Mainframe Storage

Hi Arthur, 

You are correct - when using FCIP routers, there is no significant practical difference between longwave and shortwave. I believe that shortwave components are less expensive while longwave components support a much longer fiber cable distance. So, if you're within a few hundred meters between device and FCIP router, it usually comes down to personal preference. Hope that helps. 

Regards,

John 

As John has said whether you use LW or SW for the connection to the director has no bearing on what the connectivity and distance is for the ISLs between the directors

The selection of LW and SW is all about the cabling and optical characteristics of a single cable connection. So you might have a LW connection between the Z server and the FICON director and a SW connection between the DS8000 and the FICON director. 

SW connections support a much shorter cable distance than LW connections and every splice or patch panel in the cable will further reduce the supported distance. So in many cases for Z clients a SW connection will not support the structured cabling and patch panels that clients use. However if the connections are direct between two systems next to each other then SW is perfectly fine.

The Z team has a lot of documentation on this and I've included a link below 

https://www.ibm.com/docs/en/systems-hardware/zsystems/9175-ME1?topic=library-planning-fiber-optic-links