Network equipment maker Juniper Networks is acquiring Netscreen Technologies in an all-stock deal worth approximately $4 billion (£2.15bn), according to a statement Juniper released Monday.

The acquisition will add NetScreen's network security products, including firewalls and VPN (virtual private network) technology, to Juniper's portfolio of high-end networking products. Both companies are based in Sunnyvale, California.

The addition of Netscreen's technology will help Juniper better serve its customers by addressing network security concerns, in addition to reliability and performance, said Juniper CEO Scott Kriens in the statement.

The deal is expected to close in the second quarter of 2004 and must be approved by the shareholders of both companies.

In a conference call to discuss the agreement, Kriens called the deal a "game-changing day" in the networking world.

The deal presents new opportunities for the combined company to reach large customers who are the focus of both NetScreen and Juniper. Netscreen's traditional strength in large enterprises will mesh well with Juniper's historical focus on Internet service providers, ILECs (incumbent local exchange carriers) and the defence industry, Kriens said.

At the same time, he dismissed the focus on those traditional market distinctions. The growth of networked devices, from portable digital assistants to home entertainment systems is blurring the line between public and private networks, Kriens said. The future will be less about focusing on specific markets than about ensuring the quality and security of data sent from source to destination.

NetScreen's 900 employees will join Juniper's staff of 1,600 in a new security products group under NetScreen President and CEO Robert Thomas, who will report to Kriens. That group's initial focus will be on meeting the demands of NetScreen's existing customers. However, the two companies will look at ways to "cross pollinate" their technology and intellectual property, Kriens said.

Together, Juniper and NetScreen will combine their technologies into suites of products that combine core IP routing with security and policy management features, extending the reach of security products from the network perimeter to the "heart of the network".

Kriens contrasted that with the approach taken by leading competitors such as Cisco Systems Inc., which relies on plug-in components, or "blades", to add security features to networking hardware.

Executives from both companies expressed enthusiasm for the deal Monday. Speaking on the conference call, NetScreen's Thomas said executives at his company are "almost delirious" at the prospect of joining with Juniper.

Besides the combined resources of the two companies, NetScreen executives look forward to getting access to channels, such as Internet service providers, where Juniper is a strong player, he said.

In recent months, NetScreen has been taking steps to increase the breadth of its security offerings. The company bought SSL (Secure Sockets Layer) VPN maker Neoteris Inc. of Mountain View, California, in November for $265 million (£143m) in stock and cash, to add that popular remote access technology to its portfolio.