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 fibre 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 10Gbps, 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. It 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 533Mbps. The fastest PCI bus today is the PCI-X, which tops out at 1Gbps. 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,” said PTI Product Manager Hank Heneghan. With Ethernet on the backplane, each slot in a cPCI chassis receives 2Gbps 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 said 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 added. PTI was scheduled to demonstrate its cPCI/PSB system at the Bus and Board conference in San Diego this 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,” said Thomas Nolle, president of CIMI Corp., a technology consulting firm.

Nolle said 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 said.

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

“Speeding up the bus has been an issue addressed before,” said 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 said. 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 2.5Gbps and 6Gbps. 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 said. 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, said he sees cPCI/PSB as more of a carrier technology, but added that 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 said.