MARLBOROUGH, MASS. - If 3Com is successful in its next ASIC endeavor, users can expect to get consistent quality of service (QoS) for applications running between Ethernet and ATM networks.
3Com plans to bolster its CoreBuilder and SuperStack switches with new Application Specific Integrated Circuits (ASIC). The processors are designed to ensure seamless QoS among Ethernet end stations connected over an ATM backbone.
Maintaining QoS integrity across networks based on the same media is challenging enough, let alone enforcing QoS across different nets, analysts say.
The ability to deliver consistent QoS across different network media is vital to voice, data and video convergence because guaranteed service quality is the ultimate return on investment for convergence, observers say. If QoS fluctuates between different media types, the result is poor service that negates the other chief benefits of convergence: reduced equipment and service costs.
3Com's plan hinges on switch hardware that can map 802.1p Ethernet priority bits to one of four ATM QoS features - variable, constant, available or unspecified bit rate - at wire-speed, according to sources familiar with the company's work. This hardware is likely to manifest itself in the second half of 1999 as new ATM uplink and core switching modules for 3Com's SuperStack II wiring closet and CoreBuilder 3500 and 9000 backbone switches, sources say.
Sources also say 3Com is making claims that its ASICs can map 802.1p bits to ATM QoS in 150 nanoseconds, which will have negligible impact on switch performance.
3Com declined to comment.
Though 3Com's approach seems practical and straightforward, the proof will be in how easy it is to configure and enforce QoS policies across Ethernet and ATM, says Michael Speyer, an analyst at The Yankee Group in Boston. 3Com plans to enable enforcement through its Transcend management applications, sources say.
Users anticipate no snags in implementing 3Com's Ethernet-to-ATM QoS products.
"The implementation, as far as I can tell, is not going to be a big deal," says Gary Habermann, director of technical resources at Widener University in Chester, Pa. "This is a critical piece to get in place to finish the convergence effort."
Habermann says upgrading the hardware involved will likely be painless because it will be done at the end of Widener's switch life cycle.
3Com may not be the first to map 802.1p to ATM QoS. FORE says it is shipping ATM uplinks on its ESX-2400 and ESX-4800 switches that map 802.1p, IP type of service and other frame- and packet-based QoS techniques to ATM QoS.
"It's nice to hear that other vendors are beginning to implement some class-of-service mechanisms," says Steve Vogelsang, director of technical marketing at FORE. "We were feeling lonely," he says.
Cisco can perform the 802.1p-to-ATM QoS mapping but prefers to work with Layer 3 techniques, such as Differentiated Services and other IP type-of-service bit manipulations, says Paul McNab, manager for systems architecture in Cisco's enterprise line of business. He claims this provides true end-to-end QoS that scales because Layer 3 QoS mechanisms apply to the WAN as well as the LAN.
Cisco is shipping technology that performs Ethernet-to-ATM QoS mapping at Layer 3, McNab says.
3Com chose 802.1p because it won't require expensive Layer 3 switches in wiring closets, sources say. Most Layer 2 switches support the 802.1p standard, and 3Com is a leading vendor of low-cost Layer 2 switches at the edge of LAN backbones.
3Com is proposing three distinct ways to implement the QoS mapping technique:
At the desktop, using the company's network interface cards (NIC) and Dynamic Access policy software.
In the Windows operating system, using Microsoft's Winsock II API.
At the edge switch.
3Com NICs and Dynamic Access software will apply 802.1p tags to traffic after a workstation user signs on to a network and his access privileges are assigned from a policy server.
Winsock II will enable applications to natively signal their 802.1p priorities to the NIC without the intervention of additional software, such as Dynamic Access.
Setting QoS mapping policies at the switch will let network administrators override workstation-assigned QoS if higher-priority traffic requires the same switch port.
For switches that do not support 802.1p-to-ATM QoS mapping but do comply with the ATM Forum's LAN Emulation 2.0 specifications, 3Com will support the LANE User Network Interface 2.0 and User Network Interface 4.0 specifications for signaling QoS connections across an ATM backbone, sources say. This will ensure that traffic priorities are preserved to the destination edge in multivendor environments, they say.
