G. Chelius, E. Fleury

1

IPv6 router auto-configuration using
OSPFv3 ltdraft-chelius-router-autoconf-00.txtgt

• G. Chelius, E. Fleury
• gchelius_at_telecom.insa-lyon.fr, Eric.Fleury_at_inria.f
  r
• L. Toutain
• Laurent.Toutain_at_enst-bretagne.fr

2
Objectives

• Home networking
• Multi-technology (Ethernet, 802.11, Bluetooth,
  IEEE1394, power lines)
• Complex topology
• Possible loops, possible multi-homing
• No IPv6 network administration skill
• gt Difficult to manually assign subnet numbers
• Use of OSPFv3 to automatically assign subnet
  numbers
• Use of the OSPF database synchronization
• Definition of 3 new LSA types

3
Announcement of prefix numbers (TLA)

• TLA-Site LSA
• Originated by edge routers
• Flooding scope site
• Announce an available prefix throughout the
  network
• Multi-homing
• Several prefix database entries
• Different prefix originators
• Upon reception, routers update global prefixes
• If no global prefix entry, use the site local
  prefix

4
How to get a subnet value consensus on a link

• SLA-Link LSA
• Originated by the links Designated Router (DR)
• Flooding scope link
• Create a consensus on the link (subnet number,
  length, Link ID)
• Mapping between Link ID and subnet number
• Link IDs are large numbers to avoid collisions
• At link creation
• DR imposes its Link ID subnet number

5
Link merging or partitioning

• Election of a new designated router
• If old DR is dead (may be link partitioning)
• New Link ID new subnet number
• If old DR still present on the link
• Same Link ID same subnet number
• Link merging
• One of the two Link ID subnet number disappears

6
Announcement of allocated subnet numbers (SLA)

• SLA-Area LSA
• Originated by the links designated router
• Flooding scope area
• Announce allocated TLASLA and Link IDs
  throughout the area
• Avoid collision when a new subnet number is
  chosen
• Knowledge of attributed subnet numbers using
  SLA-Area entries
• Collision detection when another Link ID use the
  same TLASLA
• Smallest Link ID renumbers its subnet number

7
Issues

• Auto-configuration of OSPFv3 router IDs
• 32 bits
• Manually configured
• What do we want to be unique ?
• SLA value (only one SLA per link) or
• TLASLA value (decreases collision risk,
  increases complexity)
• Implementation status
• Implemented in Zebra ospf6d
• See http//citi.insa-lyon.fr/gchelius/dslac/