10th International Conference on Telecommunication, ICT’2003, Papeete, Tahiti, 25.02.2003 Name Resolution in On-demand MANETs - and over External IP Networks Engelstad, P.E., Thanh, D.V., Jønvik, T.E. University of Oslo (UniK) / Telenor R&D, 1331 Fornebu, Norway {Paal.Engelstad, Thanh-van.Do, Tore-Erling.Jonvik}@telenor.com http://folk.uio.no/paalee/ Presented by: Christer Åhlund, Lund University

Background - I Paper addresses lack of a distributed name resolution mechanism for on-demand MANETs Users cannot easily use common applications (i.e. those for e-mail and web-browsing) without a method for name resolution This paper proposes a mechanism for name resolution in on-demand MANETs: It cooperates with the Reactive Routing protocol It is on-demand It interoperates with DNS over External IP Networks It is transparent to user applications Paper addresses lack of a distributed name resolution mechanism for on-demand MANETs: - IP addresses (32 bits or 128 bits) are two difficult to remember - Users require that a Name Resolver resolves a name to an IP address on behalf of the applications they are using. Users cannot use common applications (i.e. those for e-mail and web-browsing) without a method for name resolution This paper proposes a mechanism for name resolution in on-demand MANETs: - It cooperates with the Reactive Routing protocol - Must streamline to get efficient operation - It is on-demand - Only names that are resolved consume network bandwidth - I.e. it scales to a large number of available (unresolved) names - It interoperates with DNS over External IP Networks - ... to reduce the total amount of consumed network bandwidth - It is transparent to user applications - Users should be able to use the same applications that they use on fixed internet for communication on the MANET - For communication with other MANET nodes - For communication to Internet nodes over the external IP network 27. mai. 2019 Telenor

Background - II Related work Reactive Routing Protocols (e.g. AODV, DSR, TORA, ...) Multicast DNS: For on-link zero-configuration Defines ‘.local.’ domain Mechanisms to handle multiple requests and multiple responses Service Discovery for on-demand MANETs Actually submitted as Internet-Draft after this presented article was submitted to ICT’2003 Proposes similar mechanisms, but for service discovery Based on SLPv2 message formats See paper for references... 27. mai. 2019 Telenor

Basic principles and mechanisms (Problem: 3 Broadcasts) Name Requestor broadcasts a name resolution request Name Owner Broadcasts a reply (because no return route has been formed). Name Requestor broadcasts a name resolution request. Name Owner Broadcasts a reply (because no return route has been formed). Name Requestor broadcasts a RREQ to find a route to the resolved IP-address (because no forward route has been formed). Name Requestor broadcasts a name resolution request NR NS Name Requestor Owner 27. mai. 2019 Telenor

Basic principles and mechanisms (Solution: 1 Broadcast) Name Requestor broadcasts a name resolution request, carried by a RREQ routing header, which forms a return unicast route. Name Owner unicasts a reply back along the return route. It is carried back by a RREP routing header, which forms a forward route. Name Requestor broadcasts a name resolution request, carried by a RREQ routing header, which forms a return unicast route. Name Owner unicasts a reply back along the return route. It is carried back by a RREP routing header, which forms a forward route. Name Requestor may contact the resolved IP address along the forward route. Name Requestor broadcasts a name resolution request, carried by a RREQ routing header, which forms a return unicast route. NR NS Name Requestor Owner 27. mai. 2019 Telenor

Transparency for Applications Applications should communicate through the same API, whether on an Internet host or on a MANET node Transparent to Name Resolver Lower layer translates between UDP and a bandwidth-efficient message format for wireless transmission (3 upper figures to the left) Or the Name Resolver is MANET aware Forms manages appropriate on-air requests and replies without help from undelying module (Figure at bottom) 27. mai. 2019 Telenor

Interworking with External IP Networks A MANET gateway is a MANET node that is also a router or host on an external IP network We proposed to use a MANET Gateway as a DNS proxy Most Internet hosts implement a DNS resolver Resolves IP addresses on-demand by a conventional DNS server on external network, and injects the result into the MANET. Nodes can acquire global connectivity only when required Option: Nodes with global connectivity may use conventional DNS server, e.g. if MANET-local name resolution fails. 27. mai. 2019 Telenor

Additional mechanisms required Response Selection Prioritize responses of IP-addresses present on the MANET Prioritize first hand information from name-owner over second-hand cached information Prioritize resolved IP addresses to which the best route exists Marking IP addresses resolved over External IP Networks... A node might have to handle such responses differently (e.g. not prioritize them – above) Duplicate Response Suppression A mechanism that allows some responses being lost on the air, but suppression of unnecessary many responses to the same request 27. mai. 2019 Telenor

Different strategies for storage of name-to-address information - I Partially Centralized Approach: Use Name Coordinators Name Owners will first have to find and register with a NC Increases complexity Have to synchronize information Avoid false positive and false negative lookups Might have to maintain valid routes to avoid additional broadcast when binding to resolved IP address This adds a proactive element to a scenario calling for a reactive solution. 27. mai. 2019 Telenor

Different strategies for storage of name-to-address information - II Fully Distributed Approach All ’Name Owners’ must run their own Name Server process and help resolving their own name. Hybrid Approach Benefits of using a centralized server is unclear, but might be implemented on a IGW, in scenarios where IGWs are not mobile on the external network. Caching of Intermediate Nodes Intermediate nodes caches name-to-address mappings appearing in NREPs that they are forwarding. Only respond when route is valid Possible reply implosion? Benefits are unclear. 27. mai. 2019 Telenor

Wrap-up A mechanism for name resolution in on-demand MANETs is proposed and detailed... Internet-Draft draft-engelstad-manet-nameresolution-00.txt Submitted to IETF Produced as a by-product of the presented paper Contains message formats and other details of the presented scheme Thank you for your attention! 27. mai. 2019 Telenor