Where to cross RX/TX line in fibre optical cabling
I'm in the process of connecting together some sites via optical fibre. The trans-site multimode fibres are terminated with SC jacks on patch panels from where they are patched to the corresponding switch ports.
In order to receive a working connection, the cables need to be crossed at one point to let RX point to TX and vice versa.
Should this cross-connection be made in the transit cable (i.e. between the patch panels) or one of the patch cables between the panel and the switch? Is there a common practice?
Cross on one of your patch cables. You want your installed fiber plant to be labeled correctly at both ends (Strand 1 at Site A = Strand 1 at Site B).
Definitely always the patch panel. The infrastructure, or as OP called it, the transit cable should always be straight through to ensure that there's consistency between the two patch panels. Fiber 1 is Fiber 1, Fiber 2 is Fiber 2, etc.