title: how is cluster IP in kubernetes-aws configured?
body: <p>I am very new to kubernetes and have just got a stock kubernetes v.1.3.5 cluster up on AWS using kube-up. So far, I have been playing around with kubernetes in understanding it's mechanics (nodes, pods, svc and stuff). Based on my initial (or maybe crude) understanding , I had few questions:</p>
  
  <p>1) How does routing to cluster IP work here (i.e in kube-aws) ? I see that the services have IPs in the range 10.0.0.0/16. I did a deployment with rc=3 of stock nginx and then attached a service to it with Node Port exposed. All works great! I can connect to the service from my dev machine. This nginx service has a cluster IP of 10.0.33.71:1321. Now, if I ssh into one of the minions(or nodes or VMS) and do a "telnet 10.0.33.71 1321", it connects as expected. But I am clueless how this works, I couldn't find any routes related to 10.0.0.0/16 in the VPC setup by kubernetes. What exactly happens under the hood here that results in a successful connection for app like telnet? However, If I ssh into the master node and do "telnet 10.0.33.71 1321", it does not connect. Why does it fail to connect from master?</p>
  
  <p>2) There is a cbr0 interface inside each node. Each minion node has cbr0 configured as 10.244.x.0/24 and master has cbr0 as 10.246.0.0/24.
  I can ping to any of the 10.244.x.x pods from any of the nodes(including master). But I am not able to ping 10.246.0.1 (cbr0 inside master node) from any of the minion nodes. What could be happening here? </p>
  
  <p>Here's the routes set up by kubernetes in aws. VPC.</p>
  
  <pre><code>Destination     Target
  172.20.0.0/16   local
  0.0.0.0/0       igw-&lt;hex value&gt;
  10.244.0.0/24   eni-&lt;hex value&gt; / i-&lt;hex value&gt;
  10.244.1.0/24   eni-&lt;hex value&gt; / i-&lt;hex value&gt;
  10.244.2.0/24   eni-&lt;hex value&gt; / i-&lt;hex value&gt;
  10.244.3.0/24   eni-&lt;hex value&gt; / i-&lt;hex value&gt;
  10.244.4.0/24   eni-&lt;hex value&gt; / i-&lt;hex value&gt;
  10.246.0.0/24   eni-&lt;hex value&gt; / i-&lt;hex value&gt;
  </code></pre>