EVPN: Ethernet VPNs discussion

EVPN: Ethernet VPNs discussion 


Ethernet VPNs (EVPNs) have become increasingly popular in recent years, offering solutions to various networking challenges. In this blog post, we will delve into the details of EVPN, exploring its route types and how they are applicable in real-life design and deployments.

EVPN: Ethernet VPNs

The Importance of Route Types

BGP EVPN route types serve as the heart and soul of BGP EVPN and VXLAN fabric. Understanding the construction and usage of these route types is crucial for comprehending how the VXLAN fabric operates. While the system may seem complex, it replaces the complexity of spanning tree, resulting in a more efficient network. In this blog post, we will focus on six of the most commonly used route types.

Route Type 2: MAC Advertisement Route

Route type 2 is the most well-known route type in BGP EVPN. It is used for layer 2 switching and allows for the advertisement of locally connected MAC addresses. By using route type 2, MAC addresses can be used to establish connections within virtual networks and create VXLAN fabrics as layer 2 transit networks. This route type is also used for layer 3 connections and aids in reducing Layer 2 broadcast, unknown unicast, and multicast traffic.

Route Type 3: Inclusive Multicast Route

Route type 3 is used for ingress replication, enabling the transmission of layer 2 broadcast, unknown unicast, and multicast traffic over an IP-only network without multicast enabled in the underlying network. In this case, unicast tunnels are established between leaf switches, allowing for efficient forwarding. Route type 3 is especially useful in scenarios where multicast is not available or practical.

Route Type 5: Prefix Route

Route type 5 is a simple prefix route used for advertising locally connected subnets or external subnets from the fabric. It is commonly used for advertising subnet information within the fabric and can be used for advertising external subnets as well.

Route Types 1 and 4: Ethernet Segment Routes

Route types 1 and 4 are used for standard-based Ethernet segment multihoming. They provide a solution similar to Cisco's VPC multihoming but adhere to standard-based protocols. Route type 4, also known as the Ethernet segment route, is used to identify other members of the Ethernet segment connected to the same segment as the advertising switch. It is also used to select the designated forwarder for layer 2 broadcast, unknown unicast, and multicast traffic. Route type 1, or the Ethernet AD route, is used for load balancing and aliasing. It helps balance traffic between multiple devices and provides fast convergence and mask withdrawal.

Understanding the Control Plane

In the control plane, the local virtual tunnel endpoint (VTEP) generates MAC advertisement routes and exchanges them with remote leaf switches. These routes contain MAC and IP address bindings, which are crucial for the functioning of EVPN. The control plane also handles the advertisement and import/export of route targets, ensuring the routes are installed correctly.

Understanding the Data Plane

In the data plane, traffic is routed between virtual networks within the tenant or virtual routing and forwarding instance. This routing is facilitated by the advertisement of host routes within the EVPN control plane. The MAC and IP address information is shared between switches, allowing for efficient forwarding of traffic.

EVPN for Layer 2 and Layer 3 VPN Services

EVPN can be used for both layer 2 and layer 3 VPN services. While it is primarily designed for layer 2 VPNs, it can also be utilized for layer 3 VPN services using route type 5. This allows for flexible deployment options and the ability to tailor the network to specific requirements.

The Benefits of EVPN

EVPN offers numerous benefits, including: 1. Efficient traffic forwarding: EVPN replaces the complexity of spanning tree with a more efficient forwarding mechanism, allowing for faster convergence and reduced broadcast traffic. 2. Scalability: EVPN provides a scalable solution for interconnecting large networks, making it ideal for modern data centers and cloud environments. 3. Multicast and unicast support: EVPN supports both multicast and unicast traffic, allowing for flexible deployment options based on network requirements. 4. Improved network visibility: The use of route types and the control plane allows for improved visibility and control over the network, making troubleshooting and management easier.


EVPN is a powerful solution for modern networking challenges. By understanding the various route types and their applications, network engineers can design and deploy EVPN networks that are efficient, scalable, and tailored to their specific needs. With its ability to handle both layer 2 and layer 3 VPN services, EVPN offers a flexible and versatile solution for modern network environments.

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