Overlay Virtual Networking Solutions Overview

2013 was definitely the year of overlay virtual networks, with every major networking and virtualization vendor launching a new product or adding significant functionality to an existing one. Here’s a brief overview of what they’re currently offering:

Slide taken from Cloud Computing Networking webinar


  • The table includes shipping products with publicly-available documentation (VMware NSX is an exception – they still don’t trust us to understand the documentation … but at least you can watch the NSX architecture webinar).
  • One can always implement a gateway between an overlay network and physical world with a multi-NIC VM. Those solutions aren’t listed in the Gateways column.
  • VMware NSX for multi-hypervisors has bare-metal L2 and L3 gateways, VMware NSX for vSphere has VM-based gateways with in-kernel L2 and L3 packet forwarding.
  • Hardware gateways for VMware NSX for multiple hypervisors (using OVSDB protocol) have been announced, but we haven’t seen a GA product yet.
  • Multiple vendors have announced hardware NVGRE gateways, no major vendor has shipped one.
  • Scalability of Hyper-V depends on the orchestration system. I couldn’t find maximum number of managed hosts supported by SC VMM 2012 – earlier versions support up to 400 hosts.
  • I couldn’t find the number of hosts or ports supported by a Contrail controller. Scale-out architecture using controller federation and BGP route reflectors is probably limited by the number of MP-BGP routes supported by the BGP route reflector (Contrail solution uses one VPNv4 host route per VM IP address).

Need help?

If you need help designing your next-generation private or public cloud with overlay virtual networks, get in touch. You’ll also find plenty of details in my virtualization webinars:

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  1. Nexus 1000V does provide L2 gateway for VXLAN to VLAN (in VM or Nexus 1110 form factor) or you can pair it up with CSR for L3 routing/gateway or physical switches.
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