IPv6%20over%20802.16

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IPv6 over 802.16s IPv6 Convergence
Sublayerdraft-madanapalli-ipv6-over-802.16-ipv6cs
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• Syam Madanapalli
• Basavaraj Patil
• Erik Nordmark
• JinHyeock Choi
• Soohong D. Park

IETF 66 Montreal 9-14 July 2006
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Agenda

• Introduction to WiMAX Network Architecture
• IPv6 over 802.16s IPv6 CS Solution
• Scope of the draft
• Way Forward

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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
• 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

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Proposed Solution

• 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

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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 gt 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

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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

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Address Autoconfiguration

• Interface Identifier generation
• Generate the IID from MSs 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

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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

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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

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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?

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Way Forward

• Include other deployment scenarios?
• Accept as WG document?

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