In this post I will go through the BGP EVPN + VXLAN for Data Center Interconnect with Arista switches. VXLAN provides the ability to decouple and abstract the logical topology by using MAC in IP encapsulation, from the physical underlay network. The VXLAN is describes in the RFC 7348 where you can read more about this technology. The initial VXLAN standard describe a multicast flood-and -learn for the overlay broadcast, unknown unicast and multicast traffic. Such flooding introduces some scalability concerns and to overcome the limitation of the flood-and-learn VXLAN the BGP EVPN can be used as the control-plane for VXLAN. The BGP EVPN has been define as the standard control-plane in the RFC 7432 for VXLAN overlays. The MP-BGP EVPN control-plane provides VTEP peer discovery and end-host reachability information across the fabric. In addition MP-BGP EVPN inherits multitenancy supports with VRF construct.

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Segment Routing L3VPN and TE

In my previous post Segment Routing I described basic concept of SR and how it works from data-plane and control-plane perspective. In this article I am going to focus how SR interact with L3VPN and MPLS TE. To do so I am going to use below network topology with Cisco IOS-XE 16.10.


The L3VPN configuration with SR is no different than traditional MPLS L3VPN deployment apart there is no LDP requirement. The CSR3 is configured as VPNv4 RR and basic VRF configuration is on each PE router.

This is configuration on the CSR1, no fancy stuff just simple VPNv4 configuration for BGP and redistribution connected into the VRF.

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New Year 2019

It’s a new year where new opportunities and challenges can show up on the horizon. It seems like a lot of things is happening around networking so I decide to start my blog, where I can describe new technologies, show some use cases and configuration.

Segment Routing

Segment routing (SR) is describe in RFC 8402 and offer flexible way to provide traffic engineering based on the source routing. With SR there is no longer needs to maintain a per-application and per-flow state, and traffic can obey the forwarding instruction provided in the packet.

SR relies on some extension to the routing protocols ISIS and OSPF. The SR can support any type of control plane such as distributed, centralized or hybrid.

Each control plane model provide different set of capabilities and how instructions are allocated and signaled. In a distributed scenario, the segments are allocated and signaled by IS-IS or OSPF or BGP and each node individually decides how to proceed with a packet.

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