IPv6 over 802.16’s IPv6 Convergence Sublayer draft-madanapalli-ipv6-over-802.16-ipv6cs-00

1. IPv6 over 802.16’s IPv6 Convergence Sublayerdraft-madanapalli-ipv6-over-802.16-ipv6cs-00 Syam Madanapalli Basavaraj Patil Erik Nordmark JinHyeock Choi Soohong D. Park IETF 66 – Montreal 9-14 July 2006

2. Agenda • Introduction to WiMAX Network Architecture • IPv6 over 802.16’s IPv6 CS – Solution • Scope of the draft • Way Forward

3. WiMAX Network Architecture R1 MS 1 ASN R6 BS 1 MS 2 R3 ASNGW MS 3 BS 2 MS 4 • ASN GW - Omniscient AR • Knows about all nodes attached to itself • Only one AR at any given time • MAC Transport Connection • Always exists between MS and ASN GW • 802.16 MAC connection between MS and BS • R6 GRE tunnel between BS and ASN GW • Initial Service Flow • Created as soon as completion of Network Entry • Can be used for autoconfiguration

4. Proposed Solution Link R1 MS 1 ASN R6 BS 1 MS 2 R3 ASNGW MS 3 BS 2 MS 4 • IP Link • The ASN GW, Multiple BSs attached to the ASN GW and all MS attached to these BSs are all on same IP Link • Access Router • ASN GW is the first-hop AR • Prefix Assignment • One or more prefixes are shared among the MSs

5. Neighbor Discovery … • Router Discovery • Send an unsolicited RA as soon as the initial 802.16 transport connection has been established • Or just do RS/RA • Periodic RAs • Send them in unicast manner • MaxRtrAdvInterval > 1800 sec. • Prefix Assignment • One or more prefixes are shared among the nodes on the link • Prefixes are advertised with on-link flag (L-bit) reset and autonomous address-configuration flag (A-bit) set • Next-Hop • Always the ASN GW for an MS • An intelligent implementations need not perform this • No direct communication is allowed between two MSs

6. Neighbor Discovery • Address Resolution • Not required • But the existing implementations may attempt address resolution • AR just ignores the NS • After no response, MS sends the packet to the AR, the default router • NUD • Required because an MS may have more than one IPv6 address • Can be performed as specified in 2461bis • Redirect • ASN GW should not redirect for the packets destined to the same IP Link • Hop Count • Should not be decremented for the on-link communication

7. Address Autoconfiguration • Interface Identifier generation • Generate the IID from MS’s 48-bit MAC address as per RFC2464 • Optionally, it is allowed to use Privacy Extensions as specified in RFC 3041 • Duplicate Address Detection • MS behavior is as specified in 2462bis • DAD is performed using Relay DAD

8. Relay DAD • ASN GW Maintains Address Cache • List of IPv6 addresses that are currently in use including solicited-node multicast addresses. • Learns the addresses from DAD NS, if the address is not duplicate • Learns the Solicited-Node Multicast Addresses from MLD Join • Relays the DAD Probe if there is a match in the address cache for the destination solicited node multicast address • MS responds to the DAD Probe if the address is duplicate • Address Cache entries expire when • Prefix life time expires • MS or another entity deregisters explicitly • R6 GRE tunnel for the MS is deleted • NS/NA exchange with longer intervals

9. Issues • Address Cache overflow • AR should limit the no. of addresses an MS can have at any given time • Loss of DAD Probe • Do we need to dealt with it? • Tunnel between BS and AR • Should be per MS for IP CS

10. Scope of the document • Current scope covers only WiMAX Network Architecture • Should 16ng consider other deployment scenarios? • Should this document cover the other scenarios? Or WG allows writing another draft?

11. Way Forward • Include other deployment scenarios? • Accept as WG document?