In BitTorrent, suppose Alice provides chunks to Bob throughout a 30-second interval. Will Bob necessarily return the favor and provide chunks to Alice in this same interval? Why or why not? What is an overlay network? Does it include routers? What are the edges in the overlay network?

It will not necessary that bob will provide chunks to Alice.

Explanation:

Alice has four neighbors of Bob so he will send message to her, but this might not occur if Alice provides chunks to Bob.

Overlay is the network that build at the top of other network. It is a telecommunication network that supported by its own infrastructure.

It encapsulates one packet inside an other packet.

It is a method of creating layers of network that can be used to run multiple virtualized layers on the top pf other network.

It provides new security benefits.

Does Overlay include Routers

Overlay is a file sharing system in which nodes participating and create logical links between them. So overlay network does not include routers.

Edge in overlay

It is a logical network in which nodes are connected using virtual or logical links.