EVPN FAQ

What is EVPN?

Ethernet VPN (EVPN) is a new technology that is used to extend Ethernet circuits across Data Center and Service Provider networks. It is expected to succeed other L2VPN transport methods such as BGP-based L2VPN (RFC6624), LDP-Based L2VPN (RFC4906) and VPLS.

EVPN introduces a set of new features that were not available in L2VPN and VPLS environments, most noticeable of which are All-Active Multi-homing across multiple PE devices and more efficient handling of L2 Multicast traffic.

Refer to RFC 7209 to better understand the rationale for creating EVPN.
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EVPN Type 6 (Selective Multicast Ethernet Tag Route) Explained

EVPN Type 6 (Selective Multicast Ethernet Tag Route) Explained

EVPN Type 6 Route is defined in IGMP and MLD Proxy for EVPN IETF draft. The purpose of this route is to distribute Host’s or VM’s intent to receive Multicast traffic for a certain Multicast Group (*,G) or Source-Group combination (S,G).
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Need for IGMP and MLD Proxy in EVPN Environment

Section 16 of EVPN RFC7432 defines the mechanism for forwarding multicast traffic within EVPN networks. Ingress Replication and/or P2MP LSPs may be used for Multicast forwarding. The major shortcoming of Multicast forwarding approach defined in RFC7432 is the lack of per-group multicast trees, meaning that Multicast traffic is getting forwarded to all PE devices participating in a given EVPN instance, regardless of presence of interested receivers.
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EVPN Route Types

Route Type Description RFC Route Type Explained
0 Reserved RFC 7432
1 Ethernet Auto-Discovery (A-D) route RFC 7432 EVPN Type 1 Explained
2 MAC/IP advertisement route RFC 7432 EVPN Type 2 Explained
3 Inclusive Multicast Route RFC 7432 EVPN Type 3 Explained
4 Ethernet Segment Route RFC 7432 EVPN Type 4 Explained
5 IP Prefix Route draft-ietf-bess-evpn-prefix-advertisement-04 EVPN Type 5 Explained
6 Selective Multicast Ethernet Tag Route draft-ietf-bess-evpn-igmp-mld-proxy-00 EVPN Type 6 Explained
7 IGMP Join Synch Route draft-ietf-bess-evpn-igmp-mld-proxy-00 EVPN Type 7 Explained
8 IGMP Leave Synch Route draft-ietf-bess-evpn-igmp-mld-proxy-00  EVPN Type 8 Explained
9 Per-Region I-PMSI A-D route draft-ietf-bess-evpn-bum-procedure-updates-01
10 S-PMSI A-D route draft-ietf-bess-evpn-bum-procedure-updates-01
11 Leaf A-D route draft-ietf-bess-evpn-bum-procedure-updates-01
12-255 Unassigned

 

EVPN MPLS Port-Based VLAN-Aware Bundle Service

In this article, we will review EVPN MPLS Port-Based VLAN-Aware Bundle Service  configuration example using Juniper MX devices. As per Port-Based VLAN-Aware service definition in RFC7432, all of the VLANs on the port are part of the same service and are mapped to a single bundle without any VID translation.

EVPN VLAN-Aware Bundle Service
EVPN VLAN-Aware Bundle Service

In our sample, we will add L3 IRB interfaces to VLANs, simulating L3 Default Gateways.
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Inter-subnet routing in EVPN MPLS Environment

In this article, we will review inter-subnet routing scenarios in EVPN environment. As we will discover, certain topologies might lead to sub-optimal traffic flows within EVPN network.

Our setup will be comprised of three PE and four CE devices as shown below:

Inter-subnet routing in EVPN Environment
Inter-subnet routing in EVPN Environment

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Hot Potato vs Cold Potato Routing

Hot Potato and Cold Potato are two practices of exchanging traffic between BGP Peers. The difference in these two methods is in the approaches to how to carry traffic across the network.

Hot Potato vs Cold Potato discussions are only relevant in the scenarios where multiple traffic exchange (peering) points exist between two networks.

In our example, we will use the following diagrams depicting two networks spanning across North America and Europe.

We are interested in the traffic flow that is originated by Customer-NA connected to ISP-BLUE and is destined to Customer-EU connected to ISP-GREEN.

BGP Hot Potato vs Cold Potato Routing
BGP Network Interconnects

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EVPN Type 5 Configuration Example – Juniper MX

Introduction

In this example, we will show how to configure L2 and L3 EVPN service on Juniper MX devices.

If you are not familiar with EVPN, please review our introductory articles on EVPN.

In this lab, we will leverage our previous example, where we delivered L2 connectivity between multiple sites, and will augment it with L3 site-to-site connectivity options.

One shared broadcast domain with IP range 1.1.1.0/24 is used on PE-CE interfaces across the entire network. Each CE site is assigned a unique subnet on LAN interface.

EVPN Type 5 Lab Topology
EVPN Type 5 Lab Topology

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EVPN Type 5 (IP Prefix Route) Explained

EVPN Type 5 route that is proposed in ‘IP Prefix Advertisement in EVPN’ draft is a mechanism to carry IPv4 and IPv6 advertisements in EVPN-only networks. While EVPN Type 2 routes allow to carry both MAC addresses and IP addresses, tight coupling of specific IP addresses with IP Prefixes might not be desirable. Section 2.2 of the draft discusses different scenarios where such coupling is nor desirable.

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