The iSCSI Subtext to 10-GigE

Growth in 10-Gbit/s Ethernet rollouts may indicate broader deployment of iSCSI SANs.

Think it's a stretch? Let's start at the top. Industry sources say the popularity of 10-Gbit/s Ethernet WAN links is on the rise among carriers, driven by the need to carry multiple traffic types over links that are cheaper than Sonet.

And a significant element in the traffic mix is on- or off-line storage, which along with video and voice-over-IP, is often forcing carriers to double their available bandwidth annually.

A recent report from Heavy Reading states that not only are carriers moving aggressively toward 10-Gbit/s Ethernet in core networks, but they are being pushed toward 100-Gbit/s Ethernet by enterprise customers, including big content providers, who want Ethernet SANs instead of Fibre Channel ones. (See HR Sees Core DWDM Surge.)

At the same time, the increase in iSCSI deployment is nothing less than dramatic. IDC forecasts compound annual growth in iSCSI SAN revenues to be a whopping 74.8 percent from now through 2010, compared to 4.1 percent for Fibre Channel SANs.IDC program manager Brad Nisbet sees the growth of iSCSI driven in part by virtualization, and he says 10-Gbit/s Ethernet "will be deployed largely to handle the increased storage traffic on the back-end of the virtualized environments" that are under construction in enterprises worldwide.

But it's tough to draw a direct correlation between the growth of iSCSI and the adoption of high-speed Ethernet carrier links, even if folk see one anecdotally. After all, most iSCSI SAN gear doesn't yet support 10-Gbit/s Ethernet.

"I don't see 10-Gbit/s adoption as being driven by storage," says Todd Bundy, manager of global alliances at ADVA Optical Networking. He does claim lots of growth for 10-Gbit/s networks. But large enterprise customers, he says, are just as apt to siphon off storage traffic into an FC SAN as they are to upgrade their LANs from 1- to 10-Gbit/s.

Still, the adoption of optical 10-Gbit/s connections, which vendors say is growing, could reflect the use of Ethernet as a transport for storage, along with voice and video. Unfortunately, it's tough to tell for sure whether this is the case, since optical IP networks mix the traffic types.

"In DWDM networks, traditional SAN extension services over Fibre Channel, Escon, and Ficon continue to drive demand in metro deployments," says Scott Clavenna, chief analyst at Heavy Reading. "Across larger backbone networks, SAN transport is rarely a synchronous service, so most often [it] appears within 10-Gbit/s Ethernet waves, where it is mixed in with other IP-based services.""Storage networking continues to be a large driver for enterprises that are either building their own private optical network or leasing a managed service," states Paul Schoenau, senior sales engineer at Ciena. "I would say that iSCSI is involved in these deployments, but since it is passed to us as GbE or 10 GbE, we often cannot determine whether the traffic is standard LAN or iSCSI."

One thing: There can be little doubt that Ethernet's popularity is up. "We see stronger Ethernet versus Sonet transport over DWDM," says Jonathan Amir, VP of sales for the Americas for Ekinops, an optical networking transport startup based in Paris. "It's all driven by carrier customers, who want Ethernet connectivity and are shying away from ATM, frame relay, and Sonet."

Amir says about 80 percent of Ekinops's customers use 10-Gbit/s Ethernet. He claims Ekinops has installed more than 900 systems in the U.S. and Europe, competing against ADVA, Alcatel/Lucent, Ciena, Cisco, and Infinera.

It's clear that both 10-Gbit/s Ethernet WANs and iSCSI systems are burgeoning. Without drawing direct linkages, the trend toward IP for all traffic types seems clearly delineated.

Mary Jander, Site Editor, Byte and Switch