The most basic technology of network virtualization is layering (overlay and underlay). There are two ways to achieve layering: one is mapping and the other is encapsulation ).
The main idea of ing is to replace the message semantics during forwarding, and how to replace it will require the device to query.
Encapsulation is to add the required message semantics to the network package. during processing, the packets can be parsed and encapsulated layer by layer, and the device should be as transparent as possible.
Many protocols provide encapsulated partial or complete functions, including IP-in-IP, VLAN, MPLS, vxlan, nvgre, and STT. These protocols have their own characteristics. Many of them are designed to isolate or connect different networks through tunnels. In particular, the design concepts are similar, but the implementation details are different.
The demand for general encapsulation protocol standards has become increasingly strong, so there is a need for Geneve: Generic network virtualization alization encapsulation.
The starting point of Geneve is to solve the problem of metadata information added during encapsulation (How many bits should be used) and try to adapt to various virtualization scenarios, the underlay protocol is the most common IP protocol (UDP ).
Similar to most encapsulation protocols, implementing Geneve generally requires two types of devices: Tunnel endpoints and transit devices ). The former is used to process the Encapsulation Header to terminate the tunnel, while the latter is not required. It is usually a device that supports IP forwarding.
For details, the encapsulated frames of Geneve are
Outer Ethernet header
Outer IP header (V4 or V6)
Outer UDP Header
Geneve header (variable length)
Inner Ethernet header
Payload
Outer ethereum Header
The UDP destination port is 6081 allocated by IANA by default and can be configured. The UDP checksum must be calculated correctly or set to 0.
Geneve supports unicast, multicast, and broadcast.
Geneve of basic network virtualization Protocol
