Autoconfiguration Technologies in IPv6 Mobile Ad Hoc Networks

1. Autoconfiguration Technologies in IPv6 Mobile Ad Hoc Networks APAN2003 Jaehoon Jeong, ETRIpaul@etri.re.krhttp://www.adhoc.6ants.net/~paul

2. Contents • Introduction • Unicast Address Autoconfiguration • Multicast Address Allocation • Multicast DNS • Service Discovery • Protocol Stack supporting MANET Autoconfiguration • Conclusion • References

3. Introduction • Mobile Ad Hoc Network (MANET) • MANET has dynamically changing network topology. • MANET partition and mergence may happen. • In MANET, there are many points to consider unlike the Internet. • There is no network administrator. • The current Internet services, such as address autoconfigation and DNS, are difficult to adopt. • So, Auto-configuration is necessary in MANET!!

4. MANET Auto-configuration • Unicast Address Autoconfiguration • Multicast Address Allocation • Multicast DNS • Service Discovery Unicast Address Autoconfiguration MANETAutoconfiguration Service Discovery Multicast DNS Multicast Address Allocation

5. Unicast Address Autoconfiguration

6. Introduction • Configuration of Unicast Address in Network Interface • Precedent step for IP networking • Methods of IP address configuration in network interface • Manual configuration • Automatic configuration • Consideration of IP address configuration • A unique address should be assigned. • Automatic configuration is needed for user’s convenience. • Addressing in MANET • Each mobile node is necessary to autoconfigure its IP address through DAD. • A arbitrary address is selected. • The uniqueness of the address is verified though Duplicate Address Detection (DAD).

7. Strong DAD • Definition • Ai(t) : Address assigned to node i at time t. • For each address a != undefined, Sa(t) = {j | Aj(t) = a}. • Condition of Strong DAD • Within a finite bounded time interval after t, at least one node in Sa(t) will detect that |Sa(t)| > 1.

8. 1st Try of Host A • MAC Address - a9:bb:cc:dd:ee:ff • IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff MANET Prefix EUI-64 • 2nd Try of Host A • 64-bit Random Number – 1111:2222:3333:4444 • IPv6 Address - fec0:0:0:ffff:1111:2222:3333:4444 Random Number Example of Strong DAD • MAC & IPv6 Address of Host C • MAC Address – a9:bb:cc:dd:ee:ff • IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff Host C Host B Host A NA message NS message Router Wireless Link Where NS : Neighbor Solicitation, NA : Neighbor Advertisement

9. Procedure of Strong DAD Generation of 32-bit Random Numberand 64-bit Random Number Generation of Temporary address withMANET_INIT_PREFIX and 32-bit Number • MANET_INIT_PREFIX • fec0:0:0:ffff::/96 • MANET_PREFIX • fec0:0:0:ffff::/64 Generation of Tentative address with MANET_PREFIX and 64-bit Number Transmission of Extended NS message This iteration is performed by predefined retry-number. Was any extended NA message received from any other node? YES NO Generation of 64-bitRandom Number Reconfiguration of Unicast address in NIC

10. Problem of Strong DAD - 1/2 IP address = a A F B C G H E K D IP address = a

11. Problem of Strong DAD – 2/2 IP address = a A F B C G H E K D IP address = a

12. Conclusion for Strong DAD • Simple Observation • If partitions can occur for unbounded intervals of time, then strong DAD is impossible. • Limitation of Charles E. Perkins’s DAD • When partitions merge, addresses of all nodes must be checked for duplicates. • This DAD does not indicate how merging of partitions should be detected. • This does not suggest how the congestion caused by DAD messages may be reduced.

13. Weak DAD • Requirements • Correct Delivery • Packets meant for one node must not be routed to another node, even if the two nodes have chosen the same address. • Relaxed DAD • It does not require detection of all duplicate addresses. • The duplication of addresses can not be detected in partitioned networks.

14. Definition • Assumption • A packet sent by node X at time t to destination address a be delivered to node Y that has chosen address a. • Condition • After time t, packets from node X with destination address a are not delivered to any node other than node Y.

15. Design Goals • Address size cannot be made arbitrarily large. • MAC address cannot be embedded in the IP address. • IP header format should not be modified. • It is wanted to add new options to the IP header. • Contents of routing-related control packets may be modified to include information pertinent to DAD. • E.g., Link state updates, Route request / reply. • No assumptions should be made about protocol layers above the network layer.

16. Main Idea • Key is used for the purpose of detecting duplicate IP addresses. • The key is not embedded in the IP address itself. • Generation of Key • MAC Address • When MAC address of an interface is guaranteed to be unique. • Random Number • A sufficiently large number of bits of making the probability of key conflict acceptably small • Number derived from some other information • E.g., Manufacture’s name and device serial number

17. Link State Routing with Strong DAD Routing table at node D A B C E Link state packet transmitted by D D

18. Link State Routing with Weak DAD Routing table at node D A B C E Link state packet transmitted by D D

19. Resolution of Address Conflict by Weak DAD (IP address, Key) = (a, K_A) A F B C G H E DuplicationAdvertisement K D (IP address, Key) = (a, K_K) E detects the duplication of address a with key information (IP address, Key) = (b, K_K)

20. Hybid DAD • Hybid DAD • Combination of Strong DAD and (Enhanced) Weak DAD • Strong DAD detects duplicate address within a single connected partition. • Weak DAD processes the address conflict by MANET’s partition and mergence. • Hybrid DAD Scheme • It may detect some duplicate addresses sooner than using weak DAD alone. • The use of weak DAD makes it robust to partitions and large message delays in Strong DAD.

21. Phases of Hybid DAD • 1st Phase • By Strong DAD • Time-based DAD • It is performed in the stage for IPv6 address to be configured in network interface. • 2nd Phase • By Weak DAD • It is performed during the routing process. • Router discovery in reactive Ad Hoc routing protocols, such as DSR and AODV. • Routing information exchange in proactive Ad Hoc routing protocols, such as OLSR and TBRPF.

22. Conclusion for Unicast Address Autoconfiguration • Requirements of Ad Hoc DAD • Correct Delivery • Packets meant for one node must not be routed to another node, even if the two nodes have chosen the same address. • Relaxed DAD • It does not require detection of all duplicate addresses. • The duplication of addresses can not be detected in partitioned networks. • Guarantee of Upper-layer session • Under the address change by DAD, the upper-layer session, such as TCP session, should be guaranteed to continue.

23. Multicast Address Allocation

24. Multicast Address Allocation • Role • It allocates a unique IPv6 multicast address to a session without address allocation server. • Address Format • IPv6 multicast (a) is generated on the basis of Interface IDof IPv6 unicast address (b).

25. Request ofMulticast Address Allocation Generation of Unused Group ID Generation of a Multicast Address Delivery of the Multicast Address Procedure of Multicast Address Allocation

26. B C D A E A B C D E 1 1 1 1 1 2 3 4 6 5 7 Service of Multicast Application: Allocation of a unique Multicast Address for a new Session

27. Multicast DNS

28. Introduction • Name Service in MANET • MANET has dynamic network topology • Current DNS can not be adopted in MANET! • Because it needs a fixed and well-known name server • Idea of Name Service in MANET • All the mobile nodes take part in name service • Every mobile node administers its own name information • It responds to the other node’s DNS query related to its domain name and IP address

29. LLMNR Sender LLMNR Responder LLMNR query message (What is IPv6 address of “host.private.local”?) - It is sent in link-local multicast LLMNR response message (IPv6 address of “host.private.local”) - It is sent in link-local unicast Verification of LLMNR response- Does the value of the response conform to the addressing requirements? - Is hop-limit of IPv6 header 1? If the result is valid, then the Sender caches and passes the response to the application that initiated DNS query. else the Sender ignores the response and continues to wait for other responses. Related Work: Link-Local Multicast Name Resolution (LLMNR) • DNS service based on IP multicast in link-local scoped network • Each node performs the role of DNS name server for its own domain name.

30. Ad Hoc Name Service Systemfor IPv6 MANET (ANS) • ANS provides Name Service in MANET • Architecture of ANS System • ANS Responder • It performs the role of DNS Name Server • ANS Resolver • It performs the role of DNS Resolver

31. ANS System (1/2)

32. Application ANS Resolver ANS Responder Main-Thread ANS Cache Main-Thread ANSZone DB Resolv-Thread Timer-Thread DUR-Thread Process Thread Memeory Read / Write Process Memeory Read / Write Cache Internal Connection Thread Internal Connection Database ANS System (2/2) UNIX Datagram Socket

33. Name Service in ANS • Name Generation • generates a unique domain name based on the network device identifier • Zone File Generation • generates ANS zone file with the unique domain name and corresponding IPv6 address • Name Resolution • performs the name-to-address translation

34. Conclusion for Multicast DNS • ANS is a new name service scheme in MANET. • Name service of ANS • Automatic name generation • Automatic zone file generation • Name-to-address translation • Future work • ANS will be enhanced to provide secure name service. • Authentication of DNS response message through Pre-shared group key and IPsec ESP’s null-transform

35. Service Discovery

36. Service Discovery • Definition • Discovery of the location (IP address, Transport-layer protocol, Port number) of server that provides some service. • Methods • Multicast DNS based Service Discovery • Service discovery through Multicast DNS and DNS SRV resource record, which indicates the location of server or the multicast address of the service • SLP based Service Discovery • Service discovery through IETF Service Location Protocol (SLP) • RFC 2165, RFC 2608, RFC 3111

37. Considerations for Service Discovery • Limitations of Existing Schemes • Most of current schemes are concerned with service location for the Internet. • Such protocols have not taken into account the mobility, packet loss issues and latency. • Considerations • Some devices are small and have limited computation, memory, and storage capability. • They can only act as clients, not servers. • Power constraints • Service discovery should not incur excessive messaging over wireless interface.

38. $TTL 20 $ORIGIN ADHOC. PAUL-1 IN AAAA FEC0:0:0:FFFF:3656:78FF:FE9A:BCDE ;; DNS SRV Resource Records; Unicast Service : SERVICE-1 _SERVICE-1._TCP IN SRV 0 1 3000 PAUL-1.ADHOC. _SERVICE-1._UDP IN SRV 0 1 3000 PAUL-1.ADHOC.; Multicast Service : SERVICE-2 _SERVICE-2._UDP IN SRV 0 1 4000 @.1.5. DNS SRV Resource Record for Multicast Service Multicast Service Name 8 4 4 112 Parsing Function MD5 Hash Function FF Group ID Flags label & Scope label 128-bit Digest FlagsP=0, T=1 Scope5 16-bit IPv6 Site-localMulticast Address Prefix + Group ID=Low-order 112 bits of Digest IPv6 Site-local Multicast Address Service Discovery based on Multicast DNS ANS Responder’s Zone File IPv6 Multicast Address corresponding to Service Name Generation of IPv6 Multicast Address

39. Scenario of Service Discovery MN-A MN-C MN-B Request ofServer Information DNS Query Messagefor Service Information DNS Query Messageis sent in Multicast Receipt of DNS Query Message DNS Query Messagefor Service Information Receipt and Processof DNS Query Messagerelated toDNS SRV resource record DNS Response Messagewith Service Information Gain ofService Information MN-C tries to connect to the server on MN-AorMN-C joins the multicast group related to MN-A The server on MN-A accepts the request of the connection from MN-CorThe multicast group comprises MN-A and MN-C

40. Protocol Stack supporting MANET Autoconfiguration

41. Conclusion • MANET Autoconfiguration • Unicast Address Autoconfiguration • Multicast Address Allocation • Multicast DNS • Service Discovery • Autoconfiguration Technologies in MANET • They can provide Ad Hoc users with auto-networking. • They should be default functions for the deployment of MANET. • Also, security in MANET is important issue and is considered together in auto-networking in MANET.

42. References [1] Jaehoon Jeong, Hyunwook Cha, Jungsoo Park and Hyoungjun Kim, “Ad Hoc IP Address Autoconfiguration”, draft-jeong-adhoc-ip-addr-autoconf-00.txt, May 2003. [2] Nitin H. Vaidya, “Weak Duplicate Address Detection in Mobile Ad Hoc Networks”, MobiHoc2002, June 2002. [3] Charles E. Perkins et al., “IP Address Autoconfiguration for Ad Hoc Networks”, draft-ietf-manet-autoconf-01.txt, November 2001. [4] Jaehoon Jeong and Jungsoo Park, “Autoconfiguration Technologies for IPv6 Multicast Service in Mobile Ad-hoc Networks”, 10th IEEE International Conference on Networks, August 2002. [5] Jung-Soo Park and Myung-Ki Shin, “Link Scoped IPv6 Multicast Addresses”, draft-ietf-ipv6-link-scoped-mcast-02.txt, July 2002. [6] Jaehoon Jeong, Jungsoo Park, Hyoungjun Kim and Kishik Park, “Name Service in IPv6 Mobile Ad-hoc Network”, ICOIN2003, February 2003. [7] Gulbrandsen, P. Vixie and L. Esibov, “A DNS RR for specifying the location of services (DNS SRV)”, RFC2782, February 2000. [8] Jaehoon Jeong, Jungsoo Park, and Hyoungjun Kim, “Service Discovery based on Multicast DNS in IPv6 Mobile Ad-hoc Networks”, VTC2003 Spring, April 2003.