H3C S10500 Series Configuration Manual page 15

A distributed EVPN gateway uses symmetric IBR for Layer 3 forwarding, which means both the
ingress and egress gateways perform Layer 2 and Layer 3 lookups. Symmetric IBR introduces the
following concepts:
•
L3 VXLAN ID—Also called L3 VNI. An L3 VXLAN ID identifies the traffic of a routing domain
where devices have Layer 3 reachability. An L3 VXLAN ID is associated with one VPN instance.
Distributed EVPN gateways use VPN instances to isolate traffic of different services on VXLAN
tunnel interfaces.
•
Router MAC address—Each distributed EVPN gateway has a unique router MAC address
used for inter-gateway forwarding. The MAC addresses in the inner Ethernet header of VXLAN
packets are router MAC addresses of distributed EVPN gateways.
As shown in
•
VSI interface as a gateway interface of a VXLAN—The VSI interface acts as the gateway
interface for VMs in a VXLAN. The VSI interface is associated with a VSI and a VPN instance.
On different distributed EVPN gateways, the VSI interface of a VXLAN use the same IP address
to provide services.
•
VSI interface associated with an L3 VXLAN ID—The VSI interface is associated with a VPN
instance and assigned an L3 VXLAN ID. VSI interfaces associated with the same VPN instance
share an L3 VXLAN ID.
A border gateway only has VSI interfaces that are associated with an L3 VXLAN ID.
Figure 9 Example of distributed EVPN gateway deployment
Layer 3 forwarding entry learning
A distributed EVPN gateway forwards Layer 3 traffic based on FIB entries generated from EVPN
routes and ARP information.
A VTEP advertises an external route imported in the EVPN address family through MP-BGP. A
remote VTEP adds the route to the FIB table of a VPN instance based on the L3 VXLAN ID carried in
Figure 9, each distributed EVPN gateway has the following types of VSI interfaces:
8