VXLAN Forwaring

[tawa-ndafa]

I have a question, is the VXLAN packet packet labelled correctly? Which part is underlay and overlay below?.

[M02@rt37]

Hello @tawa-ndafa,

VxLAN act as the Overlay Data Plane. Then where you see VxLAN Network Identifier "VNI" this is the Overlay part.

V1 V2 and V3 stand for VTEP.

VTEP sources encapsulate the original data frames sent by the source server into VXLAN packets, which are then sent to the destination VTEP over an IP network. VXLAN packets are then decapsulated by the destination VTEP into the original data frames and forwarded to the destination server. Through its IP interface, a VTEP device also discovers the remote VTEPs for its VXLAN segments and learns the mappings from remote MAC addresses to VTEPs. VTEPs are functional units that create L2 connectivity over transport IP networks based on logical topologies.

Packets are routed based on the outer IP address header, which has the initiating VTEP's address as the source address and the terminating VTEP's address as the destination address.

[tawa-ndafa]

"VxLAN act as the Overlay Data Plane. Then where you see VxLAN Network Identifier "VNI" this is the Overlay part." the UDP and SMAC/DMAC/SIP/DIP are VTEP PIPs. Why are they marked as Underlay? I thought that's the overlay and payload encapsulated inside is the underlay?.

[M02@rt37 · Accepted solution]

@tawa-ndafa,

The UDP header and source/destination MAC/IP addresses you mentioned are indeed used for communication between VTEPs, which are responsible for encapsulating and decapsulating the overlay traffic. The terms "overlay" and "underlay" refer to different network layers. The overlay includes the encapsulated traffic (VXLAN frames), while the underlay comprises the physical network infrastructure that carries these encapsulated frames. The UDP and MAC/IP addresses in the VTEP headers are part of the underlay infrastructure, helping route the encapsulated traffic between VTEPs.