200-155 · Question #179
Which statement accurately describes NVGRE?
The correct answer is B. uses a virtual sublet ID to identify Layer 2 segment. Network Virtualization using Generic Routing Encapsulation (NVGRE) leverages a Virtual Subnet ID to uniquely identify Layer 2 network segments across an encapsulated tunnel.
Question
Which statement accurately describes NVGRE?
Options
- Acan be deployed in a unicast-only environment
- Buses a virtual sublet ID to identify Layer 2 segment
- Cuses a join interface to discover edge devices
- Duses a VTEP to originate and terminate tunnels
How the community answered
(29 responses)- A3% (1)
- B93% (27)
- D3% (1)
Why each option
Network Virtualization using Generic Routing Encapsulation (NVGRE) leverages a Virtual Subnet ID to uniquely identify Layer 2 network segments across an encapsulated tunnel.
NVGRE is designed to carry both unicast and BUM (broadcast, unknown unicast, multicast) traffic, often relying on IP multicast or head-end replication for BUM traffic, thus not suitable for a unicast-only environment.
NVGRE encapsulates Layer 2 Ethernet frames within GRE packets and uses a 24-bit Virtual Subnet ID (VSID) in the GRE header to differentiate and isolate virtual Layer 2 segments or tenant networks over a shared IP underlay network. This mechanism is crucial for multi-tenancy in virtualized environments.
NVGRE does not utilize a 'join interface' for discovering edge devices; discovery and tunnel endpoint management are handled by control plane mechanisms or static configuration.
VTEP (VXLAN Tunnel End Point) is a specific term associated with the VXLAN protocol for originating and terminating tunnels, not NVGRE.
Concept tested: NVGRE protocol features and VSID
Source: https://learn.microsoft.com/en-us/windows-server/networking/sdn/technologies/nvgre/nvgre
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