The multi-port NIC dilemma


The emergence of 10G Ethernet network interface cards gives network professionals a new tool for getting more bandwidth to servers, but industry observers say some users might find better value for scaling server pipes by installing multi-port Gigabit NICs.

Until 10G prices come down - and they are expected to - users can save almost 80% by buying multi-port Gigabit cards instead of a single 10G Ethernet card, if bandwidth needs don't exceed 4G bit/sec. High-volume Web/intranet or database servers could be good candidates here, experts say.

But for companies looking for a NIC to move large blocks of data on and off servers - such as network-attached storage devices - 10G NICs might be more versatile.

Intel was the first to market a 10G Ethernet network controller in 2002, and other vendors such as S2IO and Chelsio Communications have since debuted 10G NIC products. These products promise network speeds as high as 5G to 7G bit/sec per connection - because of limitations in operating system software and PCI-X bus speeds - and can be trunked to bring Gigabit speeds in the double digits to some high-end boxes.

The multi-port benefit

But some observers say if a need exists for a 2G to 4G connection, users would be better served by installing multi-port Gigabit cards. These cards offer as many as four 1000Base-T ports on one PCI-X card and can be trunked to create a virtual 4G pipe.

With the cost of 10G NICs in the $2,000 to $5,000 range, multi-port NICs offer a lower price-per-Gigabit cost, with prices about $400 per card.

Made by such vendors as Intel and Syskonnect, four-port NICs also typically run on copper wiring, which is less expensive to install than fiber cabling - a requirement to run 10G Ethernet. More importantly, quad-port NICs don't need a 10G Ethernet port on the other end, as prices for 10GBase-LX switch ports are still in the $7,000 to $8,000 range.

"If you need to go above one Gigabit" on a server connection right now, "it's more cost-effective to go with a multi-port Gigabit card vs. a 10 Gigabit" NIC, says David Newman, president of Network Test, a network equipment testing firm, and a member of the Network World Lab Alliance.

Besides the cost of the equipment, Newman says other factors involved with running a data center play into the decision of whether to go multi-port Gigabit or single-port 10 Gigabit.

"The capital cost of interface [cards] is only one factor," Newman says, "and maybe not the most important factor."

Having to deploy more switch ports to support trunked Gigabit could end up being costly as well and harder to manage than a single 10G port.

"If you've got server farms with 64 of 128 servers and they all have four trunked Gigabit links, you quickly run up your power consumption on the servers, as well as real estate on the switches they connect to," Newman says.

The 10G option

On the other hand, for users of very large servers, 10 Gigabit is becoming the more attractive option.

At the San Diego Supercomputer Center (SDSC), a high-end IBM P-Series is used as a kind of scientific number-cruncher-for-hire. The box lets researches attached to Internet 2 tap into the device for various projects, which puts the server in high demand. The server can accommodate up to 10 interface cards that run Gigabit Ethernet, but trunking Gigabit links did not solve bottleneck issues.

"Aggregating multiple Gigabits is great," says Nathaniel Mendoza, an IT technician at the SDSC. "But you can't get a stream over one Gigabit through," on the trunked connections. Although the server had a total of about five to seven Gigabits of bandwidth, no single flow, such as a file transfer, could exceed 1G bit/sec. This was a problem when the only job the P-Series box had was to move a chunk of data.

Just last week, SDSC installed a 10G NIC from Intel, and the performance boost was immediate. "This gives us the ability to get more data out of the supercomputer more quickly," Mendoza says.

In addition to the flow issue, there is a less technical reason Mendoza prefers the single 10G NICs.

"I don't like running cables," he says. "So I only have to run one cable [when connecting to a 10G NIC on the P-series]. That makes my life significantly easier. . . . Anything we can do to keep down the amount of cables we have laying around is helpful."

Costs can kill

The high price of 10G NICs, compared to what a Gigabit NIC costs, still prevents every server at the SDSC from having its own 10G adapter.

"Cost would be the only reason why I wouldn't put in a [10 Gigabit NIC]," Mendoza says. "But those costs are coming down. Once the 10 Gig E over copper standard is pushed down, it will continue to drop. Optics are still not cheap."

While the cost-per-Gigabit argument right now favors four-port NICs over single-port 10G NICs, that could change quickly. The Dell'Oro Group estimates that 10G NIC prices will drop from an average price of $6,000 per NIC this year to $3,000 in 2007.

The expected price drop in 10 Gigabit, and the development of a Category 6-based copper standard for 10 Gigabit (due in 2006), will make 10G NICs go the way of Gigabit Ethernet cards - less expensive and more widely used, observers say.

"A question people asked in 1997 was, 'So there are lots of good quad-port Fast Ethernet cards out there. Why do we need a Gigabit card?'" Network Test's Newman says.

SDSC's Mendoza agrees with this logic.

"It seems that all the arguments that were made against one Gigabit when that technology emerged are now happening around 10 Gigabit [the requirement of fiber cabling]. Now Gigabit costs almost nothing," he says.

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