Gfrktyl

As shown in the attached picture, I wish to draw that red arc between the left node and the right node and label it as ABC (shown in attached image).

How can I do it?
The code that I have worked out till now is given as follows:

 begin{tikzpicture} 

 begin{scope}[minimum width=15mm,minimum height=10mm]

 node[draw,line width=0.25mm,rounded corners, label= 

 {[align=center]above:ABCD\ abcdefgh 123 \mnopqr}] (v1) at (0,0) {$G_F(s)$};

 node[draw,line width=0.25mm,rounded corners, label= 

{[align=center]above:mnomno \ xyzxyzxyz}] (v2) at ($(v1)+(10,0)$) {$R(s)$};

 node[draw,line width=0.25mm,rounded corners, label={[align=center]below: \ abcdef integer\abcedef}] (v3) at ($(v1)+(5,-4)$) {$G_{I}(s)$};

  end{scope}

  draw[->] (v1) -- (v2) node[pos=0.5,sloped,above]{ABCDEF 

approach}node[pos=0.5,sloped,below]{textcolor{red}{textbf{Proposed 

approach}}};

      draw[->] (v1) -- (v3) node[pos=0.5,sloped,above]{Approach 1}; ;

  draw[->] (v3) -- (v2)node[pos=0.5,sloped,above]{Approach 2};

 end{tikzpicture}

You can specify a /tikz/to path style and do something like draw (v1) to[my style] (v2) or a simpler solution:

documentclass[border = 5pt]{standalone}



usepackage{tikz}

usetikzlibrary{calc}





begin{document}

begin{tikzpicture}

  begin{scope}[minimum width=15mm,minimum height=10mm]

 node[draw,line width=0.25mm,rounded corners, label=

 {[align=center]above:ABCD\ abcdefgh 123 \mnopqr}] (v1) at (0,0) {$G_F(s)$};

 node[draw,line width=0.25mm,rounded corners, label=

{[align=center]above:mnomno \ xyzxyzxyz}] (v2) at ($(v1)+(10,0)$) {$R(s)$};

 node[draw,line width=0.25mm,rounded corners, label={[align=center]below: \ abcdef integer\abcedef}] (v3) at ($(v1)+(5,-4)$) {$G_{I}(s)$};

  end{scope}

  draw[->] (v1) -- (v2) node[pos=0.5,sloped,above]{ABCDEF

approach}node[pos=0.5,sloped,below]{textcolor{red}{textbf{Proposed

approach}}};

      draw[->] (v1) -- (v3) node[pos=0.5,sloped,above]{Approach 1}; ;

  draw[->] (v3) -- (v2)node[pos=0.5,sloped,above]{Approach 2};



  %% new line

  draw[red] (v1) .. controls ($(v1)+(1,-8)$) and ($(v2)+(-1,-8)$) .. (v2) node[midway, below]{PCB};

end{tikzpicture}

end{document}