Changes in protocol support in Microsoft’s instant messaging (IM) products mean that organizations will have to update new Windows XP desktops to work with Exchange 2000 IM systems.

Why the Update Is Required

The update is necessary because of rapidly changing protocols in the IM space. Exchange 2000 used the Rendezvous Protocol (RVP), which was similar to Internet Messaging and Presence Protocol (IMPP), a protocol endorsed by the Internet Engineering Task Force (IETF). RVP is supported in the MSN Messenger client software, which until the release of Windows XP was the standard Windows messaging client. This meant that users could employ the MSN Messenger client in Exchange-based IM systems. (See "Exchange 2000 Includes Instant Messaging Capability " on page 9 of the Nov. 2000 Update.)

However, the IETF and the rest of the industry have moved away from IMPP and toward a new, more flexible standard, Session Initiation Protocol (SIP), which supports many real-time media formats, including video, audio, and data. (For background, see "Session Initiation Protocol" on page 10 of the Aug. 2001 Update.)

Windows Messenger, the IM client that ships with Windows XP, supports SIP so that it can offer new features, such as one-to-one videoconferencing and application sharing. (See "Windows Messenger Moves IM, Conferencing in New Direction" on page 8 of the Aug. 2001 Update.) However, it does not support RVP.

Where to Get It

The update adds RVP support to Windows Messenger, and will be available for download at windowsupdate.microsoft.com and www.microsoft.com/exchange/downloads/2000/ on Oct. 25, the same day that Windows XP itself is launched. The update also lets Windows Messenger users place PC-to-voice calls; see "Messenger Update Adds PC-to-Phone Ability" for more information.

Desktop PCs that already have the older MSN Messenger client and that are upgraded to Windows XP will not require the update. In these cases, the new Windows Messenger client will automatically incorporate the RVP support from the old MSN Messenger client during the upgrade.