Breaking Down VPLEX WWPNs

This week I am attending EMC’s VPLEX Design and Deploy class and thus far it has been a very good experience.  I won’t go over what VPLEX is or how it works, but check out Scott Lowe’s blog (here and here) for a detailed overview.  I wanted to share some knowledge that the great Lesky, our quasi course instructor, dropped on us today; what VPLEX WWPNs (worldwide port names) actually mean.  To my surprise they weren’t just a vendor prefix followed by random characters.

So lets start with the WWPN.  The WWPN is a 16 character (8 byte) unique string that represents an individual physical port within a VPLEX engine.  Here is what any given WWPN within a VPLEX looks like:

 

Now let’s break this down piece-by-piece.  The 0x is at the beginning of every WWPN and doesn’t represent anything.  Moving right along to the first 4 bytes, depicted below

As you can see the first 4 bytes are 50001442.  These bytes represent the IEEE OUI, also know as the vendor prefix.  This vendor prefix is actually registered as EMC Invista, which is an older virtual storage product that never really took off.  EMC used the same OUI for VPLEX.  All VPLEX OUIs will be 50001442.

 

The next byte represents which director this port is attached to and the hardware type of the VPLEX engine this port is part of

In this case the byte is 40, which means that this port is a part of Director A on VPLEX VS1 hardware. Here is a breakdown of the possible values you will see at this location

  • 40 – represents Director A on VPLEX VS1 hardware
  • 50 – represents Director B on VPLEX VS1 hardware
  • 60 – represents Director A on VPLEX VS2 hardware
  • 70 – represents Director B on VPLEX VS2 hardware

Currently VS2 is the latest hardware that ships with VPLEX.

 

The next 2 bytes come from the VPLEX engine seed

The engine seed, which is also the wwn-seed, is  4 bytes in length and unique to each VPLEX engine.  The 2 bytes in the WWPN are the last 2 bytes of the VPLEX engine seed to which this port is connected to.

 

The last byte represents two things.  The first part of the byte represents the module on that particular director in that VPLEX engine

In this example, this is module 1

 

The second part of the last byte is the port

The port is port 3, which is located on the module in the first part of the byte

 

Now that we have broken this down, let’s put it all together.  Looking at the entire WWPN of a VPLEX port that you saw in the first part of this post

 

From the screenshot above you can see the WWPN is 5000144240129c13.  See if you can use the information above to describe this port.

  • This is an Invista OUI, which means VPLEX (unless you are one of the 4 people who actually have Invista)
  • It’s running on Director A inside an engine using VS1 hardware
  • The last 2 bytes of the Engine seed are 129c
  • Located in module 1
  • Located on port 3

The form factors for the hardware types have changed from VS1 to VS2 so the layout is different, and therefore the type of VPLEX port this represents (front-end, back-end, WAN and LCOM) will vary between the hardware types.  In this example this WWPN represents a front-end port.  So, port 3 is a front-end port located on module 1 in director A inside an engine with the last two bytes of the seed being 129c running on VS1 hardware.  Simple right?

 

 

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