David Gross writes that, with all the excitement over the new 40 GbE standard, the reality is that line rate is not as important a measure of network capacity as it used to be, especially with multi-gigabit port prices having more to do with transceiver reach, cabling options, and port densities than framing protocol.
Within the data center, which line rate you choose is increasingly falling back in importance to which transceiver you choose, what type of cabling, whether to aggregate at end-of-row or top-of-rack, and so forth. Moreover, as I wrote a few weeks ago, the most power efficient data center network is often not the most capital efficient. So rather than considering when 40 Gigabit Ethernet upgrades will occur, I think it’s more important to monitor what’s happening with average link lengths, the ratio of installed singlemode/multimode/copper ports, cross-connect densities in public data centers, the rate of transition to IPv6 peering, which can require power-hungry TCAMs within core routers, and especially whether price ratios among 850, 1310, and 1550 nanometer transceivers are growing or shrinking. So rather than wondering when 40G will achieve a 3x price ratio to 10G, it’s equally important to consider whether 10G, 1550nm transceivers will ever fall below 10x the price of 10G, 850nm transceivers.