Those enhancements, security, and voice support are at the top of most customers' lists, according to market leader Cisco Systems. But most customers are adding hardware and software modules to their routers for security functions such as firewalls, intrusion detection, and security accounting, plus other functions such as voice support, virtual private networks, and fault protection, says Rob Redford, VP of marketing for Cisco's router group.

Cisco has new optical modules and other upgrades for its 7600 router, a new route-switch processor and an interface processor for the 7500, and new interface cards for the 7300. The vendor hasn't launched any high-end routing lines recently but continues to offer existing customers new capabilities on a steady stream of new add-on modules, Redford says.

Juniper Networks Inc. makes high-end routers for service-provider and large company networks, both of which demand performance characteristics such as speed, capacity, and resilience, says Kevin Dillon, Juniper's marketing director. Features such as security, traffic prioritization, and quality of service are essential, he says, as are support for multiple IP services such as VPNs, voice over IP, and IP version 6, as well as a choice of interfaces, including multiple varieties of ATM and Ethernet.

Juniper's routers for company networks include its T640 and T320 models. All feature a modular software architecture so that processes, including routing protocols, management, and command-line interfaces, don't interfere with one another. In addition, routing and forwarding functions are separate, so forwarding is performed entirely by application-specific integrated circuits at wire speed without affecting the routing functions.

The big trend is for core routers to perform higher-level functions that depend on traffic characteristics such as transport, session, presentation, and even applications, says Chad Elford, product-line manager of Nortel Networks Corp.'s Passport 8000 and 1000 series routers. With higher-level traffic awareness, "the network is knowledgeable about your request and your user profile and delivers you to the most appropriate site based on those parameters," Elford says.

In the last year, Nortel revamped its entire 8000 and 1000 series high-end Passport routers to include processing capacity for functions such as security and content delivery and awareness. The extra processing headroom is needed because "nobody wants to implement applications such as security if they degrade performance," Elford says.

The trend of upgrading existing routers to achieve desired functions or services ensures that routers will remain a central part of company networks, although it's hurting sales of new routers. Revenue from router sales worldwide dropped 6% in the second quarter of 2002, to $1.5 billion, with, in order, Cisco, Juniper, Avici Systems, and Redback Networks leading in sales, according to Dell'Oro Group, a market-research firm.

High-end router revenue dropped during the quarter, although the number of units shipped remained steady, because increasingly cost-conscious customers shifted from expensive high-speed ports (10 Gbps and 2.5 Gbps) to lower-speed, lower-priced ports (155 Mbps and 10/100 Mbps Ethernet), according to Dell'Oro. Router sales will increase next year, but not much, rising just 1% from $6.8 billion this year to $6.9 billion in 2003, Dell'Oro predicts.

Because most of the new features are add-ons, router vendors "will not get people to replace existing equipment; they're going to wait for extraordinary advances," says Dell'Oro Group founder Tam Dell'Oro, although demand for routed circuits at common T1 speeds is still strong.