The 10720 Internet Router is Cisco's first IP router targeted specifically at metro networks, where Cisco hopes to make a dent by supplanting some installations of Sonet transport. The system also could be used at the point where an enterprise network interfaces with the metro network, aggregating local-area network traffic in a building or campus for transport to the service provider.

In addition, the company announced a new router and line-card technology for its Cisco 12000 series of core IP routers.

The new Cisco 12404 Internet Router is the smallest of the four 12000 products, taking up just one-eighth of a seven-foot rack but still boasting OC-192 (10-Gbit/s) interfaces. The box is targeted at Cisco's core-networking customers who want to spread IP services toward the edge of the network, said Rob Redford, vice president of marketing for Cisco's public-carrier IP group.

Cisco also announced its IP services engine (ISE) technology, deployed as a set of ASICs on line cards for the Cisco 12000 boxes. ISE is targeted specifically at delivering features such as quality-of-service to the edge of the network.

Analysts have pegged the metropolitan network as the one place where bandwidth is most needed, making it a prime target for equipment vendors facing lean times. Cisco's idea is to let carriers pull more bandwidth from metro rings by converting Sonet-based networks to IP. That shift would remove some of the inefficiencies of Sonet-such as a second ring reserved for emergencies-and IP would allow creation of specialty services such as prioritized bandwidth, Cisco executives argue.

Not all equipment providers are as keen on IP, however. The dispute has aired most prominently in the IEEE 802.17 meetings to develop the Resilient Packet Ring (RPR) standard. Cisco's dynamic packet transport is a candidate for the standard, but a coalition of other participants has drafted a competing proposal concentrating on simpler Layer 2 transport, claiming the costs and complexity of IP are too high for most metro installations.

Cisco contends that IP is necessary in order to differentiate streams of data, which would make possible the types of services the company provides in the network core. More important, the customers already using an IP core are interested in having the same architecture extended to metro networks, Redford said.

"It all depends on the kind of service you're offering," Redford said. Even in a pure Ethernet metro network, "you still have to stick routers on top of that," he said.

The Cisco 12404, the 10720 and the ISE line cards are all shipping.