Modeling the Internet from the scratch: Link-layer, LAN, Switch - Code snippet: Build network-3

network.go

func Build() (host1 *link.Host, host2 *link.Host, host3 *link.Host,
    swch1 *link.Switch, swch2 *link.Switch) {
    // setup node
    // setup interface
    ...
    // setup link
    link1 := link.NewLink(1)
    attachLink(intf1, link1)
    attachLink(sp11, link1)

    link2 := link.NewLink(1)
    attachLink(intf2, link2)
    attachLink(sp12, link2)

    link3 := link.NewLink(1)
    attachLink(sp13, link3)
    attachLink(sp21, link3)

    link4 := link.NewLink(1)
    attachLink(sp22, link4)
    attachLink(intf3, link4)
    return
}