What does the end-to-end argument say about networking? Answer: If a problem cannot be fully resolved at a lower layer (or at routers), resolve it at an upper layer (or at end hosts). This pushes...

What does the end-to-end argument say about networking?

Answer:

If a problem cannot be fully resolved at a lower layer (or at routers), resolve it at an upper layer (or at end hosts). This pushes the complexity from core routers to end hosts.

According to the end-to-end argument, at which single layer should we put error control for the Internet? But then why do we put it in many layers including link, IP, and transport layers?

Answer:

At the end-to-end transport layer because both link and nodal errors could be detected and corrected there, i.e., the link layer can only handle the link errors but not nodal errors. But for the purpose of efficiency, error control is also put into the link and IP layers to handle errors earlier.