App switch integration boosts blade servers

Blade servers are incorporating LAN switching functions, even application-level switching, as an interconnect between the servers in the blade chassis. While this has the appeal of one-stop shopping, one has to wonder if performance would be any better than it would if you used a separate switch.

It turns out it would, at least according to specific tests conducted in November by the Tolly Group on IBM blade servers.

I recently relayed some Tolly test results – Cisco switches vs. 3Com switches – and received a lot of positive feedback from readers who found the tests useful. (By the way, Cisco indicated to me that it felt it hadn’t participated in the testing, but I never received a formal complaint disputing the results. If I do, I’ll be sure to let you know.)

As I mentioned before, Tolly is paid by vendors to conduct specific tests, often comparing those vendors’ equipment to that of rivals. In these latest tests, IBM’s blade servers were pitted against HP’s blades, particularly on the issue of price/performance.

However, I found it more interesting that Tolly compared the performance of the IBM blade server with integrated Layer 2-7 switching against the IBM blade server with an external switch.

With the full, integrated switch, built by Nortel, the IBM eServer BladeCenter with eight blades had a maximum sustained session-per-second rate of 65,000, 63% higher than the other configurations. The other configurations were the IBM server and an HP blade server, both with integrated Layer 2 switching and an external Layer 4-7 switch from Nortel.

It would appear, then, that even if the price of the external application switch and the internal one were the same, you’d be getting more bang for your buck with the internal switch. But IBM is selling the internal version for less than a third of the cost of Nortel’s external version.

Clearly, other blade server vendors will have to offer internal application switches, too, and the Tolly report notes that HP is planning an upgrade to its internal Layer 2 switch to support application switching as well.

The full report will be available soon at http://www.tolly.com – though it wasn’t posted as of this writing.