From Ad Hoc to ICEBERG: differences in two wireless network environments

1. From Ad Hoc to ICEBERG: differences in two wireless network environments Zhigang Gong gong@cs.umn.edu August 9, 2002 Computer Science and Engineering Department University of Minnesota Wireless Networking Seminar

2. Outline • Ad Hoc • What is ad hoc network? • Why ad hoc network? • What are the interesting research topics? • ICEBERG • What is ICEBERG? • Why study ICEBERG? • How can we take it further?

3. What are Ad Hoc Networks • In Latin, ad hoc means "for this," further meaning "for this purpose only.” • An ad-hoc network is a LAN or other small network, especially one with wireless connections, in which some of the network devices are part of the network only for the duration of a communications session or, in the case of mobile or portable devices, while in some close proximity to the rest of the network.

4. Definition for Mobile Ad-hoc • A "mobile ad hoc network" (MANET) is an autonomous system of mobile routers (and associated hosts) connected by wireless links--the union of which form an arbitrary graph. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet. -------- IETF

5. Characteristics of ad hoc wireless network • Autonomous (no infrastructure !); • Wireless link based; (bandwidth constraint) • Dynamic topology; (Due to movement or entering sleep mode); • Rely on batteries for energy; (Power-constraint) • Limited physical security;

6. Why ad hoc wireless networking? • Technical side: • wireless devices need to be connected; • increased performance/cost ratio on devices • Internet compatible standards-based wireless systems; • Market side: • mobile computing; wearable computing; military applications; disaster recovery; robot data acquisition

7. Research Challenges (I) • MAC layer problems: • Link layer reliability • QoS at MAC layer • Power conservation • Network layer problems: Mobile IP • Routing; • QoS • Power conserving • Multicast

8. Research Challenges (II) • Transport layer problems: (TCP over Ad hoc) • End-to-end reliability? • Congestion control? • QoS? • Application layer: • Security? • QoS? • Inter-layer interactions; • Internetworking with internet;

9. Main problem: Routing • Standard (Mobile) IP needs an infrastructure • Home Agent/Foreign Agent in the fixed network • DNS, routing etc. are not designed for mobility • No infrastructure in Ad hoc networks • Main topic: routing • no default router available • every host (node) should be able to forward packets

10. Routing in an ad-hoc network N1 N1 N2 N3 N2 N3 N4 N4 N5 N5 good link weak link time = t1 time = t2

11. Traditional routing algorithms • Distance Vector • periodic exchange of messages with all physical neighbors that contain information about who can be reached at what distance • selection of the shortest path if several paths available • Link State • periodic notification of all routers about the current state of all physical links • router get a complete picture of the network

12. Problems of traditional routing algorithms • Dynamic of the topology • frequent changes of connections, connection quality, participants • Limited performance of mobile systems • periodic updates of routing tables need energy without contributing to the transmission of user data, sleep modes difficult to realize • limited bandwidth of the system is reduced even more due to the exchange of routing information • Problem: protocols have been designed for fixed networks with infrequent changes and typically assume symmetric links

13. Routing (Unicast) • Table Driven: DSDV, WRP, etc • On-demand Driven: AODV, TORA, DSR, ABR, SSR, …… • Zone Routing Protocol (ZRP)

14. DSDV (Destination Sequenced Distance Vector) • Expansion of distance vector routing • Sequence numbers for all routing updates • assures in-order execution of all updates • avoids loops and inconsistencies • Decrease of update frequency • store time between first and best announcement of a path • inhibit update if it seems to be unstable (based on the stored time values)

15. Dynamic source routing (DSR) • Split routing into discovering a path and maintaining a path • Discover a path • only if a path for sending packets to a certain destination is needed and no path is currently available • Maintaining a path • only while the path is in use one has to make sure that it can be used continuously • No periodic updates needed!

16. Dynamic Source Routing – Internet-Draft • Characteristics: • On-demand • Unidirectional links and asymmetric routes are supported • Route Discovery: • S-D route is included in the header of each packet. • Nodes forwarding or overhearing data packets may cache multiple routes for any D for future use (uni-directional?) • Route Maintenance: on-demand • Link failure detection: MAC layer (802.11) or Passive ACK or clear request for ACK • Link ERR is propagated to source • Use an cached new route or rediscover

17. Dynamic Load-Aware Routing • On-demand, backward learning • S floods REQ, D choose route by-- Total buffered packets, Average buffered packets, or Least number of congested routers • D detects over-loaded route dynamically and initiates route-setup procedure to S. • Load information in I is piggybacked periodically on data packets • When link failure, the upstream I sends ERR to S and removes its entry. S initiates new route setup procedure. • I does not reply REP even it knows a route to D

18. Mitigating routing misbehavior • It is impossible to build a perfect network • Routing denial of service • Unexpected events, bugs, etc. • Incorporate tools within the network to detect and report on misbehavior • Route only through trusted nodes • Requires a trust relationship • Requires key distribution • Trusted nodes may still be overloaded or broken or compromised • Untrusted nodes might perform well • Detect and isolate misbehaving nodes • Watchdog detects the nodes • Pathrateravoids routing packets through these nodes

19. Routing (Multicast) • Multicast is still a hot topic even in Internet; • In Ad Hoc, besides of those problems in traditional Internet, such as congestion control, routing for multicast is another big problem;

20. Other researches on Routing • QoS support routing; • Power conserving routing;

21. ICEBERG • http://iceberg.cs.berkeley.edu/ • ICEBERG: Internet-based core for CEllular networks BEyond the thiRd Generation • Internet-based integration of telephony and data services spanning diverse access networks • Leverage Internet’s low cost of entry for service creation, provision, deployment and integration

22. Why ICEBERG • 3G+ will enable many communication devices and networks – diversity • Mobility for transparent information access • New applications: audio, video, multimedia

23. Design Goals • Potentially Any Network Services (PANS): • Network and device independent • Personal Mobility: • person as communication endpoint; requires a single identity for an individual - iUID • Service Mobility: • seamless mobility across different devices in the middle of a service session • Easy Service Creation and Customization • Scalability, Availability and Fault Tolerance • Operation in the Wide Area • Security, Authentication and Privacy

24. PSTN GSM Pager A NY iPOP IAP IAP IAP IAP IAP SF iPOP IAP B NY iPOP CA SF iPOP PR PAC APC NMS ICEBERG Architecture Overview Access Network Plane ICEBERG Network Plane Clearing House ISP Plane ISP1 ISP2 ISP3

25. ICEBERG Components • ICEBERG Access Point (IAP): • A gateway serves as a bridge • Call Agent (CA): • call setup and control • Name Mapping Service (NMS): • mapping between communication endpoint and the iUID • Preference Registry (PR): • stores user profile • Personal Activity Coordinator (PAC): • tracks dynamic info of a person that is of her interest • Automatic Path Creation Service (APC): • establishes and manipulates data flow

26. iPOP on Cluster Computing Platforms • Ninja Base and Active Service Platform (AS1) • Clusters of commodity PCs interconnected by a high-speed SAN, acting as a single L-S computer • mask away cluster management problems • Load balancing, availability, failure management • Ninja: highly available service initiation • Redirector stub • Good for long running services such as web servers • AS1: fault tolerant service session • Client heartbeat with session state • Good for session-based services such as video conferencing

27. 4 Call Agent Call Agent 7 3 5 8 1 An Illustration Bob Alice 2 PR NMS PR NMS IAP IAP Clearing House

28. What’s their difference? • ICEBERG is an integrated service architecture to link any digital network with the Internet. • Ad Hoc is in the wireless network domain. • Put them together, some amazing application may be available.