NVGRE - Network Virtualization using GRE

What is NVGRE?

NVGRE (Network Virtualization using Generic Routing Encapsulation) is a network virtualization protocol that encapsulates Layer 2 Ethernet frames within GRE (Generic Routing Encapsulation) tunnels over an IP network.

Why is NVGRE useful?

NVGRE enables scalable multi-tenant networks by allowing multiple isolated virtual networks to coexist over a shared physical infrastructure. It overcomes VLAN scalability limits and supports cloud computing environments.

How it works?

NVGRE wraps Layer 2 Ethernet frames with a GRE header and transports them over an IP network. Each virtual network is identified using a 24-bit Tenant Network Identifier (TNI), enabling traffic isolation and scalability.

Where is NVGRE used?

NVGRE is mainly used in data centers and enterprise cloud infrastructures for virtual network overlays, especially in Microsoft-based environments like Hyper-V and Windows Server.

Which OSI layer does this protocol belong to?

NVGRE primarily operates at Layer 2 (Data Link Layer) for encapsulation, but is transported across Layer 3 (Network Layer) using GRE.

Is NVGRE Windows specific?

NVGRE is heavily supported in Microsoft environments (e.g., Hyper-V, System Center), but it is not exclusive to Windows. However, adoption outside Windows is limited.

Is NVGRE Linux specific?

No, NVGRE is not Linux specific, but Linux can support it through GRE tunneling and software-defined networking tools, although it is less common than VXLAN in Linux-based systems.

Which Transport Protocol is used by NVGRE?

NVGRE uses GRE (Generic Routing Encapsulation) as the transport protocol, which is an IP protocol (not TCP/UDP-based).

Which Port is used by NVGRE?

NVGRE does not use a specific port number. It uses IP protocol number 47 for GRE encapsulation.

Is NVGRE using Client server model?

No, NVGRE does not use a client-server model. It is a tunneling protocol used for encapsulating and transporting network traffic across virtualized environments.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

  • rfc details

  • setup

  • setup

  • packet details

  • usecases

  • features

  • Reference links