NVGRE (Network Virtualization using Generic Routing Encapsulation) is a tunneling protocol designed to enable network virtualization in data center environments. It provides a solution for creating virtual networks on top of existing IP networks, allowing multiple virtual networks to coexist and be isolated from each other. Let’s explore the concept and workings of NVGRE, including versions and working examples:
- Concept of NVGRE:
- NVGRE is a tunneling protocol that extends Layer 2 connectivity across IP networks, enabling network virtualization.
- It is primarily used in multi-tenant environments, such as data centers, where virtual networks need to be created and isolated.
- NVGRE encapsulates Layer 2 Ethernet frames within IP packets, allowing virtual machines (VMs) in different subnets or VLANs to communicate with each other over an IP infrastructure.
- NVGRE Versions:
- NVGRE is a standardized protocol defined by the Network Virtualization Overlays (NVO3) working group in the IETF (Internet Engineering Task Force).
- There is no specific version associated with NVGRE; it is considered a single protocol.
- NVGRE Working Example:
- Let’s consider a scenario where multiple virtual networks (VN1, VN2, VN3) need to be created within a data center infrastructure using NVGRE.Each virtual network has its own virtual subnet and VLAN IDs.The NVGRE tunnel endpoints (NVGRE gateways) are deployed at the edge of the data center network to encapsulate and decapsulate NVGRE packets.When a VM in VN1 wants to communicate with a VM in VN2, the Ethernet frame from the source VM is encapsulated in an NVGRE packet and sent to the destination NVGRE gateway.The destination NVGRE gateway decapsulates the NVGRE packet, retrieves the original Ethernet frame, and forwards it to the destination VM within VN2.
- Example NVGRE Configuration (NVGRE Gateway at Data Center Edge)
interface Tunnel0 ip address 192.0.2.1 255.255.255.0 tunnel source 203.0.113.1 tunnel destination 198.51.100.1
In the example above, an NVGRE tunnel is established between the NVGRE gateways at the data center edge. The tunnel interface is configured with an IP address, source, and destination addresses. Ethernet frames from VMs within virtual networks are encapsulated within NVGRE packets and transmitted over the IP network to the destination NVGRE gateway, where they are decapsulated and forwarded to the appropriate virtual network.
NVGRE enables network virtualization and isolation in multi-tenant environments, providing flexibility and scalability for data centers. It allows multiple virtual networks to coexist on the same physical infrastructure while maintaining logical separation and security between them.
