H3C Technologies H3C S6800 Series Switches - Manual (Page 13)

5
Unicast
The following process (see Figure 4 ) applies to a known unicast frame between sites:
1. The source VTEP encapsulates the Ethernet frame in the VXLAN/UDP/IP header.
In the outer IP header, the source IP address is the source VTEP's VXLAN tunnel source IP address.
The destination IP address is the VXLAN tunnel destination IP address.
2. The source VTEP forwards the encapsulated packet out of the outgoing VXLAN tunnel interface
found in the VSI's MAC address table.
3. The intermediate transport devices (P devices) forward the frame to the destination VTEP by using
the outer IP header.
4. The destination VTEP removes the headers on top of the inner Ethernet frame. It then performs MAC
address table lookup in the VXLAN's VSI to forward the frame out of the matching outgoing
interface.
Figure 4 Inter-site unicast
Flood
The VTEP floods a broadcast, multicast, or unknown unicast frame to all site-facing interfaces and VXLAN
tunnels in the VXLAN, except for the incoming interface.
VXLAN supports the following modes for flood traffic:
• Unicast mode—Also called head-end replication. The source VTEP replicates the flood frame, and
then sends one replica to the destination IP address of each VXLAN tunnel in the VXLAN. See
Figure
5 .
• Multicast mode—Also called tandem replication. The source VTEP sends the flood frame in a
multicast VXLAN packet destined for a multicast group address. Transport network devices replicate
and forward the packet to remote VTEPs based on their multicast forwarding entries. See Figure 6 .
• Flood proxy mode—The source VTEP sends the flood frame in a VXLAN packet over a VXLAN
tunnel to a flood proxy server. The flood proxy server replicates and forwards the packet to each
remote VTEP through its VXLAN tunnels. See
Figure 7 .
VTEP 1 VTEP 2
Transport network
P
Server 1
VM 1
VM 2
VM 3
Server 3
VM 7
VM 8
VM 9
MAC Table on VTEP 1
VXLAN/VSI MAC Interface
VXLAN 10/VSI A MAC 1 FGE1/0/1, VLAN 2
VXLAN 10/VSI A MAC 7 Tunnel 1
Server 2
VM 4
VM 5
VM 6
FGE1/0/1
FGE1/0/2
MAC Table on VTEP 2
VXLAN/VSI MAC Interface
VXLAN 10/VSI A MAC 1 Tunnel 1
VXLAN 10/VSI A MAC 7 FGE1/0/1, VLAN 20
FGE1/0/1
VXLAN tunnel 1