An Alien wave comes in from an external source, for an example a customer has WDM optics in their kit. A normal wave the “customer” connects with a normal 10GE/100GE (or whatever is appropriate) and a line card on the OTN platform “grooms” that to the appropriate WDM channel.

From: NANOG <nanog-bounces+tony=wicks.co.nz@nanog.org> On Behalf Of TJ Trout
Sent: Wednesday, 14 October 2020 6:22 am
To: James Jun <james.jun@towardex.com>
Cc: nanog <nanog@nanog.org>
Subject: Re: Passive Wave Primer

What is the difference between a normal wave and a alien wave?