VXLAN (Virtual eXtensible Local Area Network, virtual extended local area network), is NVO3 (Network Virtualization) defined by IETF over Layer 3) One of the standard technologies, using L2 over L4 (MAC-in-UDP) packet encapsulation mode, which encapsulates Layer 2 packetsEncapsulation with the Layer 3 protocol can realize the expansion of the Layer 2 network within the scope of the Layer 3, and at the same time meet the needs of the large Layer 2 virtual migration and multi-tenancy of the data center.

VTEP (VXLAN Tunnel Endpoints, VXLAN tunnel endpoints): VXLAThe edge device of the N network is the start and end point of the VXLAN tunnel, and the related processing of VXLAN packets is performed on this.

VNI (VXLAN Network Identifier, VXLAN network identifier):

VXLAThe N header and the original Ethernet frame are used as UDP data. In the UDP header, the destination port number (VXLAN Port) is fixed to 4789, the source port number (UDP Src. Port) is the value of the original ether frame calculated by the hash algorithm.

source IP address (Outr Src. IP) is the V to which the source VM belongsThe IP address of the TEP, the destination IP address (Outer Dst. IP) is the V to which the destination VM belongsIP address of the TEP.

Source MAC address (Src. MAC Addr.) is the MAC address of the VTEP to which the source VM belongs, and the destination MAC address (Dst. MAC Addr.) is the MAC address of the next-hop device on the path to the destination VTEP.

To support EVPN, BGP EVPFive new EVPNs have been added to the N address family NLRI (Network Layer Reachability Information, network layer reachability information), that is, EVPN routing:

Ethernet Auto-discovery Route (RT-1): used to advertise ES information in site multi-homing networking to achieve split horizon and Aliasingand active/standby backup.

MAC/IP Advertisement Route (RT-2): used to advertise MAC/IP address information.

Inclusive Multicast Ethernett Tag Route (RT-3): It is used to advertise VTEP and its VXLAN to realize automatic VTEP discovery, automatic establishment of VXLAN tunnel, automatic creation of VXLAN broadcast table, etc.

Ethernet Segment Route (RT-4): used to advertise ES and its connected VTEP information, so as to discover other members of the VTEP redundancy group connected to the same ES, and to elect a designated forwarder DF among the redundancy groups.

IP Prefix Advertisement Route (RT-5): IP prefix route, used to advertise imported external routes in the form of IP prefixes.

BFDThe one-arm echo function detects the connectivity of the forwarding link through the loopback operation of BFD packets.

Among two directly connected devices, one device supports the BFD function, and the other device does not support the BFD function and only supports basic network layer forwarding. To quickly detect the fault between the two devices, you can create a BFD session with the one-arm echo function on the device that supports the BFD function. A device that supports the BFD function actively initiates the echo request function, and a device that does not support the BFD function directly loops back the packet after receiving it, thereby implementing the connectivity detection function of the forwarding link.

One-arm detection Huawei equipment will send one to the opposite end every 3S or soUDP packet, the source IP and destination IP in the packet are the IP of their own interface

VRRP forIPv4 supports VRRPv2 and VRRPv3, while VRRP for IPv6 only supports VRRPv3. Through packet construction, it can be found that v2 has an authentication field, but v3 does not.