© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IPv6 Transition Mechanisms Implementing Dual Stack

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Both IPv4 and IPv6 stacks are enabled. Applications can talk to both. Choice of the IP version is based on name lookup and application preference. Dual Stack UDPTCP IPv4IPv6 "Old" Application Data Link (Ethernet) 0x08000x86dd Frame Protocol ID UDPTCP IPv4IPv6 "New" Application Data Link (Ethernet) 0x08000x86dd

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Dual-Stack Operation An application that is not aware of IPv6 or is forcing the use of IPv4: –Asks the DNS for IPv4 address –Connects to the IPv4 address What is the IPv4 A record for DNS Server IPv4IPv6

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Dual-Stack Operation: IPv6-Only An application that is only IPv6-enabled, or has to use IPv6 because it is the only stack, or is forcing the use of IPv6: –Asks the DNS for IPv6 address –Connects to the IPv6 address What is the IPv6 AAAA record for :db8::1 DNS Server IPv4IPv6 2001:db8::1

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Dual-Stack Operation: Dual-Stack In a dual-stack case, An IPv4-enabled and IPv6-enabled application asks the DNS for all types of addresses: –Chooses one address –Connects…for example, to the IPv6 address 2001:db8:: = * ? DNS Server IPv4IPv6 2001:db8::1

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Dual-Stack Address Host Selection Process Dual Stack Stage 1: DNS request sent Stage 2: DNS server sends answer Stage 3: Application selects correct address Stage 4: Application connects to destination host

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Cisco IOS Dual Stack Cisco IOS software is IPv6-ready: If IPv4 and IPv6 addresses are configured on an interface, the interface is dual stacked. Router1(config)# ipv6 unicast-routing interface Ethernet0 ip address ipv6 address 2001:db8:c18:1::3/64 IPv4: IPv6: 2001:db8:800:1::3 Dual Stack Router1 IPv4/IPv6 Network

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Steps to Implement Dual Stack in an IP Network There are basic steps required to implement a dual stack approach. Step 1 -Review the network, application, and security aspects of your environment Step 2 - Upgrade both hosts, routers, and infrastructure services to support IPv6 Step 3 - Enable IPv6 support Step 4 - Upgrade all services where possible to provide IPv6 functionality Step 5 - Ensure that dual-stack operation is functioning correctly

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Using the Dual Stack Approach Advantages of using dual stacking as the primary approach to IPv6 integration: Relatively simple approach Can be less costly in the short-term Continue to leverage existing v4 infrastructure Allows indefinite coexistence between IPv4 and IPv6 Issues of using dual stacking as the primary approach to IPv6 integration: Can be more costly over the long term Increased network complexity

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Summary Dual stack networks allow applications to choose to run over IPv4 or IPv6 transport, because the nodes are configured to do either. Dual stack is a relatively easy method to integrate IPv6 into an existing IPv4 environment because there is wide support for IPv6 in most modern operating systems, but may create a more complex network environment.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v