Unidirectional Ethernet uses only one strand of fiber for either transmitting or receiving one-way traffic, instead of two strands of fiber.

With unidirectional links either transmit or receive traffic for applications, such as video streaming, where most traffic sent is unacknowledged.You can create a unidirectional link by configuring ports equipped with bidirectional transceivers to unidirectionally transmit or receive traffic. You can use UDE when there is no appropriate unidirectional transceiver available. For example, without supported transmit-only transceivers, you must configure transmit-only links with software-based UDE.

• UDE send-only is supported.

• UDE receive-only is not supported till Cisco NX-OS Release 10.1(1).

• Beginning with Cisco NX-OS Release 10.1(2), UDE receive-only is also supported.

• Beginning with Cisco NX-OS Release 10.1(2), UDE is supported on N9K-X9624D-R2, N9K-X9636Q-R, N9K-X9636C-RX, N9K-X96136YC-R, N9K-X9624D-R2, N9K-X9636C-R, Cisco Nexus 3636C-R, and Cisco Nexus 36180YC-R modules.

• UDE can be enabled on all ports simultaneously.

• UDE on breakout is supported from Cisco NX-OS Release 10.1(1) and later releases.

• UDE at hardware level is supported only on Cisco Nexus 9500 switches with X97160YC-EX line cards.

• UDE is supported only for native 10G-LR/10G-LRS transceivers, and cannot be used with QSAs or breakout cables.

• Beginning with Cisco NX-OS Release 10.1(1), UDE is supported on the N9K-C9336C-FX2, N9KC93240YC-FX2, N9K-C93180YC-FX, N9K-C93360YC-FX2 TORs and N9K-X97160YC-EX line card.

• Beginning with Cisco NX-OS Release 10.1(1), UDE supports the following transceivers: 10G-SR, 10G-AOC, 40G-SR, 40G-LR, 40G-AOC, 100G-SR, 100G-LR, and 100G-AOC.

• Port flap may occur when you configure UDE on a port.

• You can add physical interfaces with and without UDE configuration into a port-channel. However, you must ensure only send-only interfaces are added to a port-channel. UDE may not work as expected if you mix send-only configuration with other interfaces.

• The port-channel may not receive packets if all members are configured as UDE send-only.

• The port-channel may not receive packets if all members are configured as UDE send-only which can prevent LCAP based port-channel to come up.

• Special control plane traffic pruning is not configured on send-only ports.

• Unidirectional ports do not support any features or protocols that require negotiation with the port at the other end of the link. You must disable all features that require bi-directional communication.