including router priority, route summarization, and so on.
Web Links Configuring OSPFv3
http://cisco.com/en/US/products/sw/iosswrel/
ps5187/products_configuration_guide_chapter
09186a00801d660d.html#wp1137651

Content 8.5 Implementing and Verifying OSPFv3 8.5.2 Enabling OSPFv3 on an Interface Most of the OSPFv3 configuration is done on the interface. Figure displays a sample configuration enabling an IPv6 IP address, area, router priority, and path cost. Figure provides descriptions of the required interface commands and optional commands including router priority, and OSPFv3 path cost.

Content 8.5 Implementing and Verifying OSPFv3 8.5.3 Configuring OSPFv3 Routing Specifics OSPFv3 routing specifics are configured from router configuration mode. To enter router configuration mode, use the ipv6 router ospf process-id command. This command enables an OSPF process on the router. The process ID parameter identifies a unique OSPFv3 process. For an IPv6-only router, a router ID parameter must be defined in the OSPFv3 configuration as an IPv4 address using the router-id router-id router configuration command. OSPFv3 uses a 32-bit number for a router ID. The OSPFv3 router ID can be expressed in dotted decimal, allowing easy overlay of an OSPFv3 network on an existing OSPFv2 network. Figure displays a sample configuration. If IPv4 is configured on the router, by default, the router ID is chosen in the same way as it is with OSPFv2. The highest IPv4 address configured on a loopback interface becomes the router ID. If no loopback interfaces are configured, the highest address on any other interface becomes the router ID.

Content 8.5 Implementing and Verifying OSPFv3 8.5.4 OSPFv3 Route Summarization Figure displays sample OSPFv3 routes before summarization. To consolidate and summarize routes at an area boundary, use the area area-id range ipv6-prefix/prefix-length [advertise | not-advertise] [cost cost] IPv6 OSPF router command. Figure provides a sample configuration. The cost of the summarized routes is the highest cost of the routes being summarized. For example, the routes displayed in Figure become one summarized route as displayed in Figure .

Content 8.5 Implementing and Verifying OSPFv3 8.5.5 OSPFv3 Configuration Example The example in Figure shows an OSPF network of two routers, with an area 0 and area 1. The interface-specific command ipv6 ospf 100 area 0 creates the “ipv6 router ospf 100” process dynamically, as does the ipv6 ospf 100 area 1 command.

Content 8.5 Implementing and Verifying OSPFv3 8.5.6 Verifying OSPFv3 There are several commonly used OSPFv3 show commands, including the show ipv6 ospf [process-id] [area-id] interface [interface] command. This command generates OSPF-related interface information, as displayed in Figure . The clear ipv6 ospf [process-id] {process | force-spf | redistribution | counters [neighbor [neighbor-interface | neighbor-id]]} command triggers SPF recalculation and repopulation of the Routing Information Base (RIB). The show ipv6 ospf [process-id] [area-id] command displays general information about OSPF processes, as shown in Figures and . Figure lists some of the show ipv6 ospf command output fields and descriptions.

Content 8.5 Implementing and Verifying OSPFv3 8.5.7 Verifying OSPFv3 Neighbors To display OSPF neighbor information on a per-interface basis, use the show ipv6 ospf neighbor command in user EXEC or privileged EXEC mode. The show ipv6 ospf neighbor detail command provides detailed information about IPv6 OSPF neighbors, as illustrated in Figure . Figure displays the show ipv6 ospf neighbor command output fields and descriptions.

Content 8.5 Implementing and Verifying OSPFv3 8.5.8 Verifying OSPFv3 Database To display lists of information related to the OSPF database for a specific router, use the show ipv6 ospf database command in user EXEC or privileged EXEC mode. The various forms of this command deliver information about different OSPF link-state advertisements (LSAs). Figures and illustrate sample partial output from the show ipv6 ospf database command. Figure provides show ipv6 ospf database command output field descriptions. Figure illustrates sample output from the show ipv6 ospf database database-summary command.

Content 8.6 Using IPv6 and IPv4 8.6.1 IPv6 to IPv4 Transition Mechanism The transition from IPv4 to IPv6 does not require an upgrade on all nodes at the same time. Many transition mechanisms enable smooth integration of IPv4 to IPv6. There are mechanisms available that allow IPv4 nodes to communicate with IPv6 nodes. All of these mechanisms can be applied to different situations. The two most common techniques to transition from IPv4 to IPv6 are as follows:

Dual stack
IPv6-over-IPv4 (6to4) tunnels

For communication between IPv4 and IPv6 networks, IPv4 addresses can be encapsulated in IPv6 addresses. Figure displays an example of a transition and integration mechanism. The 6to4 routers automatically encapsulate the IPv6 traffic inside IPv4 packets. Web Links IPv6 Deployment Strategies
http://cisco.com/en/US/tech/tk872/technologies
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Content 8.6 Using IPv6 and IPv4 8.6.2 Cisco IOS Dual Stack Most newer versions of Cisco IOS software are IPv6-ready. As soon as IPv4 and IPv6 basic configurations are complete on the interface, the interface is dual-stacked, and it forwards IPv4 and IPv6 traffic. Using IPv6 on a Cisco IOS router requires that you use the global configuration command ipv6 unicast-routing. This command enables the forwarding of IPv6 datagrams. All interfaces that forward IPv6 traffic must have an IPv6 address. The ipv6 address [IPv6-address] [/prefix length] command specifies an IPv6 network assigned to the interface and enables IPv6 processing on the interface. Dual stack is an integration method where a node has implementation and connectivity to both an IPv4 and IPv6 network, and thus the node has two stacks. This configuration can be accomplished on the same interface or on multiple interfaces. Considerations for dual-stack include the following:

A dual-stack node chooses which stack to use based on the destination address. A dual-stack node prefers IPv6 when available. The dual-stack approach to IPv6 integration in which nodes have both IPv4 and IPv6 stacks will be one of the most commonly used integration methods. Old IPv4-only applications continue to work as before. New and modified applications take advantage of both IP layers.
A new application programming interface (API) is defined to support both IPv4 and IPv6 addresses and Domain Name System (DNS) requests. This API replaces the gethostbyname and gethostbyaddr calls. A converted application can make use of both IPv4 and IPv6. An application can be converted to the new API while still using only IPv4.
Past experience in porting IPv4 applications to IPv6 suggests that for most applications it is a minimal change in some localized places inside the source code. This technique is well known and has been applied in the past for other protocol transitions. It enables gradual application upgrades, one by one, to IPv6.

Content 8.6 Using IPv6 and IPv4 8.6.3 Overlay Tunnels Networking often uses tunnels to overlay an incompatible functionality on an existing network. Tunneling IPv6 traffic over an IPv4 network requires one edge router to encapsulate the IPv6 packet inside an IPv4 packet and another router to decapsulate it. This