Solution & Method for Identifying Physical Layer Switch Port Connectivity (19-Aug-2009)

Solution & Method for Identifying Physical Layer Switch Port Connectivity

The problem being solved:

There are a number of physical layer switch (PLS) products on the market, eg Apcon and MRV.

These products provide SAN-based facilities with the ability to remotely connect and disconnect

fibre channel links between SAN devices through software, ie without any need to be present at

site and make physical changes to cable connectivity.

These units can accommodate large numbers of connections. Current models support hundreds

of ports.

PLSs may provide a facility to assign electronic "labels" to ports, intended to identify what is

plugged into them, but this is a fairly long manual procedure, and still relies on accurate data. Whilst these products are a great solution to a real problem, they lack some useful "intelligence":

The PLS ports, themselves, can not identify what is connected to them.

Scenario:

When requiring connectivity across longer distances, it is often the case that cables get

routed via patch panels in to trunks - large looms of fibre channel cables - which are then

connected to another patch panel, and so on. Finally, a large bunch of cables arrives at the

PLS, and are plugged in, hopefully, according to plan
Since the PLS can not identify any of the devices plugged into it, the device connectivity

would remain unverified, and a manual record of expectations would be the only reference
On first use, finding an unexpected device attached to a PLS port can result in costly delays,

as the required device's connection would need to be found, in order to complete a

connectivity requirement

Of course, PLS connectivities may not be permanent - The connections made on day one may not

be fixed, indefinitely. From time-to-time, operators may need to move or disconnect devices. or

replace one connection with another or make new device connections. All of these changes need

to be recorded, so that the connectivity of any given PLS port is always known.

From a remote site, the user will be totally dependant upon the site operators for accurate and

up-to-date connectivity information for each port. With up to 288 connections to a single PLS,

that's a lot of information to maintain accurately.

So, the real problem is,

How to non-disruptively get accurate connectivity data for a physical layer switch?

The solution implemented answers this question.

Summary of the solution:

The basic principle is to dedicate one port (GoldenPort) of each physical layer switch (PLS) for

the purpose of identifying the devices attached to all other ports.

A conventional fibre channel switch (FC switch), by its nature, identifies the WWNN and WWPN

of any device plugged into it.

By connecting the GoldenPort from each PLS to a known and dedicated FC switch port (

GoldenSwitch), there is a means o...