LinkClient                 // link created as client

	// for testing:
	linkNoRecvSend LinkRole = 1 << 16 // do not spawn serveRecv & serveSend
	linkFlagsMask  LinkRole = (1<<32 - 1) << 16
)

func NewNodeLink(role LinkRole) *NodeLink {
	var nextConnId uint32
	switch role &^ linkFlagsMask {
	case LinkServer:
		nextConnId = 0 // all initiated by us connId will be even
	case LinkClient:
		nextConnId = 1 // ----//---- odd