In computing, Microsoft's Windows Vista and Windows Server 2008 introduced in 2007/2008 a new networking stack named Next Generation TCP/IP stack, to improve on the previous stack in several ways. The stack includes native implementation of IPv6, as well as a complete overhaul of IPv4. The new TCP/IP stack uses a new method to store configuration settings that enables more dynamic control and does not require a computer restart after a change in settings. The new stack, implemented as a dual-stack model, depends on a strong host-model and features an infrastructure to enable more modular components that one can dynamically insert and remove.

Architecture

The Next Generation TCP/IP stack connects to NICs via a Network Driver Interface Specification (NDIS) driver. The network stack, implemented in tcpip.sys implements the Transport, Network and Data link layers of the TCP/IP model. The Transport layer includes implementations for TCP, UDP and unformatted RAW protocols. At the Network layer, IPv4 and IPv6 protocols are implemented in a dual-stack architecture. And the Data link layer (also called Framing layer) implements 802.3, 802.1, PPP, Loopback and tunnelling protocols. Each layer can accommodate Windows Filtering Platform (WFP) shims, which allows packets at that layer to be introspected and also host the WFP Callout API. The networking API is exposed via three components: Winsock A user mode API for abstracting network communication using sockets and ports. Datagram sockets are used for UDP, whereas Stream sockets are for TCP. While Winsock is a user mode library, it uses a kernel mode driver, called Ancillary Function Driver (AFD) to implement certain functionality. Winsock Kernel (WSK) A kernel-mode API providing the same socket-and-port abstraction as Winsock, while exposing other features such as Asynchronous I/O using I/O request packets. Transport Driver Interface (TDI) A kernel-mode API which can be used for legacy protocols like NetBIOS. It includes a component, known as TDX to map the TDI functionality to the network stack.

User interface

The user interface for configuring, troubleshooting and working with network connections has changed significantly from prior versions of Windows as well. Users can make use of the new "Network and Sharing Center" to see the status of their network connections, and to access every aspect of configuration. A single icon in the notification area (system tray) represents connectivity through all network adapters, whether wired or wireless. The network can be browsed using Network Explorer, which replaces Windows XP's "My Network Places". Network Explorer items can be a shared device such as a scanner, or a file share. The Network Location Awareness (NLA) service uniquely identifies each network and exposes the network's attributes and connectivity type so that applications can determine the optimal network configuration. However, applications have to use the NLA APIs explicitly to be aware of the network connectivity changes, and adapt accordingly. Windows Vista uses the Link Layer Topology Discovery (LLTD) protocol to graphically present how different devices are connected over a network, as a Network Map. In addition, the Network Map uses LLTD to determine connectivity information and media type (wired or wireless), so that the map is topologically accurate. The ability to know network topology is important for diagnosing and solving networking problems, and for streaming content over a network connection. Any device can implement LLTD to appear on the Network Map with an icon representing the device, allowing users one-click access to the device's user interface. When LLTD is invoked, it provides metadata about the device that contains static or state information, such as the MAC address, IPv4/IPv6 address, signal strength etc.

Network classification by location Windows Vista classifies the networks it connects to as either Public, Private or Domain and uses Network Location Awareness to switch between network types. Different network types have different firewall policies. An open network such as a public wireless network is classified as Public and is the most restrictive of all network settings. In this mode other computers on the network are not trusted and external access to the computer, including sharing of files and printers, is disabled. A home network is classified as Private, and it enables file sharing between computers. If the computer is joined to a domain, the network is classified as a Domain network; in such a network the policies are set by the domain controller. When a network is first connected to, Windows Vista prompts to choose the correct network type. On subsequent connections to the network, the service is used to gain information on which network is connected to and automatically switch to the network configuration for the connected network. Windows Vista introduces a concept of network profiles. For each network, the system stores the IP address, DNS server, Proxy server and other network features specific to the network in that network's profile. So when that network is subsequently connected to, the settings need not be reconfigured, the ones saved in its profile are used. In the case of mobile machines, the network profiles are chosen automatically based on what networks are available. Each profile is part of either a Public, Private or Domain network.

Internet Protocol v6 The Windows Vista networking stack supports the dual Internet Protocol (IP) layer architecture in which the IPv4 and IPv6 implementations share common Transport and Framing layers. Windows Vista provides a GUI for configuration of both IPv4 and IPv6 properties. IPv6 is now supported by all networking components and services. The Windows Vista DNS client can use IPv6 transport. Internet Explorer in Windows Vista and other applications that use WinINet (Windows Mail, file sharing) support literal IPv6 addresses (). Windows Firewall and the IPsec Policies snap-in support IPv6 addresses as permissible character strings. In IPv6 mode, Windows Vista can use the Link Local Multicast Name Resolution (LLMNR) protocol, as described in , to resolve names of local hosts on a network which does not have a DNS server running. This service is useful for networks without a central managing server, and for ad hoc wireless networks. IPv6 can also be used over PPP-based dial-up and PPPoE connections. Windows Vista can also act as a client/server for file sharing or DCOM over IPv6. Support for DHCPv6, which can be used with IPv6, is also included. IPv6 can even be used when full native IPv6 connectivity is not available, using Teredo tunneling; this can even traverse most IPv4 symmetric Network Address Translations (NATs) as well. Full support for multicast is also included, via the MLDv2 and SSM protocols. The IPv6 interface ID is randomly generated for permanent autoconfigured IPv6 addresses to prevent determining the MAC address based on known company IDs of NIC manufacturers.

Wireless networks Support for wireless networks is built into the network stack itself as a new set of APIs called Native Wifi, and does not emulate wired connections, as was the case with previous versions of Windows. This allows implementation of wireless-specific features such as larger frame sizes and optimized error recovery procedures. Native Wifi is exposed by Auto Configuration Module (ACM) which replaces Windows XP's Wireless Zero Configuration. The ACM is extensible, so developers can incorporate additional wireless functionality (such as automatic wireless roaming) and override the automatic configuration and connection logic without affecting the built-in framework. It is easier to find wireless networks in range and tell which networks are open and which are closed. Hidden wireless networks, which do not advertise their name (SSID) are better supported. Security for wireless networks is improved with improved support for newer wireless standards like 802.11i. EAP-TLS is the default authentication mode. Connections are made at the most secure connection level supported by the wireless access point. WPA2 can be used even in ad-hoc mode. Windows Vista also provides a Fast Roaming service that will allow users to move from one access point to another without loss of connectivity. Preauthentication with the new wireless access point can be used to retain the connectivity. Wireless networks are managed from either the Connect to a network dialog box within the GUI or the netsh wlan command from the shell. Settings for wireless networks can also be configured using Group policy.

Windows Vista enhances security when joining a domain over a wireless network. It can use Single Sign On to use the same credentials to join a wireless network as well as the domain housed within the network. In this case, the same RADIUS server is used for both PEAP authentication for joining the network and MS-CHAP v2 authentication to log into the domain. A bootstrap wireless profile can also be created on the wireless client, which first authenticates the computer to the wireless network and joins the network. At this stage, the machine still does not have any access to the domain resources. The machine will run a script, stored either on the system or on USB thumb drive, which authenticates it to the domain. Authentication can be done either by using username and password combination or security certificates from a Public key infrastructure (PKI) vendor such as VeriSign.

Wireless setup and configuration

Windows Vista features Windows Connect Now which supports setting up a wireless network using several methods supported in the Wi-Fi Protected Setup standard. It implements a native code API, Web Services for Devices (WSDAPI) to support Devices Profile for Web Services (DPWS) and also a managed code implementation in WCF. DPWS enables simpler device discoverability like UPnP and describes available services to those clients. Function Discovery is a new technology that serves as an abstraction layer between applications and devices, allowing applications to discover devices by referencing the device's function, rather than by its bus type or the nature of its connection. Plug and Play Extensions (PnP-X) allow network-connected devices to appear as local devices inside Windows connected physically. UPnP support has also been enhanced to include integration with PnP-X and Function Discovery.

Network performance