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Transition and Tunnels

Transition and Tunnels. Dale Finkelson. Transition. There are really two types of cases that need to be addressed. Network layer How can we get v6/v4 packets across v4/v6 networks? Host layer How can a v6/v4 host access content on a v4/v6 host?. Network layer transition. Tunnels

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Transition and Tunnels

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  1. Transition and Tunnels Dale Finkelson

  2. Transition • There are really two types of cases that need to be addressed. • Network layer • How can we get v6/v4 packets across v4/v6 networks? • Host layer • How can a v6/v4 host access content on a v4/v6 host?

  3. Network layer transition • Tunnels • Dual Stack

  4. Tunnels • Information from one protocol is encapsulated inside the frame of another protocol. • This enables the original data to be carried over a second non-native architecture. • 3 steps in creating a tunnel • Encapsulation • Decapsulation • management

  5. Tunnels • There are at least 4 tunnel configurations: • Router to router • Host to router • Host to host • Router to host • Required information: • V4 address of the tunnel endpoints. • Note that private addresses will not work here.

  6. Tunnels • How the addresses are known determines the type of tunnel. • Configured tunnel • Automatic tunnel • Multicast tunnel

  7. Configured tunnel • These can be unidirectional or bidirectional. • Bidirectional looks like a point-to-point link • The administrator configures the tunnel. • Examples of this would be the pre-native Abilene backbone and some types of tunnel brokers.

  8. Automatic Tunnel • A tunnel is created without the intervention of a network administrator. • Typically this involves the v4 address of the endpoint being contained within the v6 address. • Isatap and 6to4 are examples • 6to4 uses 2002::/16 plus the 32 bit v4 address to form a /48. • Isatap treats the v4 network as layer 2 transport. • V4 address is in the interface identifier

  9. Tunnel Broker • Ultimate automagic version is http://www.freenet6.net/ • Handles changing IPv4 address on your host (DHCP’d, etc) • Slightly manual version is http://carmen.ipv6.tilab.com/ipv6/tools/ipv6tb/index.html • CERNET has open source tunnel broker

  10. Automatic Tunnel (6to4) • Uses an IPv4 compatible address • Assumes dual stack on your host • Requires an IPv4 “relay” host (for full connectivity) • Converts a.b.c.d IPv4 into 2002:AB:CD::/48 (convert a into hex) • http://www.kfu.com/~nsayer/6to4/

  11. Dual Stack • Obvious. • This is likely to be the predominate network layer transition tool. • When all the tools using tunnel mechanisms were developed I do not believe anyone thought viable dual stack routers would show up as quickly as they in fact have. • Most backbones will be (or could be) dual stack very easily and will be when there is a demand.

  12. Transition • Tunnels will remain useful as a tool for connecting isolated hosts in home networks to v6 nets.

  13. Host level transition • This is where transition could bog down. • How do you make web and other servers transparently accessable to either v6 or v4 hosts. • There are several approaches. • Dual stack • Bump-in-the-stack • Nat like devices • translators

  14. Translators • Within Linux variants there is a tool called Faithd. • This is a transport layer translator. • There are also header translators out there: • SIIT • Nat-PT • Socks • Various application specific translators.

  15. Summary • This is neither as hard as it was once thought nor as easy as we might like to make it. • Dual Stack will be viable much sooner then was thought. • It is merely an act of faith and will to convert existing servers to v6 capable versions.

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