Address Auto-configuration in Mobile Ad Hoc Networks Current Approaches and Future Directions

Date： 2005 / 1 / 20

Speaker： Xu Jia-Hao

Advisor： Ke Kai-Wei

Outline

Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

Introduction

Mobile ad hoc networks are infrastructureless self-organizing wireless networks.

Before proper routing of data packets in a network is possible, all nodes need to be configured with unique addresses.

Preconfiguration is not always possible, so that, an autoconfiguration protocol is required.

Introduction (Cont.)

The main task of an address autoconfiguration protocol is to manage the resource address space.

Allocate a unique address to an unconfigured node and deallocate when it leaving the network.

A major challenge is network partitioning and merging.

Introduction (Cont.)

All nodes need to confirm their own address is uniqueness within a single network partition.

Autoconfiguration protocols for conventional networks can be classified in protocols utilizing either stateless or stateful approaches.

Stateful Approach

Assume the existence of a central entity to assign unique addresses to unconfigured nodes and to keep state information about already assigned addresses in an address allocation table.

An example is DHCP (Dynamic Host Configuration Protocol).

Stateless Approach

Allow the nodes to select an address by themselves and verify its uniqueness in a distributed manner with the so-called duplicated address detection (DAD).

The DAD is performed by broadcasting a special ARP probe for the selected address.

Outline

Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

Stateful protocols That can be classified according to the way th

ey maintain the address allocation table. Three major approaches：

Centralized maintenance of the allocation table. Distributed maintenance of a common allocation t

able. Distributed maintenance of multiple disjoint allocat

ion tables. Selects and assigns an address as the initiat

or and the node that requests and address as the requester.

Centralized maintenance of the allocation table

Distributed maintenance of a common allocation table There are three protocols using distributed co

mmon allocation table： MANETconf Boleng’s protocol Prophet allocation protocol

MANETconf Join node j (the requester)：

j send neighbor_query

if no reply is received

assign an address to itself

else

initiator flood an initiator_request contain address

if the address isn’t be used

reply initiator_response to the initiator (so and others)

else (negative reply)

repeat the allocation process with another address

initiator flood address_announce to every node

Distributed maintenance of a common allocation table (Cont.)

Distributed maintenance of multiple disjoint allocation tables The basic idea is to split the allocation table

among all nodes and use buddy systems for efficient table mergers.

The initiator assigns half of its allocation table to the requester and the new node itself can autonomously assign addresses.

Distributed maintenance of multiple disjoint allocation tables (Cont.)

Outline

Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

Stateless Approaches

They do not maintain any allocation table. Instead, an unconfigured node self-assigns an address chosen randomly or based on a hardware ID.

The uniqueness of the address is verified by a DAD procedure after a network merger or permanently performed.

Stateless Approaches (Cont.)

There are three major approaches： Query-based DAD

-- To query all nodes Weak DAD

-- Address & Key Passive DAD

-- Based on protocol events

Outline

Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

Hybrid Approaches

Hybrid protocols combine elements of both stateful and stateless approaches.

There are two kinds of protocols： HCQA ( Hybrid Centralized Query-Based Autocon

figuration ) PACMAN ( Passive Autoconfiguration for Mobile

Ad Hoc Networks )

HCQA

It utilizes QDAD together with a centrally maintained allocation table.

A node selects an address by itself and verifies its uniqueness with the QDAD.

If the DAD is successful, it configures the address and registers with a dynamically elected address authority (AA), which inserts the new address in its allocation table.

PACMAN

It combines PDAD with a distributed maintenance of a common allocation table.

The nodes passively collect information about already assigned addresses in the network from routing protocol traffic.

Outline

Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

Conclusion

A centrally maintained allocation table has fewer problems with inconsistent states, but requires a dynamic leader election algorithm.

The most important component of stateless approaches is DAD.

Reference

Address Auto-configuration in Mobile Ad Hoc Networks: Current Approaches and Future Directions, IEEE Network Magazine, K. Weniger, M. Zitterbart, Vol 18, No. 4, pp. 6-11, 2004.

Problem of partition merged

Address conflicts

The resolution of a conflict requires at least one node to acquire a new address