The IPFS Network package handles all of the peer-to-peer networking. It connects to other hosts, it encrypts communications, it muxes messages between the network's client services and target hosts. It has multiple subcomponents:
Conn - a connection to a single Peer
MultiConn - a set of connections to a single Peer
SecureConn - an encrypted (TLS-like) connection
Swarm - holds connections to Peers, multiplexes from/to each MultiConn
Muxer - multiplexes between Services and Swarm. Handles Request/Reply.
Service - connects between an outside client service and Network.
Handler - the client service part that handles requests