Many of the IT shops I’ve dealt with recently have already upgraded to a 10Gb core network, or are well into the planning stages for one. But we as an industry need to reconsider if this is the right time for such an upgrade. This is not a trivial task, both in terms of expense, and potential disruption. Most shops would expect to get five to seven years out of such an upgrade. Many would be surprised to learn that their investment could be out of date in as little as six months.
The issue revolves around Converged Enhanced Ethernet (CEE). Many shops are planning some level of Fibre Channel over Ethernet (FCoE) adoption over the next couple of years, and FCoE relies on CEE. CEE uses three new Data Center Bridging (DCB) protocols:
· 802.1Qbb – Priority-based Flow Control (PFC)
· 802.1Qaz – Enhanced Transmission Selection (ETS)
DCB Capability Exchange Protocol (DCBX)
· 802.1Qau – Congestion Notification (QCN)
The first two protocols in this list are adequate for one or two hops of FCoE traffic, but if you want an end to end FCoE solution, the third protocol (QCN) is critical to manage congestion at the points of oversubscription. Here’s a few facts about QCN:
· QCN requires every device in the data path to support QCN
· QCN is implemented in hardware, not firmware
· Very few (if any) currently shipping products support QCN
This means if you have a vision of running end to end FCoE in your datacenter, you need to wait. Why make a significant investment that’s out of date when it’s implemented? As an interim step we can add some 10Gb capability to existing switches, and deploy rack switches to provide incremental 10Gb capability until products are ready for these new protocols.
According to Gartner analyst Joe Skorupa we should “Plan to maintain separate data center SANs and LANs for at least the next three years.” Solutions like HP’s upcoming FlexFabric1 can take advantage of FCoE to reduce complexity at the network edge, without requiring a major network upgrades or changes to the LAN and SAN before the standards are finalized.