Which one is the real Bosphorus?

[Geticus]

That is at odds with your explanation of Bosporos as Oxford because -ford- does not derive from phero. (Poros derives from poreuo [to make/let go]/poreuomai [to make yourself go i.e. to travel] and associated forms such as poreuteos [to be traversed].) Clearly an entirely different etymology. I am inclined to agree that Bosporos is a kind of Oxford, though. (Still, it need not be a ford to be a poros: a poros might also refer to e.g. a mountain passage).

But as I mentioned there is the possibility that Bosphoros (with -ph-) means something different, e.g. cow-yielding/bearing (bringing forth cows) or similar. This would then possibly be a reference to territory particularly well-suited for herding cattle: i.e. lush grassy plains [without many big predators].

Finally note that bous is not neccesarily a bull, more commonly bovine cattle in general (it is bovus in Latin): the English word for bull is more clearly represented by tauros.

Ok poros from poreuo rather than pherein sounds better. Good point. Though it doesn't much change the meaning since poreuein and pherein have related usages. Are the two verbs etymologically totally unrelated? I don't know and you don't either. Wouldn't surprise me at all to see a PIE radical that fits both verbs.

I like the poreuo etymology better than your "cow yielding" point. The sense of "carry accross/convey" seems to me obvious.

For the record I dragged the "oxford" translation form Liddell & Scott, I claim no originality.