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Windows XP and Broadband Internet Connections

Published: November 01, 2001
By Joseph Davies

Abstract

Windows XP has built-in support for the Point-to-Point Protocol over Ethernet (PPPoE). This allows a computer running Windows XP to connect to any Internet service provider whose access equipment supports PPPoE for broadband Internet connections, which includes both cable modem and Digital Subscriber Line (DSL) technologies. Configuring Windows XP for a PPPoE connection is as simple as creating a new connection using the New Connection Wizard. Internet service providers that support industry-standard PPPoE server functionality will work with the PPPoE client supplied in Windows XP.

Acknowledgements

Rob Trace, Program Manager

David Eitelbach, Program Manager

On This Page

Introduction
PPPoE Support in Windows XP
How to Configure Windows XP for PPPoE
Does my ISP Support Windows XP?
Issues with Windows XP PPPoE support
Summary
Related Links

Introduction

Internet service providers (ISPs) that use broadband Internet access technologies deployed in a bridged Ethernet topology, such as cable modem or Digital Subscriber Line (DSL), need a way to distinguish individual users so that Internet usage can be accounted for, and, if appropriate, billed to individual users. Because Ethernet is inherently a shared access technology, it provides no such facilities. By combining the Point-to-Point Protocol (PPP) with Ethernet, an ISP can use Ethernet topologies and still maintain the individuality of user access as if they were using a dial-up modem. The type of access and choice of service are managed on a per-user basis, rather than a per-site or per-access device basis. The combination of PPP and Ethernet is known as Point-to-Point Protocol over Ethernet (PPPoE) and is defined in the Internet Engineering Task Force RFC 2516.

PPPoE works in the following way:

  • A PPPoE frame is an Ethernet frame that contains as its payload a PPP frame encapsulated with a PPPoE header.

  • When a connection to the Internet is attempted, the PPPoE Discovery phase negotiates the use of a PPPoE session. After the PPPoE session is established, PPP negotiation begins and a PPP connection is established in the same way as if the user were dialing the ISP with a dial-up modem.

  • When the PPP session negotiation is complete, PPP frames encapsulated with a PPPoE header are sent as Ethernet frames.

PPPoE requires the following:

  • The ISP must have access equipment that operates as a PPPoE server. This support includes the ability to send and receive Ethernet frames, receive and negotiate PPPoE sessions, and receive and negotiate PPP connections.

  • The Internet user must have a computer that operates as a PPPoE client on their Internet connection. This support includes the ability to send and receive Ethernet frames, initiate and negotiate PPPoE sessions, and initiate and negotiate PPP connections.

PPPoE Support in Windows XP

Windows XP includes built-in client support for PPPoE connections. You create a PPPoE connection using the Create a new connection network task or using the New Connection Wizard in the Network Connections folder. After you create a PPPoE connection, it appears in the Network Connections folder as a Broadband connection. With a PPPoE connection, you can:

  • Enable Internet Connection Sharing to share the PPPoE connection with other computers on your home network.

  • Enable Internet Connection Firewall to protect the computer with the PPPoE connection from Internet attacks.

  • Use the PPPoE connection as part of a double-dial virtual private network (VPN) connection. In a double-dial VPN connection, one connection is used to connect to the Internet and another connection is used to create a VPN connection to an organization intranet (such as your employer's network).

  • Configure the PPPoE connection for Internet use within Internet Explorer and other Windows applications.

How to Configure Windows XP for PPPoE

To create a broadband connection using PPPoE, use the following procedure:

  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.

  2. Under Network Tasks, click Create a new connection, and then click Next.

  3. Click Connect to the Internet, and then click Next.

  4. Click Setup my connection manually, and then click Next.

  5. Click Connect using a broadband connection that requires a user name and password.

  6. In the Connection Name dialog box, type the name of the ISP. This becomes the name of the connection. Click Next.

  7. In the Internet Account Information dialog box, type the user name and password. Additional checkboxes allow you to specify whether this connection and its user name and password is available to all users (selected by default), whether this connection is your default Internet connection (selected by default), and whether to enable the Internet Connection Firewall on the connection (enabled by default). Make the appropriate selections, and then click Next.

  8. In the Completing the Connection Wizard dialog box, review the settings. If you need to modify any of them, click Back as many times as necessary. If all the settings are correct, click Finish.

  9. In the Connect dialog box, click Connect to attempt the connection.

Does my ISP Support Windows XP?

A common question is whether your ISP supports Windows XP for broadband Internet connections based on PPPoE. The simple answer is this:

If your ISP supports RFC 2516-complaint PPPoE, then it supports PPPoE in Windows XP.

The PPPoE client in Windows XP is based on the industry standard described in IETF RFC 2516 and should work with any ISP access hardware operating as a PPPoE server that is based on the industry standard described in IETF RFC 2516.

Issues with Windows XP PPPoE support

The following are issues with Windows XP PPPoE support.

PPPoE Service Names

PPPoE support in Windows XP is designed so that the user does not need to configure a PPPoE service name. A PPPoE service name is either an ISP name or a class of service that is configured on the PPPoE server. There is no facility in the properties of the PPPoE connection that allows you to discover the service name.

By default, a Windows XP PPPoE connection has a blank service name. When you click Connect to create a PPPoE connection, Windows XP attempts to connect using the blank service name. If there are no access devices using a blank service name, then Windows XP will try the connection again using the first service name from the first access device that responded to the first connection attempt. Thus, Windows XP discovers the service name during the connection attempt. This provides the simplest configuration and works for most users. If a specific service name is required, a service name can be configured on the General tab from the properties of the PPPoE connection.

Maximum Transmission Unit

There is no ability to configure the maximum transmission unit (MTU) of the PPPoE connection from the properties of the connection. By default, a Windows XP PPPoE connection supports an IP MTU of 1480 bytes. The 20 bytes of overhead consist of the PPPoE header (6 bytes), the largest possible outer PPP header (4 bytes), the largest possible Multilink PPP header (4 bytes), the largest possible PPP header for compression and encryption (4 bytes), and the PPP header that identifies the actual packet being sent (2 bytes).

Don't Use Password Authentication Protocol for PPP Authentication

It is highly recommended that the ISP not use Password Authentication Protocol (PAP) for PPP authentication. When PAP is used as the PPP authentication protocol, the Internet user's name and password are sent on the network in a clear text form. Computers connected to the network segment of the access device could capture these packets and easily determine the user names and passwords of connecting users.

Windows XP PPPoE connections support PAP authentication and, by default, the PPPoE connection allows the use of unsecured passwords. Windows XP PPPoE connection will attempt to use secured password authentication protocols such as Microsoft Challenge Handshake Authentication Protocol version 2 (MS-CHAP v2), Microsoft Challenge Handshake Authentication Protocol (MS-CHAP), Challenge Handshake Authentication Protocol (CHAP), and Shiva Password Authentication Protocol (SPAP), before offering to use PAP.

Microsoft recommends that you use MS-CHAP v2, MS-CHAP, or CHAP for your authentication protocol. If your ISP supports one of these secured password authentication protocols and you want to ensure that PAP and SPAP are never used, select Require secured password under Validate my identity as follows using typical security settings on the Security tab from the properties of the PPPoE connection

Problems with Third Party PPPoE Products

PPPoE support in Microsoft Windows operating systems such as Windows 95, Windows 98, and Windows Millennium Edition is provided by third-party vendors. You are not required to use the PPPoE support provided with Windows XP. However, if you want to use a third-party PPPoE component with Windows XP, please consult the PPPoE vendor to ensure that the version of the product you are installing has been updated to support Windows XP. There are known compatibility issues with WinPoET version 2.1a or earlier, Enternet 300 version 1.34 or earlier, and RASPPPoE. If updated third-party components are not yet available, you can use the PPPoE client included with Windows XP as an interim solution to obtain Internet connectivity.

Summary

PPPoE support is now provided with Windows XP and very easy to configure. If your ISP supports RFC 2516-compliant PPPoE-based broadband connections, then your ISP supports Windows XP.

Related Links

See the following resources for further information:

For the latest information about Windows XP, see the Windows XP Web site at http://www.microsoft.com/windowsxp/default.asp.

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