title: Fluentd: How to solve fluentd forward plugin error?
body: <p>I'm trying to transfer log from one server(A) to another server(B) using fluentd.
  I use forward_output plugin in A and use forward input server in B, but I got there following error.</p>
  
  <pre><code>2017-10-26 16:59:27 +0900 [warn]: #0 [forward_output] detached forwarding server 'boxil-log' host="xxx.xxx.xxx.xxx" port=24224 hard_timeout=true
  
  2017-10-26 17:00:43 +0900 [warn]: #0 [forward_output] failed to flush the buffer. retry_time=0 next_retry_seconds=2017-10-26 17:00:44 +0900 chunk="55c6e86321afbab5bed145d53e679865" error_class=Errno::ETIMEDOUT error="Connection timed out - connect(2) for \"xxx.xxx.xxx.xxx\" port 24224"
  
  2017-10-26 17:01:42 +0900 [warn]: #0 [forward_output] failed to flush the buffer. retry_time=6 next_retry_seconds=2017-10-26 17:01:42 +0900 chunk="55c6e86321afbab5bed145d53e679865" error_class=Fluent::Plugin::ForwardOutput::NoNodesAvailable error="no nodes are available"
  </code></pre>
  
  <p>This is the code for output in A.</p>
  
  <pre><code>&lt;match system.*.*&gt;
    @type forward
    @id forward_output
  
    &lt;server&gt;
      name boxil-log
      host xxx.xxx.xxx.xxx
      port 24224
    &lt;/server&gt;
  &lt;/match&gt;
  </code></pre>
  
  <p>This is the code for input in B.</p>
  
  <pre><code>&lt;source&gt;
    @type forward
    @id forward_input
  &lt;/source&gt;
  </code></pre>
  
  <p>I want to know the meaning of this error, the reason I got this and the way solving this.
  Thank you.</p>