Does E-VPN Spell the End for OTV?

If you are considering how best to do Layer 2 stretch for virtual machine mobility, then you might be considering Overlay Transport Virtualization (OTV). OTV designed by Cisco to offer L2 stretch with what they said was an easy to deploy protocol. It was only available on the Nexus switching product line, which didn’t support VPLS/MPLS. Until recently MPLS/VPLS was Juniper’s recommended technology for network segmentation and Layer 2 stretch, which Cisco also offers on the ASR routers.  We’ve recently announced E-VPN, which is MPLS/VPLS based and brings all of the benefits of VPLS and then some. Cisco has announced E-VPN on the ASR router as well. Now that E-VPN is available, maybe it’s time to consider your best option. Let’s take a look at why OTV isn’t the best choice for VM mobility and why E-VPN is.

Why OTV was Invented
OTV has been in the Cisco’s news announcements, highlighted at Cisco Live and featured in several Cisco blogs. It’s something I’ve been meaning to cover along with my blogs on LISP and VXLAN as these all get discussed together as parts of a complete solution for live VM migration. Cisco first announced OTV on Feb. 8, 2010. Overlay Transport Virtualization is a Cisco proprietary protocol which provides Layer 2 extensions, over IP, to interconnect remote data centers.  Cisco claims that the OTV is a simpler technology than MPLS/VPLS, which is a standards-based and proven technology for network segmentation and Layer 2 Extension.  They said that OTV can be provisioned within minutes, using only four commands, and that it provides increased scalability (however without seeing the independent studies we don’t know if this is true).  It was only offered it only on the Nexus 7000, which didn’t offer MPLS/VPLS technology. With OTV, Cisco pushed yet another proprietary protocol that is not as well proven as standards-based MPLS/VPLS or the newer E-VPN. Cisco supports VPLS on the ASR router so it is curious that they did OTV on the Nexus which doesn’t sit at the right place in the network to do L2 Stretch. The Cisco ASR, like the Juniper MX, is meant to do L2 stretch at the data center edge, not in the data center core where the Nexus switches sit.

Is VXLAN the Answer to the Network Virtualization Question?

Network virtualization is a growing topic of interest and for some good reasons as networks scale to meet the challenges of cloud computing they are running up against VLAN scaling limitations. There have been several network overlay technologies released that seek to address the challenges with network scaling and to enable workload mobility. One of these technologies is VXLAN. It has a few proponents who say that it can meet the requirements for network virtualization. While it sounds good on the surface, it is worth it to take a closer look. With VMWorld happening this week in San Francisco I’m sure that network virtualization will be a hot topic, especially considering the VMware Nicera news, so I thought I’d comment on it and offer some thoughts and options.

The Origins of VXLAN
The VXLAN buzz started during a keynote at VMworld in August 2011, when VMware CTO Steve Herrod announced the Virtual eXtensible LAN protocol, which VMware positions as a technology that “enables multi-tenant networks at scale, as the first step towards logical, software-based networks that can be created on-demand, enabling  enterprises to leverage capacity wherever it’s available. Networking vendors Cisco and Arista are actively promoting VXLAN and have collaborated with VMware to develop and test the technology on their products. Cisco highlighted VXLAN at their Cisco Live user conference again in June 2012 and Arista is demoing it at VMWorld, however with the Nicira announcement VMWare seems to have taken that next step. VXLAN sounds interesting, so let's see how good of an idea it is.