title: How to make a chain randomly
body: <p>I'm implementing a model based on an article. But there is a paragraph that I don't know, what should I do? That paragraph says :</p>
  <pre><code>A flow f ∈ F is a sequence of 
  data packets that are
  generated at expected rate λf 
  and sent from a source to a
  destination node, traversing a 
  sequence of intermediate nodes
  and links in the network. Each 
  flow f has a specified service
  chain of NFs, denoted as
  →S [f] = (S[1][f], S[2]. 
  [f],..., S[J[f]][f]), which 
  is an ordered sequence of 
  required NFs that the flow’s 
  packets must go through, 
  where S[j][f] ∈ V denotes the 
  j-th NF on flow f’s service 
  chain and Jf := |→S [f] | is 
  the length of the NF chain
  of flow f.
  </code></pre>
  <p>I have these information in my code:</p>
  <pre><code>int F = 50;
  Nuflow = 1..F;
  int V = 5;
  Nuvnf = 1..V;
  </code></pre>
  <p>I know λf calculate with log normal with average rate 0.5 and the length of the service chain for each flow is assumed to vary in the range of 2 to 4 NFs and the service types in the chain for each flow are selected randomly.
  I am new in cplex and I don't know how to write code for that parameters. Can you help me? Thanks so much.</p>