ECN: VXLAN tunnels

Devices support explicit congestion notification (ECN) for packets that are encapsulated across VXLAN tunnels, as follows:

• During VXLAN encapsulation at the source virtual tunnel endpoint (VTEP), the switch copies the ECN bits from the original packet IP header to the outer VXLAN encapsulation IP header.
• During de-encapsulation at the remote VTEP, the switch copies the ECN bits from the outer VXLAN encapsulation IP header to the original packet IP header.

You can configure the vxlan-disable-copy-tos-encap statement or the vxlan-disable-copy-tos-decap statement at the [edit forwarding-options] hierarchy on the encapsulation or de-encapsulation ends of the tunnel, respectively, to disable the ECN copy operation.

Note: By default, some devices that support VXLAN tunnels also copy the DSCP bits of the Type of Service (ToS) field in the IP header to the VXLAN header upon encapsulation, and the same from the VXLAN header to the IP header upon de-encapsulation. The vxlan-disable-copy-tos-encap statement and the vxlan-disable-copy-tos-decap statement disable copying both the DSCP and ECN bits in the ToS field.