IPv6 Transition Mechanisms

Transcription

1 Transition Mechanisms A set of protocol mechanisms implemented in hosts and routers. To allow and IPv4 hosts to interoperate. Because it is impossible to have a flag day for all hosts to upgrade from IPv4 to. To allow hosts and routers to be deployed in the Internet in a highly diffuse and incremental fashion, with few interdependencies The transition should be as transparent to general users as possible 1

2 簡介

3 NGtrans 規劃之轉換機制

4 IPv4 to Transition Strategy (RFC 2893) Dual Stack Reduce the cost invested in transition by running both IPv4/ protocols on the same machine. Tunneling Reduce the cost in wiring by re-using current IPv4 routing infrastructures as a virtual link. Translation (RFC 2766 NAT-PT) Allow realm to access the rich contents already developed on IPv4 applications From 16-bit DOS to 32-bit Windows From 4-byte IPv4 to 16-byte 4

5 APPLICATION Dual-Stack Approach TCP/UDP IPv4 DRIVER When adding to a system, do not delete IPv4 This multi-protocol approach is familiar and well-understood (e.g., for AppleTalk, IPX, etc.) Note: in most cases, will be bundled with new OS releases, not an extra-cost add-on (e.g., Windows Vista/7, CentOS 5, FreeBSD 8) Applications (or libraries) choose IP version to use when initiating, based on DNS response: if (dest has AAAA or A6 record) use, else use IPv4 when responding, based on version of initiating packet This allows indefinite co-existence of IPv4 and, and gradual, app-by-app upgrades to usage 5

6 簡易雙重架構機制 IPv4 Stack 功能啟動, 而 功能關閉 ( 即 IPv4-only node) Stack 功能啟動, 而 IPv4 功能關閉 ( 即 -only node) IPv4 Stack 及 Stack 功能皆啟動 (node 具組態切換功能 )

7 IPv4/ 雙重架構機制

8 Dual Stack Approach & DNS = *? IPv4 DNS Server 2001:DB8:: In a dual stack case, an application that: Is IPv4 and -enabled Asks the DNS for all types of addresses 2001:DB8::1 Chooses one address and, for example, connects to the address 8

9 Dual Stack Approach Application -enable Application Preferred method on Application s servers TCP UDP TCP UDP IPv4 0x0800 0x86dd Data Link (Ethernet) IPv4 0x0800 0x86dd Data Link (Ethernet) Frame Protocol ID Dual stack node means: Both IPv4 and stacks enabled Applications can talk to both Choice of the IP version is based on name lookup and application preference 9

10 Cisco IOS Dual Stack Configuration and IPv4 Network Dual-Stack Router IPv4: router# interface Ethernet0 ip address ipv6 address 2001:C58:213:1::/64 eui-64 : 2001:C58:213:1::/64 eui-64 Cisco IOS is -enable: If IPv4 and are configured on one interface, the router is dual-stacked Telnet, Ping, Traceroute, SSH, DNS client, TFTP, 10

11 ping 11

12 DNS Queries of A and AAAA Records 12

13 Exercise Try to turn off on your PC, and repeat the above test. What are the differences? 13

14 IPv4 to Transition Strategy (RFC 2893) Dual Stack Reduce the cost invested in transition by running both IPv4/ protocols on the same machine. Tunneling Reduce the cost in wiring by re-using current IPv4 routing infrastructures as a virtual link. Translation (RFC 2766 NAT-PT) Allow realm to access the rich contents already developed on IPv4 applications From 16-bit DOS to 32-bit Windows From 4-byte IPv4 to 16-byte 14

15 Tunnels of over IPv4 Header Transport Header Data Host Network Dual-Stack Router IPv4 Dual-Stack Router Network Host IPv4 Header Tunnel: in IPv4 packet Header Transport Header Data Encapsulating the packet in an IPv4 packet Tunneling can be used by routers and hosts 15

16 Tunneling Network Tunnel Service Provider IPv4 Backbone Tunnel IPv4 Header Header Header Transport Layer Header Transport Layer Header Data Data Network Tunnel 16

17 Manually Configured Tunnel Network Dual-Stack Router1 IPv4 Dual-Stack Router2 Network router1# IPv4: : 2001:DB8:c18:1::3 IPv4: : 2001:DB8:c18:1::2 router2# interface Tunnel0 ipv6 address 2001:DB8:c18:1::3/64 tunnel source tunnel destination tunnel mode ipv6ip interface Tunnel0 ipv6 address 2001:DB8:c18:1::2/64 tunnel source tunnel destination tunnel mode ipv6ip Manually Configured tunnels require: Dual stack end points Both IPv4 and addresses configured at each end 17