Ample Evangelizes Ethernet

The startup takes a break from OC768 to develop an Ethernet analogue to virtual concatenation

May 28, 2003

3 Min Read
Ample Evangelizes Ethernet

Ample Communications Inc. is introducing a twist on Ethernet-over-Sonet, producing an aggregation trick that the company says can increase the efficiency of Ethernet and pack more users onto a single switch.

The new chip, Harrier, could become the company's cash cow, even though it's an entirely new page in Ample's game plan.

Ample was founded in 2000 to build Layer 1-2 chips for high-end line cards. Its first chips targeted 10-Gbit/s Ethernet and OC192 connections, and its pride and joy was the OC768 Blackbird framer released last year (see Ample Crams in the Ports).

Like many companies targeting high-end metro and core markets, Ample found itself looking for new work and decided to tap the activity surrounding Gigabit Ethernet. The resulting chip, Harrier, performs something like virtual concatenation, but for Ethernet streams (see Ample Aggregates Ethernet).

Virtual concatenation allows multiple traffic streams to share a single Sonet pipe -- so that two Gigabit Ethernet streams could share the same OC48 (2.5 Gbit/s) wavelength, for example. The idea is to fill up the OC48 more efficiently, rather than devote it to one Gigabit Ethernet stream and let the remaining 1.5 Gbit/s go to waste (for a more detailed explanation, see PMC Pushes Sonet Silicon).

But what if those Gigabit Ethernet streams are nearly empty themselves? That's the part Ample wants to tackle. Harrier uses oversubscription to try to pack an Ethernet connection more completely.

The Harrier-24 can combine 24 Gigabit Ethernet lines into a single 10-Gbit/s uplink -- a 2.4-to-1 oversubscription. The assumption is that each of those 24 lines is using only a fraction of its potential, something that's almost certainly true in the case of desktop users.

The idea is to reduce the number of line cards needed for aggregating that traffic. "No matter what you're doing, you're doing it inefficiently right now. You've overprovisioned your network," says Vish Akella, Ample's CEO.

Harrier can buffer some overflow traffic if the bandwidth exceeds 10 Gbit/s, but it's conceivable that even the buffer could get overwhelmed. In that case, the chip starts to drop packets, but it tries to apply some justice by identifying which link is responsible for the overflow. "That's the user we start punishing first with drops," says Marek Tlalka, vice president of marketing.

The buffer is a 480-kbyte pool of RAM common to all ports. Most systems assign a buffer to each port, but this approach is more efficient because it allows the memory to be used by whichever port needs it, Ample officials claim.

Ample didn't even conceive of the device until about 10 months ago, when customers began suggesting the concept. But now they're treating the chip like money in the bank, claiming the customers who helped design the part are already committed to buying. "We've got non-cancellable, non-returnable orders," Tlalka says.

Harrier is being targeted at new line cards for existing equipment. The first markets Ample is shooting for are metro installations and large, chassis-based enterprise equipment. But Tlalka sees potential for the idea to get used in core routers and in stackable enterprise boxes, too.

On the carrier side, some networks are already applying this kind of concept. "It's well handled by Ethernet switches today," says Jon Ames, who heads strategic marketing for the service provider division at PMC-Sierra Inc. (Nasdaq: PMCS). "We do some applications where people use Ethernet switches to do some amount of packing, and behind that, one of our mappers," which applies virtual concatenation to put the Ethernet onto Sonet.

Ample still harbors hopes for Blackbird, but for now it appears the company has joined the growing camp of Ethernet converts.

"We are more bullish on this than on any of our other products," Akella says. "You'll see a lot more Ethernet products from Ample."

Harrier comes in three sizes: the 24-port version; a similar 12-port device; and the Harrier-24LS, a 24-port chip for 10- or 100-Mbit/s Ethernet only. The chips are expected to sample next month, at a price of $250 for Harrier-24 and $195 for the Harrier-12 and Harrier-24LS.

— Craig Matsumoto, Senior Editor, Light Reading

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