OSPF IPv6 Extensions 



V6 Area Option 

   o  Supports both IPv4 and IPv6 addresses 
   o  May maintain two routing tables or single IPv6 routing table 
      -  If single routing table must translate IPv4 addresses to 
         IPv6 address 
   o  V6 area may be stub area, transit area (including backbone), 
      NSSA area 
   o  Runs on top of IPv6 
   o  All routers in v6 area must agree on IPv4 support or routing 
      may break 
      -  All or none 



Topology 

   o  IPv6 in area 1.1.1.1 only 
   o  Area 1.1.1.1 networks only reachable to rest of AS if networks 
      are translated or have both v4 and v6 addresses 

             _______________________________
            /                               \
           /                                 \
           |        Area 0.0.0.0 (BB)        | 
           \                                 /
            \_______________________________/
             __|__                     __|__
            |     |                   |     |
            |_____|                   |_____|
       ________|_______            ______|_________ 
      /                \          /                \
      |  Area 1.1.1.1  |          |  Area 2.2.2.2  |
      |      IPv6      |          |                |
      \________________/          \________________/



Topology 

   o  IPv4 networks (from area 2.2.2.2) sent through AS 
   o  IPv6 networks only reachable to area 2.2.2.2 if other areas 
      also have IPv4 networks (or are translated) 

             _______________________________
            /                               \
           /        Area 0.0.0.0 (BB)        \
           |              IPv6               | 
           \                                 /
            \_______________________________/
             __|__                     __|__
            |     |                   |     |
            |_____|                   |_____|
       ________|_______            ______|_________ 
      /                \          /                \
      |  Area 1.1.1.1  |          |  Area 2.2.2.2  |
      |      IPv6      |          |                |
      \________________/          \________________/



Packet Formats 

   o  Identical to IPv4 formats (Hellos, DD, LsReq) but have bigger 
      addresses 
      -  Link-state ID field is 128 bits 
      -  Advertising router field is 128 bits 
      -  Area ID field is 128 bits 
   o  Net mask field is 32 bits 
      -  Identifies number of bits of a contiguous network mask 



Link-State Advertisements 

   o  Correspond to current OSPF LSA types 
      -  Type 17 = Type 1 (router links) 
      -  Type 18 = Type 2 (network links), etc. 
   o  128-bit LS ID, 128-bit router ID, 32-bit mask length field 
   o  IPv4 LSAs (summaries, externals) may be flooded into v6 areas 
      but v6 LSAs are never flooded into IPv4 areas 



V6 Router Links Advertisements 

   o  Includes both IPv4 and IPv6 links 
      -  Equivalent link types but with big fields 
      -  E.g., Type 17 = Type 1: point-to-point connection 
   o  New router link type (21) for IPv4 router ID 
      -  SPF calculations 
      -  Needed for AS boundary summary LSAs 



Router Link Fragmentation 

   o  Needed for bigger addresses 
      -  Avoid IP fragmentation 
   o  Advertising router identifies router 
   o  Link-state ID identifies fragment 



Opaque LSA 

   o  Method to distribute information using OSPF database 
      distribution mechanism 
   o  Uses the `P' (propagate) bit as defined in NSSA option 
      -  Added by originator of LSA 
   o  Flag border routers to redistribute LSA to other v6 areas 



Opaque LSA Usage 

   o  Flood AS path information (BGP/IDRP) 
   o  Flood public key information 
   o  If IPX addresses embedded into IPv6 can use opaque to flood 
      SAP information 
   o  QoS information/attributes 
   o  LS ID 
      -  First 32 bits type 
      -  Next 96 bits are defined by type 



Migration 

   o  Run v6 as backbone 
   o  Run v6 as stub areas 
   o  Single or v4 and v6 routing tables 
   o  Can run existing IPv4 protocols (RIP, BGP) as well as IPv6