Other than Cisco’s UCS offering, IBM is currently the only blade vendor who offers a Converged Network Adapter (CNA) for the blade server.  The 2 port CNA sits on the server in a PCI express slot and is mapped to high speed bays with CNA port #1 going to High Speed Bay #7 and CNA port #2 going to High Speed Bay #9.  Here’s an overview of the IBM BladeCenter H I/O Architecture (click to open large image:)

Since the CNAs are only switched to I/O Bays 7 and 9, those are the only bays that require a “switch” for the converged traffic to leave the chassis.  At this time, the only option to get the converged traffic out of the IBM BladeCenter H is via a 10Gb “pass-thru” module.  A pass-thru module is not a switch – it just passes the signal through to the next layer, in this case the Cisco Nexus 5000. 

10 Gb Ethernet Pass-thru Module for IBM BladeCenter

The pass-thru module is relatively inexpensive, however it requires a connection to the Nexus 5000 for every server that has a CNA installed.  As a reminder, the IBM BladeCenter H can hold up to 14 servers with CNAs installed so that would require 14 of the 20 ports on a Nexus 5010.  This is a small cost to pay, however to gain the 80% efficiency that 10Gb Datacenter Ethernet (or Converged Enhanced Ethernet) offers.  The overall architecture for the IBM Blade Server with CNA + IBM BladeCenter H + Cisco Nexus 5000 would look like this (click to open larger image:)

Hopefully when IBM announces their Cisco Nexus 4000 switch for the IBM BladeCenter H later this month, it will provide connectivity to CNAs on the IBM Blade server and it will help consolidate the amount of connections required to the Cisco Nexus 5000 from 14 to perhaps 6 connections ;)