VPCS (Virtual PC Simulator)

    LAN ( Local Area Networks)

    VLAN (Virtual LAN)
    https://en.wikipedia.org/wiki/Virtual_LAN
    https://www.techtarget.com/searchnetworking/definition/virtual-LAN

    STP (Spanning Tree Protocol)

    NTP (Network Time Protocol)

    127.0.0.1/8
    loopback interface (lo0)
    Any traffic that a computer program sends on the loopback network is addressed to the same computer.
    The most commonly used Ip address on the loopback network is 127.0.0.1 for Ipv4 and ::1 for Ipv6. The standard domain for the address is localhost.

    https://www.juniper.net/documentation/en_US/junos/topics/concept/interface-security-loopback-understanding.html

    Network address translation (NAT)
    https://en.wikipedia.org/wiki/Network_address_translation

    Open Shortest Path First (OSPF) is a link-state routing protocol
    https://en.wikipedia.org/wiki/Open_Shortest_Path_First