1IETF-59 MANET WG Ad Hoc IP Address Autoconfiguration Jaehoon Jeong ETRI 3 rd February 2004 draft-jeong-adhoc-ip-addr-autoconf-01.txt

2IETF-59 MANET WG Contents Motivation of the Draft Framework of the Draft Address Autoconfiguration Message Format IP Address Generation Duplicate Address Detection Maintenance of Upper-layer Sessions Future Work

3IETF-59 MANET WG Motivation of the Draft Four basic MANET unicast routing protocols will have been published as experimental RFC soon. –AODV, DSR, OLSR and TBRPF AODV and OLSR have already been published as RFC. Next step? –Addressing is as essential as Routing Automatic IP address configuration is necessary in MANET, which has dynamic topology. –Various approaches have been suggested in research domain Stateless vs. Stateful approaches Strong DAD vs. Weak DAD Active DAD vs. Passive DAD Therefore, it is time to develop MANET IP Address Autoconfiguration in engineering mode.

4IETF-59 MANET WG Framework of the Draft 1.IP Address Generation 2.Duplicate Address Detection -Hybid scheme considering MANET partition Strong DAD Weak DAD 3. Maintenance of Upper-layer Sessions

5IETF-59 MANET WG Address Autoconfiguration Message Format | Type | Code | Checksum | | Identification | | Originator IP Address | | Requested or Duplicate IP Address | Type: - AREQ: Address Request - AREP: Address Reply - AERR: Address Error Code: - 0: default - 1: indication of address change in type AERR

6IETF-59 MANET WG IP Address Generation Selection of Random IP Address –IPv4 IPV4_MANET_PREFIX + 16-bit Random Number – /16 is used as IPV4_MANET_PREFIX. –There is a great possibility of address conflicts by Birthday Paradox. »Nodes of two to the power eight (= 256) will generate at least one address collision with a probability of 50%. –IPv6 IPV6_MANET_PREFIX + 64-bit Random Number –fec0:0:0:ffff::/64 is used as IPV6_MANET_PREFIX. »Because of the deprecation of IPv6 site-local address, a new local prefix for local networks separated from the Internet is necessary.

7IETF-59 MANET WG Duplicate Address Detection Phase 1 : Strong DAD –Time-based DAD For detecting IP address duplication in a connected MANET partition within a finite bounded time interval –Strong DAD is performed during the initiation of node’s network interface. Phase 2 : Weak DAD –Routing-based DAD For detecting IP address duplication during ad hoc routing It can handle the address duplication by MANET partition and mergence. Key is used for the purpose of detecting duplicate IP addresses. –Virtual IP Address = IP Address + Key

8IETF-59 MANET WG Process of Duplicate Address during Weak DAD Each node investigates the virtual IP address contained in ad hoc routing control packet –to see if there is the same address with different key in routing table or cache. If there is the duplicate IP address, –The node sends an AERR (Address Error) message to another node using duplicate address that is associated with a different key. The node, receiving the AERR message, auto- configures a new IP address –through Strong DAD

9IETF-59 MANET WG Maintenance of Upper-layer Sessions Consequence of Address Replacement –When address duplication happens and the duplicate address is replaced with another, the sessions above network layer can be broken. There should be a mechanism to guarantee the survivability of upper-layer sessions –Announcement of address change to peer-nodes is needed. It is performed through AERR message. –Victim Node Selection Node performing route discovery will be victim node that regenerates its address and informs its peers of the address change.

10IETF-59 MANET WG Data Delivery after resolving Address Duplication Data Delivery through IP Tunneling –After the delivery of AERR message, the peer node and announced node exchange data packets through IP tunneling. –Address Mapping Cache is needed like a binding cache of MIP. Peer Node Address : IP pn Announced Node New Address : IP new Old Address : IP old Data Packet SRC Addr : IP pn DEST Addr : IP new SRC Addr : IP pn DEST Addr : IP old Payload Outer IP Header Inner IP Header

11IETF-59 MANET WG Future Work Maintenance of Upper-layer Sessions –Victim Node Selection Consideration of the number of on-going sessions Consideration of fairness Address Mapping Cache –Data structure of the cache and how to maintain it Applicability into each MANET routing protocol. –A new draft, “Ad Hoc IP Address Autoconfiguration for AODV”, will be submitted to this 59th meeting.