Cisco bridges IP/ATM gap

Cisco is bridging the quality-of-service gap between Internet protocol and asynchronous transfer mode networks. The router manufacturer is integrating the IP/ATM class-of-service capability into its IOS software and providing class-of-service guarantees throughout a multiprotocol network.

Although Cisco's IOS implements classes of service on IP networks, and ATM has built-in classes of service, "the two are poorly aligned throughout the entire network," said Keith Travis, product line manager of IOS. "We can make more consistent decisions for preserving the traffic class, and we're protecting that all the way through the fabric." Without this capability, service can be guaranteed only within a pure IP or ATM environment.

The software supports six service levels, which are mapped to ATM QOS levels at the packet level. IP/ATM class of service limits those packets that are forwarded immediately, those that are held back and the amount of bandwidth that is available for each class of service. This allows carriers to restrict applications from clogging pipes during peak periods, he said.

"There is a strong need in the service provider space to provide this kind of capability," Travis said. Although service providers often claim guaranteed QOS, that's not always the case, said Tim Smith, principal analyst of wide area networking at Dataquest. "There is no consistent mapping at IP Layer 3 with ATM Layer 2."

The IP/ATM class of service requires a Cisco network on either end of the ATM cloud to provide true end-to-end service level guarantees. It theoretically will work with standard ATM equipment.