Fundamental design problems with Microsoft's Active Directory (AD) that will affect early adopters of Windows 2000 (W2K), will not be fixed until next year, a senior analyst has warned.

Ed Thompson, an analyst at Gartner, said the design problems, which involve network performance and the stability of directory services when deployed to over 300 sites, are not fixed by the recent release of Service Pack 1 for W2K.

Likewise, W2K Datacenter Server, released last Friday, does not address problems which include the stability of AD.

Other areas of concern include the broadcast of global catalogue replication, which means that replicating Exchange 2000 databases, for example, will cause a flood in traffic that affects network performance. It is also possible to overwrite other people's changes to group policy in AD, which Thompson said could run contrary to an enterprise's security policy.

"These problems are not easily fixable - they are design issues," said Thompson, who added that Microsoft will have to rework the product to fix these problems and that this can not be expected until the release of Whistler, Microsoft's next full-version upgrade.

This is expected by Gartner in the fourth quarter of next year, but users are likely to become entangled in design issues with AD later this year or early next. This is because roll-outs of Microsoft Exchange will present the first compelling reason to deploy AD.

"So far, most companies are just dabbling with AD and have not got into these problems," said Thompson. "These problems have only been seen by joint development partners, and companies who got into it fast. Most users will bump into these issues at the point when they have Exchange roll-outs."

Nick McGrath, W2K product manager at Microsoft, said: "Amongst the many mainstream customers I come across, I've not come across this issue."

Pressed on the design problems highlighted by Gartner, he said that he was not aware of them and expressed confidence that organisations who plan AD deployment properly would be successful.

McGrath said that a number of companies have already deployed AD, although he declined to say which, and that successful deployment depends on planning and design. He said to get the most of W2K, organisations would have to roll out AD, and provided this was successfully planned, users would not hit any significant problems.