IPv6 Transitioning

Summary of Transition high level methods (notes for my reference).

The problem is that IPv6 isn’t compatible with IPv4 so we need to have a method to either…

  • Dual Stack. Simply run both IPv4 and IPv6 together. Separate Routing Tables!
  • Translate. Convert IPv6 to IPv4 somewhere using NAT-PT (RFC4966.  converting IPv6 ⇔ IPv4 on a boundary device) or NAT64 (RFC6144. Allows communication to IPv6 Server.  Need NAT64 Prefix, NAT64 router and DNS64 server)  See ipspace post and Simon Perreaults Post. (NAT ALG working at application layer
  • Tunnel.  
    • All the below are variations of GRE tunnels (except manual)…
      • Create the tunnel interface
      • Define the source and destination
      • Configure IPv6 prefix if req, and tunnel mode…
    • Manual Carry IPv6 over IPv4 networks
      • (tunnel mode: ipv6ip)
      • (P2P)
      • (Req DualStack)
    • *Automatic 6to4* Joining IPv6 Islands together.
      • (tunnel mode: ipv6ip 6to4)
      • (P2M (like a NBMA cloud))
      • (2002::/16 Range) specifically 2002:border-router-ipv4-address::/48
      • Per Packet
      • Tunnel destination not needed (In the IPv6 tunnel address)
      • 1 Auto6to4 tunnel per router
    • *ISATAP* Connect IPv6 hosts within a site
      • (No Multicast ∴  No ND ∴ No Routing Protocols!!!)
      • (tunnel mode: ipv6ip isatap)
      • (P2M)
      • <GUA/LLA-prefix>:000:5EFE:<IPv4-of-ISATAP-Link>
      • Must use EUI-64 method
      • Tunnels normally disable NS RA’s!!!  Must reenable…”no ipv6 nd suppress-ra
    • Automatic IPv4 Compatible  Depreciated.  Use ISATAP! 
      • (tunnel mode: ipv6ip auto-tunnel)
      • (P2M)
      • (Req DualStack)
      • (::/96 Range) Low order /32 from the IPv4 address.
    • IPv6 over IPv4 GRE Joining IPv6 islands again on Edge Routers.  .  
      • (tunnel mode: gre ip)
      • (P2P)
      • (Req DualStack)
      • Supports other protocols and IPSec

Other Notes:

  • 6RD (Rapid Deployment) (ISPs)
    • (tunnel mode: ipv6ip 6rd)
    • Similar to 6to4, but since not using 2002::/16 6rd is less prone to internet routing issues.
    • Uses CE router (aka RD or residential gateway) to tunnel traffic through an IPv4 network to another CE or border router(or BR’s using anycast).
    • Stateless.
  • IPv6 over MPLS
    • Uses MP-BGP and IPv4 addresses embedded as the next hop
    • 6PE uses the global IPv6 routing table
    • 6VPE uses VRF Tables on PE Router


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