{"id":1840,"date":"2023-10-06T13:00:19","date_gmt":"2023-10-06T13:00:19","guid":{"rendered":"https:\/\/blogs.infoblox.com\/?p=8934"},"modified":"2023-10-06T13:00:19","modified_gmt":"2023-10-06T13:00:19","slug":"ipv6-only-in-evpn-vxlan-fabrics","status":"publish","type":"post","link":"https:\/\/ddi.mohflo.net\/index.php\/2023\/10\/06\/ipv6-only-in-evpn-vxlan-fabrics\/","title":{"rendered":"IPv6-only in EVPN-VXLAN Fabrics"},"content":{"rendered":"
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Many organizations are migrating away from traditional three-tier, spanning-tree datacenter and campus LANs to the newer EVPN-VXLAN architecture. This architecture is very flexible and allows for numerous implementation design options, however, the most common deployment is a leaf-spine, or Clos<\/a><\/strong>, design \u2013 so much so that leaf-spine EVPN-VXLAN LANs are the new de facto standard for datacenter and campus LANs alike.<\/p>\n

There are many benefits to EVPN-VXLAN designs, including scalability, optimization for east-west traffic, virtual machine mobility, easier segmentation, simpler automation, all links are active, etc. (This article is not a tutorial on EVPN-VXLAN, but here is a link to a good overview<\/a><\/strong>.) Many of these benefits are related to the fact that EVPN-VXLAN is an overlay on top of a standard, generic, though typically Clos, Layer 3 underlay. Much like MPLS<\/a><\/strong>, the underlay and overlay networks are completely logically separate: What is under the hood, so to speak, is independent from the production traffic flowing over the top.<\/p>\n

Therefore, since the overlay and underlay are separate, the network architect has many options on how to design and deploy the underlying fabric. With this being the case, why not use an IPv6-only \u201cunderlay\u201d to carry your production traffic in the overlay, whether IPv6, IPv4 or dual stack? When EVPN-VXLAN first came out, this may not have been an option. But today, most leading network vendors support (possibly with some limitations) IPv6-only underlay EVPN-VXLAN fabrics.<\/p>\n

First, some terminology<\/h3>\n

When discussing EVPN-VXLAN, it is common to hear the terms \u201coverlay\u201d and \u201cunderlay\u201d tossed around. Before discussing the benefits of IPv6-only, first let\u2019s get on the same page with respect to general terminology and what constitutes IPv6-only. My preferred view breaks EVPN and VXLAN into multiple parts.<\/p>\n

The EVPN-VXLAN underlay is the underlying transport network. Underlay addressing is \u201cinfrastructure\u201d addressing and consists of all fabric switch loopbacks and point-to-point interfaces. A routing protocol is used in the underlay to facilitate the reachability required by overlay protocols. (There are multiple options and combinations for the underlay and overlay routing protocols, e.g., OSPF(v3), iBGP, eBGP, etc., but protocol selection is outside of the scope of this blog.) In summary, the underlay is a base Layer 3 infrastructure.<\/p>\n

The overlay can be split up into three distinct functional planes.<\/p>\n