title: AWS and ELB Network throughput limits
body: <p>My site runs on AWS and uses ELB</p>
  
  <p>I regularly see 2K con-current users, and during these times, requests through my stack would become slow and take a long time to get a response (30s-50s)</p>
  
  <p>None of my servers or database at this time, would show significant load.</p>
  
  <p>Which leads me to believe my issue could be related to ELB. 
  I have added some images of a busy day on my site, which shows graphs of my main ELB. Can you perhaps spot something that would give me insight into my problem?</p>
  
  <p>Thanks!
  <img src="https://i.stack.imgur.com/mw7ec.png" alt="ELB Image 1">
  <img src="https://i.stack.imgur.com/4C6bZ.png" alt="ELB Image 2"></p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>The ELB in the screengrabs is my main ELB forwarding to multiple varnish cache servers. In my varnish vcl I would send misses for a couple of URL's but varnish have a queing behavior and what I ended up doing was set a high ttl for these request, and return hit_for_pass for them. What this does is let varnish know in the vcl_recv that these requests should be passed to the back-end immediately. Since doing this, the problem outlined above has completely been fixed</p>