3
Working mechanisms
The VTEP uses the following process to forward an inter-site frame:
1. Discovers remote VTEPs, establishes VXLAN tunnels, and assigns the VXLAN tunnels to VXLANs.
2. Assigns the frame to its matching VXLAN if the frame is sent between sites.
3. Performs MAC learning on the VXLAN's VSI.
4. Forwards the frame.
This section describes this process in detail. For intra-site frames in a VSI, the system performs typical
Layer 2 forwarding and processes 802.1Q VLAN tags, as described in "Access modes of VSIs."
VXLAN tunnel establishment and assignment
To provide Layer 2 connectivity for a VXLAN between two sites, you must create a VXLAN tunnel between
the sites and assign the tunnel to the VXLAN.
VXLAN tunnel establishment
VXLAN supports manual and automatic VXLAN tunnel establishment.
• Manual creation—Manually create a VXLAN tunnel interface, and specify the tunnel source and
destination IP addresses on the peer VTEPs.
• Automatic creation—Configure the Enhanced Neighbor Discovery Protocol (ENDP) to
automatically discover VTEPs and set up VXLAN tunnels. For more information about ENDP, see
"Configuring ENDP."
VXLAN tunnel assignment
VXLAN supports manual and automatic VXLAN tunnel assignment.
• Manual assignment—Manually assign VXLAN tunnels to VXLANs.
• Automatic assignment—Run VXLAN IS-IS to advertise VXLAN IDs over all VXLAN tunnels between
VTEPs. Two VTEPs automatically assign the VXLAN tunnel between them to a VXLAN if both of them
have the VXLAN ID.
Assignment of traffic to VXLANs
Traffic from the local site to a remote site
The VTEP uses an Ethernet service instance to match a list of VLANs on a site-facing interface. The VTEP
assigns customer traffic from the VLANs to a VXLAN by mapping the Ethernet service instance to a VSI.
An Ethernet service instance is identical to an attachment circuit (AC) in L2VPN.
As shown in Figure 3, Ether
net service instance 1 matches VLAN 2 and is mapped to VSI A (VXLAN 10).
When a frame from VLAN 2 arrives, the VTEP assigns the frame to VXLAN 10, and looks up VSI A's
MAC address table for the outgoing interface.
