On “VMware’s SDN Dilemma: VXLAN or Nicira?”

Some commentary on a blog published by Networking Computing titled “VMware’s SDN Dilemma: VXLAN or Nicira?”

VMware has a technology problem: it’s backing two competing standards for overlay networks: Nicira’s STT and the IETF draft standard VXLAN

Nonsense.  As of right now, STT tunneling provides the best performance for network virtualization (wire speed).  If and when VXLAN (or some derivative) becomes the best option, it’s just a matter of adding VXLAN as another choice of tunneling protocol from which to configure the system – if not already there.  That’s not a “technology problem”.  That’s providing the right tools at the right time — facilitating a transition from one generation to the next (from early adopters to wide-spread deployment).

… limited entropy in the STT header means it doesn’t balance loads evenly over Ethernet port bundles in network backbones. Depending on your network design, this could be a significant limitation.

This is just factually incorrect.  The TCP source port in the STT outer header is derived from a hash of the internal frame’s header.  Individual flows carried by STT will have a different TCP source port in the other header.  This provides maximum flow level granularity (entropy) for optimal load balancing for ECMP/LAG paths on standard hardware in the physical network.  This is discussed in section 2.5 of the STT informational draft. By the way, this is the same method employed by VXLAN.

NVGRE is the tunneling protocol (pushed by Microsoft) with poor handling of flow level granularity.  Section 4.8 of the NVGRE draft states that “NVGRE-Aware” network devices would be required to realize the best flow level entropy and optimal load balancing on ECMP/LAG paths. Perhaps the author confused STT with NVGRE?