1. 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

2. Outline Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

3. 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.

4. 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.

5. 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.

6. 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).

7. 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.

8. Outline Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

9. Stateful protocols That can be classified according to the way they maintain the address allocation table. Three major approaches ：  Centralized maintenance of the allocation table.  Distributed maintenance of a common allocation table.  Distributed maintenance of multiple disjoint allocation tables. Selects and assigns an address as the initiator and the node that requests and address as the requester.

10. Centralized maintenance of the allocation table

11. Distributed maintenance of a common allocation table There are three protocols using distributed common allocation table ：  MANETconf  Boleng’s protocol  Prophet allocation protocol

12. 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

13. Distributed maintenance of a common allocation table (Cont.)

14. 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.

15. Distributed maintenance of multiple disjoint allocation tables (Cont.)

16. Outline Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

17. 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.

18. 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

19. Outline Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

20. Hybrid Approaches Hybrid protocols combine elements of both stateful and stateless approaches. There are two kinds of protocols ：  HCQA ( Hybrid Centralized Query-Based Autoconfiguration )  PACMAN ( Passive Autoconfiguration for Mobile Ad Hoc Networks )

21. 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.

22. 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.

23. Outline Introduction Stateful protocols Stateless protocols Hybrid approaches Conclusion Reference

24. 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.

25. 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.

26. Problem of partition merged Address conflicts The resolution of a conflict requires at least one node to acquire a new address