IPv6 Stack

Basic IPv6 Stack Support
The IPv6 protocol for Windows Server 2008 and Windows Vista supports Internet Engineering Task Force (IETF) standards for IPv6 protocol stack functionality, including the following:

• The IPv6 header (RFC 2460)

• Unicast, multicast, and anycast addressing (RFC 4291)

• The Internet Control Message Protocol for IPv6 (ICMPv6) (RFC 4443)

• Neighbor Discovery (ND) (RFC 4861)

• Multicast Listener Discovery (MLD) (RFC 2710) and MLD version 2 (MLD v2)
(RFC 3810)

• Stateless address autoconfiguration (RFC 4862)


IPv6 Stack Enhancements
The IPv6 protocol for Windows Server 2008 and Windows Vista also supports the following enhancements:

• Dead gateway detection through neighbor unreachability detection Dead gateway detection automatically switches the currently used default router to the next one in a configured list when the current default router becomes unavailable, as detected through neighbor unreachability detection.

• Explicit Congestion Notification support (RFC 3168) When a TCP segment is lost, TCP assumes that the segment was lost due to congestion at a router and performs congestion control, which dramatically lowers the TCP sender’s transmission rate. With Explicit Congestion Notification (ECN) support on both TCP peers and in the routing infrastructure, routers experiencing congestion mark the packets as they forward them. TCP peers receiving marked packets lower their transmission rate to ease congestion and prevent segment losses. Detecting congestion before packet losses are incurred increases the overall throughput between TCP peers. Windows Server 2008 and Windows Vista support ECN, but it is disabled by default. You can enable ECN support with the netsh interface tcp set global ecncapability=enabled command.

• Default route preferences and Route Information options in router advertisements (RFC 4191) With default router preferences, you can configure the advertising routers on a subnet to indicate a preference level so that hosts use the most preferred router as their default router. With Route Information options in router advertisements, routers that do not advertise themselves as default routers can advertise directly attached routes to hosts.

• Strong host model for both sending and receiving The strong host model requires that unicast traffic sent or received must be associated with the network interface on which the traffic is sent or received. For sent traffic, IPv6 can send packets on an interface only if the interface is assigned the source IPv6 address of the packet being sent. For received traffic, IPv6 can receive packets on an interface only if the interface is assigned the destination IPv6 address of the packet being received.

Source of Information : Microsoft Press Understanding IPv6 2nd Edition