Cisco's IOS prioritises ATM, IP data traffic

Cisco Systems has taken a big step toward differentiated classes of service on its own equipment, announcing this week that its routing software now will extend traffic priority across packet-based and ATM networks.

The latest version of the Cisco Internetwork Operating System (IOS) integrates IP and ATM mechanisms for prioritising traffic, Cisco company officials said.

The software will allow enterprises and service providers to classify some types of traffic above others and maintain that priority from one end to the other of a Cisco combined IP-ATM network.

One analyst said Cisco's breakthrough may benefit some enterprises and service providers, but does not revolutionise the Internet by itself.

"Once you cross domains, it's not going to work," said Mary Petrosky, a principal analyst at, a consultancy in California. "Cisco doesn't own the whole Internet."

With class-of-service (COS) control, enterprises and service providers will be able to make sure business-critical applications run as required under all circumstances by squeezing the maximum amount of network bandwidth that less important traffic can consume.

With this tool, traffic designated as important on a Cisco IP device will also be prioritised on a Cisco ATM switch.

Cisco likened its new IP-ATM COS capabilities to service classes in airline travel, in which business class receives better service than coach, and first-class service exceeds that of business class.

The new capability enables service providers, telephone companies, and geographically dispersed enterprise customers to better manage network resources, as well as gain flexibility to provide a greater quality of service (QOS) for mission-critical traffic, Cisco officials said.

"It's a good step forward for the industry," Petrosky said.

However, Petrosky added, "this is of limited use at this point in time."

Standards will be the key to making QOS work across WANs, and current standards efforts are moving slowly, according to Petrosky.

The Internet Engineering Task Force is currently working on COS mechanisms that will bring together ATM QOS and emerging IP packet-based QOS methods.

The Cisco solution announced last week is limited to devices running IOS, but company officials said the mechanism will permit a phased deployment to Cisco's Tag Switching technology and Multiprotocol Label Switching.

The COS capability is available now for Cisco 7500 series routers. Pricing for the routers has not been disclosed.

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