How can I enlarge space between top node and bottom

I want to make more space between node comm and other nodes. How can I do that? Here's the code:

digraph H {
    overlap="false"
    splines="polyline"
    nodesep=2;
    
 comm [
   shape=plaintext
  
   label=< 
     <table border='1' cellborder='1'>
       <tr><td colspan="3">Коммутатор</td><td port='34'>34</td><td port='36'>36</td><td port='38'>38</td><td port='37'>37</td><td port='40'>40</td><td port='39'>39</td><td port='47'>47</td><td port='48'>48</td><td port='49'>49</td><td port='51'>51</td></tr>
     </table>
  >]; 
con1 [
   shape=plaintext
   
   label=<
     <table border='1' cellborder='1'>
      
       <tr><td colspan="3">Континент 1 </td><td port='In1'>In1</td><td port='8'>8</td></tr>
     </table>
  >];
  con2 [
   shape=plaintext
   
   label=<
     <table border='1' cellborder='1'>
      
       <tr><td colspan="3">Континент 2 </td><td port='In1'>In1</td><td port='8'>8</td></tr>
     </table>
  >];

 comm:34 -> con1:in1;
 comm:36 -> con2:In1;
 comm:49 -> con1:8;
 comm:51 -> con2:8;
}

And it looks like that:scheme

I need to make more space because there will be much more nodes later and they'll placed in the horizontal line on same rank.

Solution

ranksep will alter the distance between ranks.

digraph H {
    overlap="false"
    splines="polyline"
    nodesep=2;
    ranksep=1.6  // spread the ranks
    
 comm [
   shape=plaintext
  
   label=< 
     <table border='1' cellborder='1'>
       <tr><td colspan="3">Коммутатор</td><td port='34'>34</td><td port='36'>36</td><td port='38'>38</td><td port='37'>37</td><td port='40'>40</td><td port='39'>39</td><td port='47'>47</td><td port='48'>48</td><td port='49'>49</td><td port='51'>51</td></tr>
     </table>
  >]; 
con1 [
   shape=plaintext
   
   label=<
     <table border='1' cellborder='1'>
      
       <tr><td colspan="3">Континент 1 </td><td port='In1'>In1</td><td port='8'>8</td></tr>
     </table>
  >];
  con2 [
   shape=plaintext
   
   label=<
     <table border='1' cellborder='1'>
      
       <tr><td colspan="3">Континент 2 </td><td port='In1'>In1</td><td port='8'>8</td></tr>
     </table>
  >];

 comm:34 -> con1:in1;
 comm:36 -> con2:In1;
 comm:49 -> con1:8;
 comm:51 -> con2:8;
}

Giving: