Upvote:2
The answer you seek is here: Bishops Are Successors of the Apostles | General Audience of Pope St. John Paul II [the Great], 8 July 1992.
The Council says: "Thus, as St. Irenaeus testifies, through those who were appointed bishops by the apostles, and through their successors down in our own time, the apostolic tradition is manifested and preserved 1 " (LG 20).
1. St. Irenaeus, Adv. Haer., III, 3, 1; cf. Tertullian, De Praescr., 20, 4-8: PL 2, 32; CC 1, 202