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

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

3. 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. 4 MANET Auto-configuration Unicast Address Autoconfiguration Multicast Address Allocation Multicast DNS Service Discovery MANET Autoconfiguration Multicast DNS Service Discovery Multicast Address Allocation Unicast Address Autoconfiguration

5. 5

6. 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. 7 Strong DAD Definition A i (t) : Address assigned to node i at time t. For each address a != undefined, S a (t) = {j | A j (t) = a}. Condition of Strong DAD Within a finite bounded time interval after t, at least one node in S a (t) will detect that |S a (t)| > 1.

8. 8 Host A Router Host B Wireless Link NS message NA message Host C Where NS : Neighbor Solicitation, NA : Neighbor Advertisement MAC & IPv6 Address of Host C   MAC Address – a9:bb:cc:dd:ee:ff   IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff 1 st Try of Host A   MAC Address - a9:bb:cc:dd:ee:ff   IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff MANET PrefixEUI-64 2 nd 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

9. 9 Generation of Tentative address with MANET_PREFIX and 64-bit Number Generation of 64-bit Random Number Was any extended NA message received from any other node? YESNO Reconfiguration of Unicast address in NIC Transmission of Extended NS message   MANET_INIT_PREFIX   fec0:0:0:ffff::/96   MANET_PREFIX   fec0:0:0:ffff::/64 Generation of 32-bit Random Number and 64-bit Random Number Generation of Temporary address with MANET_INIT_PREFIX and 32-bit Number Procedure of Strong DAD This iteration is performed by predefined retry-number.

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

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

12. 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. 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. 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. 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. 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. 17 Link State Routing with Strong DAD A C E D B DestNext Hop IP_B IP_CIP_E IP_AIP_B IP_E Routing table at node D FromToCost IP_DIP_E2 IP_DIP_B10 Link state packet transmitted by D

18. 18 Link State Routing with Weak DAD DestDest Key Next Hop IP_BK_BIP_B IP_CK_CIP_E IP_AK_AIP_B IP_EK_EIP_E Routing table at node D FromFrom Key ToTo Key Cost IP_DK_DIP_EK_E2 IP_DK_DIP_BK_B10 Link state packet transmitted by D A C E D B

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

20. 20 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. 21 Phases of Hybid DAD 1 st Phase By Strong DAD Time-based DAD It is performed in the stage for IPv6 address to be configured in network interface. 2 nd 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. 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. 23 Multicast Address Allocation

24. 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 ID of IPv6 unicast address (b).

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

26. 26 Service of Multicast Application : Allocation of a unique Multicast Address for a new Session BCD EA ABCDE 1 2 3 4 5 6 7 1111 StepAction 1Unicast Address Autoconfiguration 2Run of Video-conferencing Tool (e.g., SDR) and Creation of a new Session -> Multicast Address Allocation 3Advertisement of Session Information 4MN A’s join to the new Session 5MN E’s join to the new Session 6Transmission of Video/Audio Data by MN A 7Transmission of Video/Audio Data by MN E

27. 27 Multicast DNS

28. 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. 29 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. LLMNR SenderLLMNR 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.

30. 30 Ad Hoc Name Service System for 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. 31 ANS System (1/2)

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

33. 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. 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. 35 Service Discovery

36. 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. 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. 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. Service Discovery based on Multicast DNS Group IDFF Flags P=0, T=1 Scope 5 841124 Multicast Service Name + 128-bit Digest MD5 Hash Function Group ID=Low-order 112 bits of Digest DNS SRV Resource Record for Multicast Service Flags label & Scope label Parsing Function 16-bit IPv6 Site-local Multicast Address Prefix IPv6 Site-local Multicast Address ANS Responder’s Zone File IPv6 Multicast Address corresponding to Service Name Generation of IPv6 Multicast Address

39. 39 Scenario of Service Discovery MN-C MN-B MN-A DNS Query Message for Service Information DNS Query Message is sent in Multicast Receipt of DNS Query Message Request of Server Information Receipt and Process of DNS Query Message related to DNS SRV resource record DNS Response Message with Service Information Gain of Service Information MN-C tries to connect to the server on MN-A or MN-C joins the multicast group related to MN-A The server on MN-A accepts the request of the connection from MN-C or The multicast group comprises MN-A and MN-C DNS Query Message for Service Information

40. 40 Protocol Stack supporting MANET Autoconfiguration

41. 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. 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.