Our Solutions and Goals
  • Constructing a P2P infrastructure on the Ad Hoc Network
    • Routing, mobility (dynamic re-addressing)
  • Building a networked virtual environment over P2P
issues p2p over manet
Issues P2P over MANET
  • Overlay topology
    • Self-organizing, self-addressing
  • Routing
    • Unicast, multicast
  • Mobility
    • Fault tolerant
overlay topology
Overlay Topology

Self-organizingSelf-addressing

addressing issue 2
Addressing Issue(2)
  • Example1:

1.0

1.0

1.0

1.0

1.0

Reply to join with IP

Request to join

1.1

Reply ack

(4)

(5)

(1)

(2)

(3)

addressing issue 3
Addressing Issue(3)
  • Example2:

1.0

1.0

1.0

1.0

1.0

Reply with IP

Reply ack

1.1

1.1

Request to join

1.1

1.1

1.1

1.2

Reply with IP

(1)

(2)

(3)

(4)

(5)

policy to choose a parent node
Policy to choose a parent node
  • For low mobility environment
    • Define a threshold of signal strength
    • Choose parent that has shortest logical IP and stronger signal strength than the threshold
  • Logical IP changes slowly
    • Less maintenance overhead
other possible policies
Other Possible Policies
  • Most power capacity
  • Strongest signal
  • Lowest mobility
routing
Routing
  • Default routing
    • Traverse the tree up to the nearest common ancestor and then down to the destination
  • Enhancement: Cache
    • Take advantage of broadcast
    • Cache two-hop away neighbors
    • Longest Prefix Match
take advantage of broadcast
Take advantage of broadcast
  • Node 1.1.1.2 is closer to 1.1.2.1
  • Node 1.1.1.2 can detect that 1.1.1.1 is sending packets to 1.1.2.1 because of broadcasting
mobility
Mobility
  • Nodes may select a new node as its parent:
    • Signal strength is weaker than some threshold
    • Signal range can’t reach its original parent
multicast
Multicast
  • Members join
  • Members leave
  • Packet forwarding
membership management
Membership management
  • Join
    • Take advantage of the tree architecture
  • Leave
    • Similar to join
slide23
Join

1

1.1

1.2

1.1.1

1.1.2

M

1.2.1

1.1.1.1

1.1.2.1

P

1.2.1.2

rules of join
Rules of join
  • Requesting node P sends join message to its parent M
  • If M is already in the group, discard the message
  • Otherwise, the message will be forwarded to the parent of M up to the root
forwarding
Forwarding
  • Packet format
    • <M,S,I>
    • M: multicast address
    • S: source address
    • I: intermediate address
forward cont
Forward (cont.)
  • For some node A
    • Up
      • I is a child of A
      • I exactly matches the prefix of S
    • Down
      • I is the parent of A
      • S is not any descendant of A
      • Some descendants of A are members of M
    • If A is the root of the tree
      • If other branches have members of M, forward the packet
issues of dve in ad hoc network
Issues of DVE in Ad Hoc Network
  • Unworkable solutions
    • Static server
    • Direct P2P message exchange (flood of messages)
  • Proposed solution
    • AOI+Multicast
aoi multicast
AOI + Multicast
  • Entities (or avatar) only interested in receiving information from entities within AOI
  • Entities send messages to or receive them from their AOIs, corresponding to the region in which they are acting
  • Map each region (cell) into a multicast group
dve software architecture
DVE software architecture
  • Multicasting
    • Fully distributed (no server)
    • Scalable
  • AOIM (area of interest manager)
    • Divide the virtual world into several cells
    • Assign distinct multicast channels to each cell
slide30
AOIM
  • Entities send messages to AOI (its cell and neighbor cells) via multicast channels
  • Entities listen to the multicast channel of its cell only
  • No centralized servers are needed
dve software architecture1
DVE software architecture

Control message from user

IO

Message queue

render

AOIM

Message queue

Message queue

Net

leader of the cell
Leader of the cell
  • Leader maintains status of entities in the cell
  • When a new entity enters the cell, it requests information of other entities from the leader
  • The state of the new joined cell can be initialized
election of cell leader
Election of cell leader
  • An entity enter a new cell
    • It sends a message to find the leader
    • If there is no response, it becomes the leader
  • When an entity leave a cell
    • It sends a message to tell other entities
    • Other entities then send their MAC address to the cell, and the entity with largest MAC address will be the new leader
conclusion
Conclusion
  • P2P over MANET
    • Tree structured overlay topology
    • Self-addressing, self-organizing
    • Unicast and multicast routing
  • DVE
    • Multicast + AOI
  • What can be discussed in the future?
    • Connectivity, fast mobility
    • Commercial products?