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Cisco Programmable Fabric Using VXLAN with BGP EVPN

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David Jansen and Lukas Krattiger, authors of Cisco Programmable Fabric Using VXLAN with BGP EVPN LiveLessons, explain how Cisco's BGP EVPN enhances VXLAN encapsulation with Layer 2 and Layer 3 benefits.

Also see this video from TechwiseTV on VXLAN BGP EVPN. This 15-minute internet TV show highlights some important Cisco technologies.

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The virtual extensible LAN (VXLAN) is a frequent topic of discussion with networking customers today. An overlay technology used for network virtualization, VXLAN by itself is only an encapsulation technique for data-plane encapsulation; additional components are needed in order to provide efficient, scalable data-center network fabrics.

Cisco's Programmable Fabric provides an end-to-end solution for data center fabrics using VXLAN for encapsulation. Programmable Fabric enhances encapsulation by using a standards-based multi-protocol BGP (MP-BGP) control-plane to exchange reachability information (see Figure 1).

Figure 1 VXLAN allows easy optimization by designing the underlay, adding a control protocol, and providing routing and bridging.

VXLAN with BGP EVPN provides standards-based encapsulation for both data-plane and control-plane, which enhances forwarding by moving reachability discovery away from Flood and Learn to basing it on control protocols. Leveraging MP-BGP allows us to integrate a multi-tenancy approach, which is very similar to that of MPLS Layer 3 VPNs. In addition to providing Layer 3 communication (routing) , the Internet Engineering Task Force (IETF) extended the BGP EVPN Network Layer Reachability Information (NLRI) to allow Media Access Control (MAC) Layer 2 information to enhance bridged communication as well (see Figure 2).

Figure 2 Standards-based extension to BGP EVPN provides a control protocol for various techniques, including VXLAN, as part of network virtualization overlay (NVO).

Cisco's Programmable Fabric leverages VXLAN and BGP EVPN with several enhancements and benefits specific to the Layer 2 and Layer 3 reachability information.

With VXLAN BGP EVPN, centralized first-hop routing is no longer needed. This improvement eliminates protocol state and optimizes traffic flows by implementing a distributed IP anycast gateway in the data center fabric. It also reduces the failure domain, with flood mitigation and scalability improvement through disaggregation being some of the attributes following this scale-out model (see Figure 3).

Figure 3 VXLAN with BGP EVPN provides efficiency in forwarding and multi-tenancy.

Data center efficiency, scaling, and optimal traffic flows in the data center are not the only requirements. Provisioning thru programmability and automation are equally important, and shouldn't be left as an afterthought. Cisco's Programmable Fabric combines efficient infrastructure paired with programmability and automation using open APIs.

Summary

Cisco's Programmable Fabric provides a data center fabric infrastructure and spans across the whole Nexus portfolio, with shipping software on Nexus 9300/9500 and Nexus 7000/7700 today.

Cisco's nexus switching portfolio integrates visibility and automation tools for its network virtualization infrastructure (based on VXLAN with BGP EVPN). These advantages are provided through the wide capabilities of the Cisco NX-OS integrated APIs and the resulting extensions to integrate into virtual machine managers, IT automation, or cloud orchestrators such as OpenStack.

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