1. 10th International Conference on Telecommunication, ICT’2003,
Papeete, Tahiti,
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, Presented by: Christer Åhlund, Lund University

2. 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 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 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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