While the prayer is a unified whole, it is usually outlined in 3 or 4 subsections, based on whom Jesus is praying for.
Some distinct subsections seen by some commentators are vv.
Throughout the farewell discourse, Jesus has been teaching the disciples about the future, yet in this chapter, he does not entrust the church's future to the church, but to God. In essence, Jesus is praying for the success of the community's work in the world. Jesus prays for the success of our witness in the world. Verse 21 contains three hina clauses, which usually denote purpose or result. I think that each clause is dependent upon the previous clause.