Norwegian to English Tech/Engineering IT (Information Technology) IT infrastructure

Redundans på lag to ivaretas gjennom oppsett av 4 kjernesvitsjer som er koblet i en ring

Above this line of text is a diagram of the IT infrastructural network of a company, the central part being "kjernering" (core ring?) and Ring 1, 2, 3 etc. The text talks about the redundant servers that "kick in" (for want of a better expression) if the main server goes down.

is "lag to" in this context "second layer"?

TYAIA