Contents

EVPN overview·· 1

EVPN solutions· 1

EVPN VXLAN· 1

EVPN benefits· 1

MP-BGP extension for EVPN· 2

RD and route target selection of BGP EVPN routes· 2

EVPN overview

Ethernet Virtual Private Network (EVPN) is a Layer 2 VPN technology that provides both Layer 2 and Layer 3 connectivity between distant network sites. EVPN uses MP-BGP in the control plane and Virtual eXtensible LAN (VXLAN) or MPLS in the data plane. EVPN is typically used in data centers for multitenant services.

EVPN supports advertising private routes of VPN instances in an MPLS L3VPN network. For more information, see "Configuring EVPN L3VPN."

EVPN solutions

EVPN VXLAN

As shown in Figure 1, EVPN VXLAN uses the VXLAN technology for traffic forwarding in the data plane. The transport edge devices assign VMs to different VXLANs, and then forward traffic at Layer 2 between sites for VMs by using VXLAN tunnels. The transport edge devices are VXLAN tunnel endpoints (VTEPs). All EVPN VXLAN processing is performed on VTEPs

To provide Layer 3 connectivity between subnets of a tenant and between the EVPN VXLAN network and external networks, you can deploy EVPN gateways.

For more information about EVPN VXLAN, see "Configuring EVPN VXLAN."

Figure 1 EVPN VXLAN network model

EVPN benefits

EVPN provides the following benefits:

·     Configuration automation—MP-BGP automates VTEP discovery, VXLAN tunnel, and VXLAN tunnel assignment to ease deployment.

·     Separation of the control plane and the data plane—EVPN uses MP-BGP to advertise host reachability information in the control plane and uses VXLAN or MPLS to forward traffic in the data plane.

·     Integrated routing and bridging (IRB)—MP-BGP advertises both Layer 2 and Layer 3 host reachability information to provide optimal forwarding paths and minimize flooding in an EVPN VXLAN network.

MP-BGP extension for EVPN

To support EVPN, MP-BGP introduces the EVPN subsequent address family under the L2VPN address family and the following network layer reachability information (BGP EVPN routes):

·     Ethernet auto-discovery route—

·     MAC/IP advertisement route—Advertises MAC reachability information and host route information (host ARP or ND information).

·     Inclusive multicast Ethernet tag (IMET) route—Advertises VTEP and VXLAN mappings for automating VTEP discovery, VXLAN tunnel establishment, and VXLAN tunnel assignment in an EVPN VXLAN network.

·     Ethernet segment (ES) route—Advertises ES and VTEP mappings.

·     IP prefix advertisement route—Advertises BGP IPv4 or IPv6 unicast routes as IP prefixes.

MP-BGP uses the route distinguisher (RD) field to differentiate BGP EVPN routes of different VSIs or cross-connect groups and uses route targets to control the advertisement and acceptance of BGP EVPN routes.

MP-BGP supports the following types of route targets:

·     Export targets—A VTEP sets the export targets for BGP EVPN routes learned from the local site before advertising them to remote VTEPs.

·     Import targets—A VTEP checks the export targets of BGP EVPN routes received from remote VTEPs. The VTEP imports the BGP EVPN routes only when their export targets match the local import targets.

RD and route target selection of BGP EVPN routes

As shown in Table 1, you can configure RDs and route targets for BGP EVPN routes in multiple views.

Table 1 Supported views for RD and route target configuration

The device selects RDs and route targets for BGP EVPN routes by using the following rules:

·     Ethernet auto-discovery routes—The device uses the RD and route targets configured in EVPN instance view of a VSI or cross-connect group when advertising the routes. The device uses the route targets configured in EVPN instance view of a VSI or cross-connect group when accepting the routes.

·     IMET routes and MAC/IP advertisement routes that contain only MAC addresses—The device uses the RD and route targets configured in VSI EVPN instance view when advertising and accepting the routes.

·     MAC/IP advertisement routes that contain ARP or ND information—The device uses the following settings when advertising the routes:

¡     RD and export route targets configured in VSI EVPN instance view.

¡     Export route targets configured for EVPN on a VPN instance or the public instance (VPN instance view, EVPN view of a VPN instance or the public instance, and public instance view).

The device uses the import route targets configured for the EVPN instance on a VSI and EVPN on a VPN instance or the public instance when accepting the routes.

·     ES routes—The device uses the RD and export route targets configured for an EVPN instance on a VSI or cross-connect group when advertising the routes. The device uses the import route targets configured for an EVPN instance on a VSI or cross-connect group when accepting the routes.

·     IP prefix advertisement routes—The device uses the route targets configured for IPv4 or IPv6 VPN on a VPN instance or the public instance when advertising and accepting the routes.