Changes to Protocols

   

There are numerous protocol changes in Windows Server 2003, and the following sections describe them:

  • TCP/IP Changes and Enhancements

  • IPv6 Protocol Stack

  • Kernel-Mode Processing of Web Traffic

  • Quality of Service Enhancements

TCP/IP Changes and Enhancements

The following changes and enhancements have been made to the TCP/IP protocol for the Windows Server 2003 family:

  • TCP/IP Protocol cannot be removed.

    The TCP/IP protocol ”called Internet Protocol (TCP/IP) in the properties of a connection in the Network Connections folder ”is installed by default and cannot be removed. One step in troubleshooting a possible TCP/IP configuration problem has been to remove the TCP/IP protocol and reinstall it. This is no longer possible in the Windows Server 2003 family. Instead, you can use a new Netsh command to reset the TCP/IP configuration to installation defaults. For more information, see the upcoming item "Netsh command to reset TCP/IP defaults."

  • Automatic alternate configuration for multiple networks connectivity.

    Alternate configuration allows you to manually configure static TCP/IP settings that are configured when the computer is a Dynamic Host Configuration Protocol (DHCP) client and no DHCP server is found when the computer starts. For computers running Windows 2000, Windows 98, and Windows Me, if the computer configured as a DHCP client does not find a DHCP server, Automatic Private IP Addressing (APIPA) assigns a unique address from the 169.254.0.0.16 address space. Although APIPA allows TCP/IP to start, it does not assign a default gateway address, a Domain Name System (DNS) server IP address, or other settings essential for communication on an intranet or the Internet. Alternate configuration is useful in situations in which the computer is used on more than one network, one of those networks does not have a DHCP server, and an APIPA addressing configuration is not desired.

    For example, a user has a laptop computer that is used at the office and at home. While at the office, the computer uses a DHCP-allocated TCP/IP configuration. While at home, where no DHCP server is present, the laptop computer automatically uses the alternate configuration, which provides easy access to home network computers and the Internet. With alternate configuration, you do not have to manually reconfigure TCP/IP settings when the laptop computer is connected to either the office or the home network.

    You can configure the TCP/IP alternate configuration on the Alternate Configuration tab from the properties of the Internet Protocol (TCP/IP) protocol in the properties of a LAN connection in the Network Connections folder.

  • Netsh command to reset TCP/IP defaults.

    A new Netsh command has been added to the Windows Server 2003 family to allow you to reset your TCP/IP configuration to its default values. The new Netsh command is netsh interface ip reset and is issued at the command prompt.

    In earlier versions of Windows, you could remove the Internet Protocol (TCP/IP) protocol and reinstall it with the same effect. With the Windows Server 2003 family, TCP/IP is installed by default and cannot be removed. This feature can be useful for IT administrators who find that the computer user has changed the TCP/IP configuration for a computer to unsupported values.

  • New Netstat option to display TCP port ownership.

    A new option is added to the Netstat tool that allows you to display active TCP connections and that includes the Process Identifier (PID) for each connection. You can find the application based on the PID on the Processes tab in Windows Task Manager. By default, the PID is not displayed in the Windows Task Manager. To configure the Windows Task Manager to display the PID, click View, click Select Columns, click PID (Process Identifier) in the list of columns to display, and then click OK.

  • IGMP version 3.

    IGMPv3 provides source-based multicast group membership reporting. Hosts can request to receive multicast traffic from specified sources or from all but a specific set of sources. Source-specific reporting prevents multicast-enabled routers from delivering multicast traffic to a subnet where there are no listening hosts for the source of the multicast traffic. IGMPv3 support is enabled by default and requires no configuration.

  • Autodetermination of routing metrics based on interface speed.

    This feature allows the TCP/IP protocol to automatically determine the routing metric for routes derived from the TCP/IP configuration based on the speed of its associated interface. For example, routes derived from the TCP/IP configuration of 10-Mbps Ethernet network adapters have a routing metric of 30, and routes derived from the TCP/IP configuration of 100-Mbps Ethernet network adapters have a routing metric of 20.

    This feature is useful if you have multiple interfaces of different speeds that are configured to use the same default gateway; the fastest interface has the lowest routing metric for its default route and is used to forward traffic to its default gateway. If there are multiple interfaces of the fastest speed, the interface that is listed first in the binding order is used to forward traffic to its default gateway. Automatic determination of the interface metric is enabled by default through the Automatic metric check box on the IP Settings tab and when you manually configure default gateways in Advanced TCP/IP Settings from the properties of the Internet Protocol (TCP/IP) protocol from a connection in the Network Connections folder.

  • TCP receive window size determined by the local network adapter.

    The window size determines the maximum number of bytes that can be sent without requiring an acknowledgment. On a slower-speed dial-up network connection, the window size is almost equal to the size of the queue on the remote access server. When the queue is filled with TCP segments from one TCP connection, a new TCP connection cannot be established until all these packets are sent. Additionally, the TCP slow-start algorithm on the new connection makes the situation worse . With this feature, the Quality of Service (QoS) Packet Scheduler on a computer with ICS will adjust the advertised window size to match the dial-up network connection speed. This will reduce the queue depth at the remote access server and enable new connections to work better.

    In a home network, all the home computers are typically on a high-speed LAN and access the Internet through an ICS computer. The ICS computer is connected to the Internet using a dial-up modem. When one home computer is doing a large file transfer, other home computers might get slow performance when accessing the Internet (for example, when using a Web browser). With this feature, new Internet TCP connections from the other home computers are much more responsive . This feature is enabled by default only when ICS is used and requires no configuration.

IPv6 Protocol Stack

The Windows Server 2003 family includes an IPv6 protocol stack that is designed for production use. The IPv6 protocol for the Windows Server 2003 family includes the following features:

  • Windows Sockets support.

    The Windows Server 2003 family includes support for the new Windows Sockets functions getaddrinfo and getnameinfo to perform name-to-address and address-to-name resolution for Windows Sockets applications, as described in RFC 2553. Using these functions, rather than getaddrbyname and gethostbyname , you can make your Windows Sockets applications independent of the version of IP (IPv4 or IPv6) that is running on the computer.

  • 6to4 tunneling.

    6to4 tunneling is a tunneling technique that's described in RFC 3056. A component of the IPv6 protocol for the Windows Server 2003 family, 6to4 allows automatic tunneling and IPv6 connectivity between IPv6/IPv4 hosts across the IPv4 intranet. 6to4 hosts use IPv6 addresses derived from IPv4 public addresses. With 6to4, IPv6 sites and hosts can use 6to4-based addresses and the IPv4 Internet to communicate without having to obtain an IPv6 global address prefix from an ISP and connecting to the IPv6 Internet.

  • Intrasite Automatic Tunnel Addressing Protocol.

    Intrasite Automatic Tunnel Addressing Protocol (ISATAP) is an address assignment and automatic tunneling mechanism that allows IPv6/IPv4 nodes within an IPv4 infrastructure of a site to use IPv6 to communicate with one another and with nodes on an IPv6-enabled network, either within the site or on the IPv6 Internet.

  • PortProxy.

    The PortProxy component facilitates the communication among nodes or applications that cannot connect using a common Internet layer protocol (IPv4 or IPv6). PortProxy allows the proxying of TCP traffic for the following: IPv4 to IPv4, IPv4 to IPv6, Server 2003IPv6 to IPv6, and IPv6 to IPv4. For IPv6/IPv4 coexistence and migration, PortProxy enables the following scenarios:

    • An IPv4-only node can access an IPv6-only node.

    • An IPv6-only node can access an IPv4-only node.

    • An IPv6 node can access an IPv4-only service running on an IPv6/IPv4 node.

    This last scenario allows computers running the IPv6 protocol for the Windows Server 2003 family to use IPv6 to access Web pages on a computer running a member of the Windows 2000 Server family and Internet Information Services (IIS). Windows 2000 IIS does not support IPv6. Therefore, the only way to access it is by using IPv4. When PortProxy is configured on a computer running a member of the Windows Server 2003 family, incoming IPv6-based Web requests are proxied to the Windows 2000 IIS server, allowing the IIS server to communicate indirectly with IPv6-enabled Web browsers.

    To configure the PortProxy service, use the netsh interface portproxy addsetdelete v4tov4v4tov6v6tov4v6tov6 commands.

  • Site Prefixes in Router Advertisements.

    Published on-link prefixes can be configured with a site prefix length. You can use the netsh interface ipv6 addset route commands to include a site prefix length with the address prefix.

    When a prefix information option that specifies a site prefix is received, an entry is created in the site prefix table. You can view this table by using the netsh interface ipv6 siteprefixes command. The site prefix table is used to remove inappropriate site-local addresses from those that are returned by the getaddrinfo Windows Sockets function.

  • DNS support.

    Processing for Domain Name System (DNS) IPv6 host records (known as AAAA, or quad-A, resource records), as defined in RFC 1886, "DNS Extensions to support IP version 6," and for dynamic registration of AAAA records is supported by the DNS resolver (client) in the Windows Server 2003 family and the DNS Server service in Windows Server 2003 family and Windows 2000. DNS traffic is supported over both IPv6 and IPv4.

  • IPSec support.

    Processing for the Authentication Header (AH) using the Message Digest 5 (MD5) hash and for the Encapsulating Security Payload (ESP) using the NULL ESP header and the MD5 hash is supported. There is no support for ESP data encryption or the IKE protocol. IPSec security policies, security associations, and encryption keys must be manually configured using the Ipsec6.exe tool.

  • Operating system component and application support.

    System components and applications provided with the Windows Server 2003 family that support the use of IPv6 include Internet Explorer, the Telnet client (Telnet.exe), the FTP client (Ftp.exe), IIS 6.0, file and print sharing (the Server and Workstation services), Windows Media Services, and Network Monitor.

  • RPC support.

    RPC functions are used to forward application function calls to a remote system across the network. The RPC components in the Windows Server 2003 family are IPv6-enabled. The RPC components have been modified to use the updated Windows Sockets, which allows RPC to work over both IPv4 and IPv6.

  • IP Helper API support.

    Internet Protocol Helper (IP Helper) is an API that assists in the administration of the network configuration of the local computer. You can use IP Helper to programmatically retrieve information about the network configuration of the local computer and to modify that configuration. IP Helper also provides notification mechanisms to ensure that an application is notified when certain aspects of the network configuration change on the local computer. IP Helper in the Windows Server 2003 family has been extended to allow the retrieval of information for IPv6 and its components.

  • Static router support.

    A computer running the Windows Server 2003 family can act as a static IPv6 router that forwards IPv6 packets between interfaces based on the contents of the IPv6 routing table. You can configure static routes with the netsh interface ipv6 add route command. No IPv6 routing protocols are provided for the Routing and Remote Access service.

    A computer running the Windows Server 2003 family can send router advertisements. The contents of router advertisements are automatically derived from the published routes in the routing table. Nonpublished routes are used for routing but are not sent in router advertisements. Router advertisements always contain a source link-layer address option and a Maximum Transmission Unit (MTU) option. The value for the MTU option is taken from the sending interface's current link MTU. You can change this value with the netsh interface ipv6 set interface command. A computer running a member of the Windows Server 2003 family will advertise itself as a default router (by using a router advertisement with a router lifetime other than 0) only if a default route is configured to be published.

Kernel-Mode Processing of Web Traffic

HTTP.sys is a kernel-mode implementation of both the client and server sides of the Hypertext Transfer Protocol (HTTP). It aims to provide a scalable, efficient implementation of HTTP that allows the use of true Win32 asynchronous I/O, including the ability to bind request and response completion to completion ports. The user-mode API for the client side will be exposed via existing APIs such as WinHTTP and the .NET Framework Classes. The server side of HTTP.sys is provided in the Windows Server 2003 family and is used by IIS 6.0. The complete version of HTTP.sys that includes both client and server will be provided in a future version of Windows.

Quality of Service Enhancements

When a home network is connected to a corporate or other network through a slow link, such as a dial-up line, a situation can exist that will increase the delay of traffic traversing the slow link.

If the receiving client is running on a relatively fast network (100-Mbps Ethernet, for example) behind an ICS box and the server with which this receiver is communicating behind the remote access box is using a fast network, a mismatch exists. In this scenario, the receiver's receive window is set to a large value based on the speed of the connection. The sender begins sending at a slow rate, but because packets aren't lost, the sender eventually increases to sending nearly a full window size of packets.

This can affect the performance of other TCP connections that traverse the same network, making their packets wait in this potentially large queue. If packet loss occurs, a full window size has to be retransmitted, further congesting the link. The solution to this is to have the ICS computer on the edge of the network set the receive window to a smaller size appropriate to the slow link, overriding the receiver's specification. This setting will not adversely affect traffic as the window size is being set as it would if the receiver were connected directly to the slow link. The QoS packet scheduler component running on the ICS computer makes this window adjustment.

Additional information about QoS can be found on the Windows 2000 Networking and Communications Services Web site at: http://www.microsoft.com/windows2000/technologies/communications/.


   
Top


Introducing Microsoft Windows Server 2003
Introducing Microsoft Windows Server(TM) 2003
ISBN: 0735615705
EAN: 2147483647
Year: 2005
Pages: 153

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net