![spb protocol spb protocol](https://img.yumpu.com/36864757/1/500x640/data-sheet-skx-linker-ed8-smartop-spbru.jpg)
![spb protocol spb protocol](https://etherealmind.com/wp-content/uploads/2012/05/trill-improves-stp-1.jpg)
Having a single solution (and control plane) that covers all these applications is attractive enough to many service providers who ask for EVPN as their overlay solution however, the strength of EVPN is that it not only provides a single solution in lieu of many disparate solutions but also for any given application, it provides additional features and capabilities that could not have been delivered before because of incapability of other solutions/technologies. These areas include a) point-to-point service for traffic backhauling from customer site to public/private DC network with built-in multi-chassis LAG redundancy, b) micro segmentation of hosts in DC & Enterprise networks, c) IP connectivity among end users (e.g., IP VPN), d) efficient and optimum multicast service for layer-2 and/or layer-3 hosts, e) SD-WAN, f) Data Center Interconnect (DCI), etc.Ī control plane like EVPN or LISP provides a comprehensive and unified solution for all the above use cases which previously could not even be supported by multiple technologies and solutions. The control plane method turned out to be very extensible and flexible, and although EVPN started as layer-2 network virtualization overlay (e.g., layer-2 address learning in control plane), it expanded into many other areas. This was born as the result of short-comings of the first method to address customer needs that could not be addressed via data-plane learning. Via control plane learning such as BGP or LISP SPB w/ ECMP uses this method for overlay network virtualization. It started with Virtual Private LAN Service (VPLS – RFC 4761 & 4762) in 2000 and then re-introduced via VxLAN (RFC 7348) around 2010. This has been around for quite some time. In general, there are two ways to provide overlay network virtualization: Now, let’s look at overlay capabilities of these two technologies. However, when talking about larger networks and integration/interoperability among different networks (e.g., Campus/Branch, DC, SD-WAN, DCI, Public/Private Cloud) having a common fabric technology can certainly be advantageous. Furthermore IP-based fabric is capable of network partitioning via areas and route summarization that don’t exist in SPB w/ ECMP, although one can argue that for small to medium size Enterprise networks, network partitioning may not be required. And although the introduction of IEEE 802.1Qbp (SPB w/ ECMP) added ECMP and transient loop mitigation capabilities to SPB (and more specifically to SPB-M) such that it inherited some IP capabilities in the underlay, a pure IP underlay network has enjoyed continuous incremental enhancements in several active IETF working groups (e.g., LSR, IDR) which continue to still going strong. This enables an EVPN underlay to scale very well. SPB (IEEE 802.1aq) on the other hand was initiated to primarily address shortest-path forwarding. Let’s first look at the underlay aspects for SPB and EVPN. EVPN underlay is based on IP fabric (v4 or v6) which has been around for a long time and its base characteristics are shortest-path forwarding for unicast traffic, Equal Cost Multi-Pathing (ECMP), transient loop mitigation using TTL, and route summarization to name a few. I am also the primary author for majority of EVPN RFCs and drafts including RFC 7432, RFC 7623, and RFC 8365.