The Serving Gateway a critical network function in 4G mobile core network
in evolved packet core (EPC).
The SGW resides in the user plane where it forwards and routes
packets to and from the eNodeB and packet data network gateway (PGW).
ANLAV NETWORKS - Serving Gateway
The SGW entity forwards incoming data from the PGW entity to the
eNB entity and outgoing data from the eNB entity to the PGW entity