EVPN Overview for Switches

An Ethernet VPN (EVPN) enables you to connect a group of dispersed customer sites using a Layer 2 virtual bridge. As with other types of VPNs, an EVPN comprises customer edge (CE) devices (host, router, or switch) connected to provider edge (PE) devices. The PE devices can include an MPLS edge switch (MES) that acts at the edge of the MPLS infrastructure. For the initial deployment of EVPNs using Juniper Networks equipment, you can configure an EX9200 switch to act as an MES. You can deploy multiple EVPNs within the network, each providing network connectivity to customers while ensuring that traffic sharing that network remains private.

The MESs are interconnected within the network by using label-switched paths (LSPs). The MPLS infrastructure allows you to take advantage of the MPLS functionality provided by the Junos operating system (Junos OS), including fast reroute, node and link protection, and standby secondary paths. For EVPNs, learning between MESs takes place in the control plane rather than in the data plane (as is the case with traditional network bridging). The control plane provides greater control over the learning process, allowing you to restrict which devices discover information about the network. You can also apply policies on the MESs, allowing you to carefully control how network information is distributed and processed. EVPNs utilize the BGP control plane infrastructure, providing greater scale and the ability to isolate groups of devices (hosts, servers, virtual machines, and so on) from each other.

The MESs attach an MPLS label to each MAC address learned from the CE devices. This label and MAC address combination is advertised to the other MESs in the control plane. Control plane learning enables load balancing and improves convergence times in the event of certain types of network failures. The learning process between the MESs and the CE devices is completed using the method best suited to each CE device (data plane learning, IEEE 802.1, LLDP, 802.1aq, and so on).

The policy attributes of an EVPN are similar to an IP VPN (for example, Layer 3 VPNs). Each EVPN routing instance requires that you configure a route distinguisher and one or more route targets. A CE device attaches to an EVPN routing instance on an MES through an Ethernet interface that might be configured for one or more VLANs.

The following features are available for EVPNs:

• Ethernet connectivity between data centers spanning metropolitan area networks (MANs) and WANs

• One or more VLANs for each MAC VPN

• Automatic route distinguishers

• Dual-homed EVPN connection with active standby multihoming

• Starting with Junos OS Releases 16.1R4 and 16.2R2, the active-active mode for EVPN multihoming is supported.

• Starting with Junos OS Release 17.3R1, both pure type-5 routes and standard type-5 routes are supported on EX9200 switches. Use this feature, which advertises IP prefixes through EVPN, when the Layer 2 domain does not exist at the remote data centers or metro network peering points. For more information about how to configure, see ip-prefix-routes.

• Starting with Junos OS OS Release 17.3R1, VXLAN encapsulation is supported. Previously, only MPLS encapsulation is supported.

• Starting in Junos OS Evolved Release 22.4R1, you can configure nonstop active routing (NSR).

  Support doesn't include Graceful restart (GRES) or VLAN-aware service.

The following features are not supported for EVPNs:

• Graceful restart and graceful Routing Engine switchover (GRES).