1. IPv6 over 802.16’s IPv6 Convergence Sublayer draft-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 ’s IPv6 CS – Solution
Scope of the draft
Way Forward

3. WiMAX Network Architecture
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
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
MS 1
ASN GW
MS 2
BS 1
MS 3
MS 4
BS 2
ASN R1 R6 R3

4. Proposed Solution IP Link Access Router Prefix Assignment
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
MS 1
ASN GW
MS 2
BS 1
MS 3
MS 4
BS 2
ASN R1 R6 R3
Link

5. Neighbor Discovery … Router Discovery Periodic RAs Prefix Assignment
Send an unsolicited RA as soon as the initial 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 NUD Redirect Hop Count
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 Loss of DAD Probe
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?