VMware NSX – because hairpins are for old ladies

Server virtualization has increased the amount of server to server network traffic, commonly described as east-west traffic. Let’s assume that you have 2 VM’s living on the same host and both VM’s are in different layer 3 networks, in a traditional network traffic flow would be:


essentially “hair pinning” the traffic , meaning the traffic now goes out the VMware host across the network to end up at the same VMware host.

With the NSX distributed Logical Router (DLR) embedded in the VMware kernel the traffic flow would be:


Essentially freeing the external network and using the kernel to move traffic between VM1 and VM2, so now east-west traffic is not externalized and you end up with less hops, less traffic, and more speed.

5 thoughts on “VMware NSX – because hairpins are for old ladies

  1. Besides the fact that this is nice and cool technology, the question to ask is: do you really want the application/system guys to go lower than Layer 7 and inject routes in your precious backbone or do you want the network CLI guys to start using a mouse for “clicking” in vSphere? Which one is the lesser of 2 evils?

    1. I don’t disagree.

      I do believe however that policy based automation is what we are aiming for and the people in charge of those policies will still be the network teams.

      Further down the road the aim should be breaking the IT silo’s, it will be difficult, but it is a goal worth pursuing.

    2. I don’t see it too far off from the old “who manages the load balancer?” debate, systems or network. Self provision-able policy should allow whoever is closer to the application to instantiate policy, not the email that sits in an ops (sysops or netops) inbox for a couple of weeks or worse.

      Either way, good topic. I haven’t seen the DLR running yet. Im curious if other then answering 0x0806 if anything else interesting is happening there. Assuming there aren’t any IGPs running on it, they just receive state from the controller?


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