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 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 MPLS VLAN-Based Configuration

Configuration examples of VLAN-Based EVPN service using MPLS Dataplane Encapsulation in Segment Routing-Enabled Juniper Network.

Complete Configuration Repository on GitHub:

https://github.com/bgphelp/blueprints/tree/master/evpn/vlan-based-mx
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Juniper High Availability Customer Site using AS-Prepend

Configuring Dual-CE BGP High Availability Site. This article provides Juniper Configuration Example that uses BGP AS-Prepend to identify primary and secondary paths.
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BGP Next-Hop Self Explained

One of the common questions asked by people who begin their BGP journey is related to BGP ‘Next-Hop Self’ configuration option. What does it do? Should I use it on my network? What will happen if I forget to configure it? Today we’ll try to answer these questions.
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BGP Looking Glass

Brief introduction into Public BGP Looking Glass servers and how to use them to troubleshoot real-life issues. 

One of the most common tasks performed by BGP administrator is troubleshooting of prefix propagation over the Internet. You might have originated a prefix advertisement from within your Autonomous System, but was this prefix accepted by your Upstream Peers? If it was, did your Transit peers propagate this information to the global Internet, or did the prefix get lost or summarized somewhere within their networks because you might set a wrong community? Is it possible that your prefix has been hijacked by somebody else?
Public Looks Glass (LG) and Router-Servers (RS) allow you to get an answer to these questions in a matter of seconds.
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Advertising Aggregates Routes

As a BGP admin, you will often need to make decisions on the ways to partition your IP Space, which routes to advertise to the Internet and which routes to suppress.

Ideally, you’d want to aggregate your IPv4/IPv6 Space as much as possible, by only advertising aggregate prefixes (also known as supernets and summary routes) to the Internet. Practically, this would mean that your Autonomous System (AS) will originate IP prefixes assigned to you by Regional Internet Registries (RIRs) or delegated to you by Upstream Providers, while suppressing all other advertisements. If everybody were to follow this rule, the Internet routing table would be much smaller and we would not have issues with FIB exhaustion.
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