The docking ring is the outer circular structure of Deep Space 9 and Nor-class space stations where starships can dock. The six docking pylons are part of the structure. The docking ring also had cargo bays and mining facilities. (DS9 episode: "Emissary")
In 2372, when a peace conference chaired by the Valtusians was held on Deep Space 9, all of the berths on the docking ring were occupied by ships. (DS9 novel: The Heart of the Warrior)
In 2376, the Androssi were making preparations to install quantum torpedo bays on Empok Nor's docking ring. (SCE eBook: Cold Fusion)