Vyatta NOS documentation

Learn how to install, configure, and operate Vyatta Network Operating System (Vyatta NOS), which helps to drive our virtual networking and physical platforms portfolio.

VXLAN compared to VXLAN-GPE

A standard VXLAN frame encapsulates Ethernet frames in an outer UDP/IP transport. The payload within a VXLAN packet is required to be a full Ethernet frame.

VXLAN-GPE frame adds a GPE header to extend the existing VXLAN protocol to provide support for multiprotocol encapsulation, operations, administration and management (OAM) signaling and explicit versioning. VXLAN-GPE is a backwards-compatible extension to VXLAN to allow overlay traffic of several types (including but not limited to Ethernet) to be transported over the underlying IP network.

Comparison of a Standard VXLAN Header with a GPE VXLAN Header

Standard VXLAN header:

0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|R|R|I|R|R|R|            Reserved                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                VXLAN Network Identifier (VNI) |   Reserved    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

VXLAN GPE header:

0                    1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|Ver|I|P|B|O|       Reserved                |Next Protocol  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                VXLAN Network Identifier (VNI) |   Reserved    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Fragmentation Considerations for VXLAN GPE
VTEPs must never fragment an encapsulated VXLAN GPE packet, and when the outer IP header is IPv4, VTEPs must set the DF bit in the outer IPv4 header. The underlay network should be configured to carry an MTU large enough to accommodate the added encapsulation headers. It is recommended that VTEPs perform Path MTU discovery to determine if the underlay network can carry the encapsulated payload packet.
Connecting a VXLAN VTEP to a VXLAN GPE VTEP
To connect a VXLAN VTEP to a VXLAN GPE VTEP, use the following guidelines.
  • A VXLAN VTEP conforms to VXLAN frame format and uses UDP destination port 4789 when sending traffic to a VXLAN GPE VTEP.
  • As per VXLAN, reserved bits 5 and 7, VXLAN GPE P and O-bits respectively must be set to zero.
  • The remaining reserved bits must be zero, including the VXLAN GPE version field, bits 2 and 3.
  • The encapsulated payload must be Ethernet.
Connecting a VXLAN GPE VTEP to a VXLAN VTEP
To connect a VXLAN-GPE VTEP to a VXLAN-VTEP, use the following guidelines.
  • Do not encapsulate non-Ethernet frames to a VXLAN VTEP.
  • Conform to VXLAN frame format: set the P bit to 0, the Next Protocol to 0 and use UDP destination port 4789.
  • A VXLAN GPE VTEP MUST also set O = 0 and Ver = 0 when encapsulating Ethernet frames to VXLAN VTEP.
  • The receiving VXLAN VTEP will treat the packet as a VXLAN packet.
Note: With VXLAN GPE, issues such as spoofing, flooding, and traffic redirection are dependent on the particular protocol payload encapsulated.