Vendors pushing Ethernet as computer bus option

"Ethernet everywhere" has become a buzz phrase as the technology infiltrates almost every aspect of networking - from LANs to wireless to long-haul fiber optics.

Now a group of equipment manufacturers is looking to push the macrocosmic network standard into the microworld of computer bus technology.

Ethernet as a bus technology could mean faster server and PC buses. With Ethernet speeds approaching 10G bit/sec, PCs and servers have become the bottleneck in networks because their system buses can handle a maximum of only one gigabit of data.

Performance Technologies Inc. (PTI), an OEM component maker for telecom equipment vendors, is developing Ethernet switches on a single CompactPCI (cPCI) card that run over a backplane with an embedded Ethernet layer used as the bus transport technology. The company is calling this technology cPCI/Packet Switched Backplane and has joined with engineers from 37 manufacturing companies to propose cPCI/ PSB to the PCI Industrial Computer Manufacturers Group (PICMG) for standardization.

CPCI is a variation of the PCI bus standard used in PCs and servers. CPCI lets the 20 modules in a standard 19-inch cPCI chassis be hot-swapped without shutting down the device - something not possible in PCI-based devices. Network equipment based on cPCI is popular with carriers because it is reliable and compact.

The maximum speed of the cPCI bus is 533M bit/sec. The fastest PCI bus today is the PCI-X, which tops out at 1G bit/sec. Both bus technologies are shared, meaning that cards on the bus must contend for a fixed level of bandwidth.

"With switched Ethernet embedded on the [cPCI] backplane, we're moving from a shared to a switched bus technology," says PTI Product Manager Hank Heneghan. With Ethernet on the backplane, each slot in a cPCI chassis receives 2G bit/sec of dedicated bandwidth.

One of PTI's products is a carrier-class chassis used for IP voice gateways. Switch fabric cards in one of two slots control traffic for the other "node" slots, which include server cards, speech processing cards and WAN interfaces. Heneghan says this configuration is like crunching a rack of servers and switches connected with network cables into a single box. Instead of Category 5 wiring, the network is an embedded circuit board. This makes the system more reliable and saves space, he adds. PTI will demonstrate its cPCI/PSB system at the Bus and Board conference in San Diego next month.

One industry expert finds it hard to believe that Ethernet as a bus technology will take off.

"There is not a compelling reason to put Ethernet on a cPCI bus," says Thomas Nolle, president of CIMI Corp., a technology consulting firm.

Nolle says bus technology is a mass-market game, and that innovators must have large plans with lots of support from vendors to be successful. "You've got to have a huge market in mind if you're going to do things like this. It's premature for us to presume a market for [Ethernet-based cPCI] will be that big," he says.

Additionally, cPCI/PSB is already behind other efforts to increase PC I/O.

"Speeding up the bus has been an issue addressed before," says Frank Hom, new products development manager with APW Electronic Solutions, an OEM network component vendor. Hom is also on the PICMG executive committee.

"Technologies such as InfiniBand and Serial I/O have been out there for a while," he says. InfiniBand, in particular, has gained momentum from large hardware manufacturers such as IBM and Intel.

The technology promises a switched bus architecture and throughput speeds between 2.5G and 6G bit/sec. Still, InfiniBand products are not expected to be released until late 2001.

"Ethernet protocols are well known, and it's a widely understood technology," Hom says. As a result, the cPCI/PSB concept may have a fighting chance at leapfrogging other I/O boosting technologies in terms of acceptance by manufacturers.

Rajan Kapoor, an analyst with Network Strategy Partners, sees cPCI/PSB as more of a carrier technology, but says it could play a role in corporations down the road.

"As we see more IP voice solutions being deployed, you'll see enterprises requiring this type of architecture," he says.

Kapoor adds that vendors could take advantage of the architecture by installing an entire server farm in one box.

"Enterprise applications for this will not just be in voice," Kapoor says. "This architecture could be used with other applications that require high bandwidth and availability," such as streaming video server farms or server clusters running bandwidth-intensive database applications.

While Ethernet LAN and WAN switches might seem like another logical application for an Ethernet-based system bus, one vendor says this is not the case.

"I'm not sure what Ethernet on the bus level translates to," says Marshall Eisenberg, director of product marketing at Foundry Networks. He believes his company would not use Ethernet as the bus technology in an Ethernet switch.

"Every [switch] vendor wants to do something different to provide more capacity," Eisenberg says. "The idea of standardizing on Ethernet for your chassis and backplane doesn't make sense."

The proprietary backplane and switching fabrics that vendors develop help differentiate them from competitors, he says. He also says most proprietary switch backplanes provide bandwidth that is more than 10 times the capacity of the proposed speed of cPCI/PSB.