Ad Hoc Networks Routing (2/2)

1. Ad Hoc Networks Routing(2/2) Instructor: Carlos Pomalaza-RáezFall 2003University of Oulu, Finland

2. Zone Routing Protocol (ZRP) • Hybrid reactive/proactive protocol • Proactive procedure only to the nodes within a routine zone of radius ρ • Reactive procedure to nodes beyond the routing zone by querying only a subset of the network nodes Routing zone of radius = 2 hops Neighbor node S Peripheral node M. R. Pearlman, and Z. J. Haas, “Determining the Optimal Configuration for the Zone Routing Protocol,” IEEE JSAC, Aug. 1999, vol. 17, no. 8, pp. 1395-1414

3. ZRP - Routing Zones • A collection of nodes which are within the zone radius of another node • Zone radius of a node is defined in terms of number of hops from that node • The transmission power as well as the propagation conditions and receiver sensitivity determines the set of neighbors • Each node has its own routing zone • Routing zones of different nodes may overlap • Each node maintains routing information to all nodes within its own routing zone • The nodes uses a proactive mechanism to learn about the topology of its routing zone, this mechanism is called Intrazone Routing Protocol (IARP)

4. ZRP – Interzone Routine • The Interzone Routing Protocol (IERP) is responsible for reactively discovering routes to destinations located beyond a node’s routing zone • The Bordercast Resolution Protocol (BRP) allows the node to send messages only to its peripheral nodes • Efficient querying of specific nodes rather than flooding the whole network • Bordercasting can be implemented using efficient multicast techniques • A single route query returns multiple route replies, which can be used to determine the best route based on relative quality • Because the routing zones overlap, a node can be a member of many routing zones • It is important to have a mechanism to detect duplicate route queries and squelch excessive control traffic

5. ZRP – IERP (example) G E H F C B D S G • Source S needs to send a packet to destination D • S checks whether D is within its routing zone. If yes, S knows a path to D • If not S bordercasts a query to its peripheral nodes (C, G, and H) • These nodes, after verifying that D is not within their routing zones, bordercast the query to their peripheral nodes • B, a peripheral node of H, recognizes D as being in its routing zone and responds to the query indicating the path S→H →B →D

6. ZRP - Guiding the Search in Desirable Directions Desired search direction To minimize route query traffic a procedure is needed to steer the query packets outwards from the source’s routing zone and away from each other. Desired search direction source This problem is addressed through the following mechanisms: Desired search direction • Loop-back Termination (LT) • Query Detection (QD1/QD2) • Early Termination (ET) • Selective Bordercasting (SBC) Desired search direction Desired search direction

7. ZRP – Query Control Mechanisms Loop-back TerminationThe query is terminated when the accumulated route (excluding the previous node) contains the host which lies in routing zone, e.g., route = {S→A→B→C} C terminates the query, because S is in the C’s routing zone. A S B C Earlier query Early TerminationWhen a thread penetrate into previously covered areas, the excess traffic can be terminated by extending the ability of the intermediate nodes, e.g. intermediate node A passes along a query to B. B terminates the thread because a different thread of the same query has been detected earlier. C S B Later query A

8. ZRP – Query Control Mechanisms Query Detection • Only the node that bordercasts a route request is aware that its zone is covered by the query • When the peripheral nodes continue to bordercast to their peripheral nodes, the query may be relayed through the same nodes again • BRP provides two query detection methods, QD1 and QD2, to notify the remaining nodes through some form of eavesdropping without incurring additional control traffic QD1 QD2 E D C S A B QD1 QD1 - Allows intermediate nodes (which relay queries to the edge of the routing zone) to detect queries, e.g., A and C can detect passing route request packet and record that S’s routing zone has been queried QD2 - In single channel networks, it is possible for queries to be detected by any node within range of a query transmitting node, e.g., E may be able to receive C’s transmission and record the query information

9. ZRP – Query Control Mechanisms • Selective Bordercasting (SBC) • Rather than bordercast queries to all peripheral nodes, the same coverage can be provided by bordercasting to a chosen subset of peripheral nodes • Requires IARP to provide network topology information for an extended zone that is twice the radius of the routing zone • A node will first determine the subset of other peripheral nodes covered by its assigned inner peripheral nodes • The node will then bordercast to this subset of assigned inner peripheral nodes which forms the minimal partitioning set of the outer peripheral nodes X Y H G Z B C A F S B is redundant • S’s inner peripheral nodes are A, B and C • Its outer peripheral nodes are F, G, H, X, Y and Z • Two inner peripheral nodes of B (H and X) are also inner peripheral nodes of A and C • S can then choose to eliminate B from its list of bordercast recipients since A can provide coverage to H and C can cover X

10. ZRP - Architecture IARP IERP The Zone Routing Protocol NETWORK Layer Inter-process communications Packet Flow MAC Layer (including NDP) • Route updates are triggered by the MAC-level Neighbor Discovery Protocol (NDP) • IARP is notified when a link to a neighbor is established or broken • IERP reactively acquires routes to nodes beyond the routing zone • IERP forwards queries to its peripheral nodes (BRP) keeping track of the peripheral nodes through the routing topology information provided by IARP

11. ZRP - Summary • ZRP combines two completely different protocols, one proactive and the other reactive, into a single protocol based on clustering of nodes into routing zones • Proactive IARP maintains routing tables within a routing zone • Reactive IERP performs route discovery outside the zone • ZRP can perform worse than flooding without proper query control mechanisms. • Query Detection, Early Termination, and Loop-back Termination provide significant improvements compared with purely reactive and purely proactive schemes • Use of Bordercasting reduces significantly the amount of inter-zone control traffic

12. Mobile Node Internet CorrespondentNode Mobile IP The Internet Engineering Task Force (IETF) designed Mobile IPv4 in 1996 to facilitate IP-based communications to mobile wireless users HomeNetwork Home Agent Foreign Agent VisitedNetwork It acquires a temporary care-of-address from the network’s foreign agent And informs an agent on its home network of this address Packets that a correspondent node sends to the mobile are sent to its permanent address in the home network When a mobile node moves onto a visited network The home agent forwards the packet to the care of address The mobile agent sends replies directly to the correspondent node

13. Mobile Node Internet CorrespondentNode Mobile IPv6 (2003) HomeNetwork Home Agent binding acknowledgment binding update care-of-address VisitedNetwork The mobile node informs the correspondent node of thecare-of-address After which the mobile and the correspondent node can exchange packets directly The home agent replies with a binding acknowledgment It constructs a care-of-address and sends a binding update to its home agent Initially the correspondent node communicates with mobile node via the mobile’s home agent When a node moves to a visited network

14. Basic Operation of IPv6 • A mobile node can always be addressed at its home address, whether it is currently at “home” or away • When a mobile node is away from home it is also addressable at one or more care-of-addresses • The mobile acquire its care-of-address via a stateless or stateful auto-configuration mechanism • The mobile can accept packets from several care-of-addresses, such as when it is moving • The association between a mobile’s home address and care-of-address is known as binding • The mobile performs a binding registration by sending a binding update message to its home agent • The home agent replies to the mobile node with a binding acknowledgment message • A mobile can provide information about their current location to correspondent nodes

15. IPv6 Network Architecture Internet Router Router Access Point Access Point Access Point Access Point Access Point Access Point When a mobile node moves to a new point of attachment on another subnet it needs to acquire a new valid care-of-address in the visiting subnet and register it with its home agent and correspondents

16. Mobile IPv6 Handover Procedure • A mobile node detects that it has moved to a new subnet by analyzing the router advertisement periodically sent by the access router • The mobile node performs a duplication address detection (DAD) procedure to verify the uniqueness of its link-local address on the new subnet • Once it has obtained a new care-of-address it may perform a DAD for it • Once the new care-of-address is done the mobile node updates the binding cache of its home agent and correspondents by sending a binding update • In some cases a mobile node can be reached through multiple care-of-addresses if it is within the range of multiple access points • One of these care-of-addresses must be the primary care-of-address for a default access router (AR) • When the default AR becomes unreachable, the mobile node can use a new default AR for which it already has a care-of-address

17. Mobile Node Router-Assisted Smooth Handover • The mobile node moves to another subnet CN (2) Mobile sends a Binding Update to a Home Agent on previous network (4) (5) (3) Home Agent returns a Binding Acknowledgement IPv6 router (4) IPv6 router (3) (4) Home Agent tunnels packets to Mobile (2) (5) Mobile sends a Binding Update to Correspondent (1)

18. Mobile Node Hierarchical Mobile IPv6 • Objective is to minimize the amount of signaling • Internet is divided into regions each with a mobility anchor point with a publicly routable IP address • Within each region, at a level below the mobility anchor point, there are Access Routers (AR) to which the mobile connects as it moves within the region • When a mobile enters a domain it makes a regional registration to advertise to its home agent and correspondents its new raw location Mobility Anchor Point Internet Home agent Access routers Administrative Domain N. Montavont and T. Noël, “Handover Management for Mobile Nodes in IPv6 Networks,” IEEE Communications Magazine, August 2002, pp. 38-43.

19. Modes of Hierarchical MIPv6 • Basic Mode • The mobile has two addresses: a regional care-of-address based on the mobility anchor point prefix and an on-link care-of address based on the current AR prefix • The mobility anchor points acts as home agent: it intercepts the packets destined to a regional care-of-address and tunnels them to the corresponding on-link care of address • Extended Mode • The regional care-of-address is one of the mobility anchor point address • This anchor points keeps a binding table with the current on-link care-of-address of a mobile matched with the mobile home address • When the anchor point gets a packet destined to a mobile, it de-tunnels and re-tunnels it to the on-link care-of-address

20. Fast Handover Protocol • Extension of Mobile IPv6 that allows an AR to anticipate a Layer 3 handover • The anticipation is based on a Layer 2 trigger mechanism • This mechanism allows for the start of a L3 handover before the L2 handover ends • The L2 triggers used are: • Link Up – the mobile has established a connection with an access point • Link Down – the mobile has lost connection with an access point • L2 Handover Star – the mobile has started an L2 handover • Fast Handover uses these L2 triggers in two methods • Anticipated handover • Tunnel based handover

21. Mobile Node FHP: Anticipated Handover Address validation Validation request Old access router New access router Forwarding of the triggers Confirmation L2 triggers Access point Access point New care-of-address Confirmation