Last week I invited Neeraj Malhotra, a Principal Engineer at Cisco, to present at the Bay Area Network Operators Group (BANOG) on how EVPN can be used to build multi-tenant data center fabrics. Neeraj gave a great presentation  and I’m sharing his slides below.

EVPN has many use cases and this presentation focuses on EVPN as a control plane in the data center to support host/VM mobility and active/active multihoming. I’m currently looking at EVPN as alternative to replace the proprietary MLAG technology in my data centers.

The presentation abstract and slides are below. Enjoy.

Abstract:

EVPN-IRB (Integrated Routing and Bridging) is a technology that leverages BGP EVPN as common overlay control plane to enable VPN routing and bridging service over an MPLS or IP underlay fabric. Point to multi-point bridging service enables VLANs to be stretched across data center IP or MPLS fabric, while VPN routing service enables inter-subnet routing across these stretched subnets. It hence allows for flexible workloads with seamless VM mobility across the stretched subnet. 

This talk will provide a tutorial of relevant EVPN constructs and procedures used to enable overlay bridged and routed connectivity between tenant workloads in a data center and compare three main design choices with respect to overlay routing architecture: 
– Centralized EVPN-IRB: with centralized first-hop any-cast GW on the border leafs OR DCI / DC Edge routers
– Asymmetric EVPN-IRB: with distributed first-hop any-cast GW on the ToRs
– Symmetric EVPN-IRB: with distributed first-hop any-cast GW on the ToRs

It will further focus on a symmetric EVPN-IRB design with distributed any-cast GW, and go thru detailed packet walks to get a good feel for how an EVPN-IRB based DC fabric works to provide any to any L2 and L3 overlay connectivity. 


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