HP StorageWorks MSA 2.8 SAN Switch - Manual (Page 140)

Updating Switches to the Core PID Addressing
140 Fabric OS Procedures Version 3.1.x/4.1.x User Guide
Overview
Core PID addressing is an option of the configure command for 2.6.0c + and
3.0.2.g+ firmware, but not 4.x firmware. In a purely 4.x fabric, it is not necessary
to enable Core PID addressing since this is set by default.
However, even if you are configuring a Core Switch 2/64 or SAN Switch 2/32
switch, it is important to note this requirement if you have a fabric that mixes 4.x
switches with other switches. In this scenario, all switches besides the 4.x series
would have to have Core PID addressing enabled. Failing to update the Core PID
addressing in non-4.x switches will result in segmentation in a mixed fabric.
The flowchart in Figure 2 shows a detailed process for adding a new switch into a
fabric.