Configuring Unidirectional Ethernet

This chapter describes how to configure Unidirectional Ethernet on the Cisco Nexus 9000 series switches.

Unidirectional Ethernet

Unidirectional Ethernet (UDE) is a network technology that lets you communicate using a single fiber strand for transmitting or receiving data.

With unidirectional links, you can transmit or receive traffic video streaming applications. In these scenarios, most traffic is sent as one-way streams that are not acknowledged.

To create a unidirectional link, configure the port with a bidirectional transceiver so it transmits or receives traffic in one direction.

Use UDE when an appropriate unidirectional transceiver is not available. If transmit-only transceivers are unavailable, configure transmit-only links with software-based UDE.

Best practices for Unidirectional Ethernet configuration

Use these best practices and recommendations to configure UDE on your Nexus switches

  • Configure UDE in send-only mode on your Nexus switches. You cannot use UDE receive-only in releases before Cisco NX-OS Release 10.1(2).

  • You can enable UDE on all ports at the same time.

  • You can use breakout support for UDE starting with Cisco NX-OS Release 10.1(1) and later.

  • Port flapping may occur when you configure UDE on a port. You can add physical interfaces with and without UDE configuration into a port-channel. Only add send-only interfaces are added to a port channel.

    If you mix send-only configuration with other interfaces, UDE might not work.

  • If you configure all members of the port channel as UDE send-only, the port channel may not receive packets.

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

  • Unidirectional ports do not support features or protocols that require negotiation with the remote port. Disable all features that require bi-directional communication.

UDE support on Nexus switches

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

  • Beginning with Cisco NX-OS Release 10.1(2), UDE is supported on these Cisco Nexus switches:

    • N9K-X9624D-R2

    • N9K-X9636Q-R

    • N9K-X9636C-RX

    • N9K-X96136YC-R

    • N9K-X9624D-R2

    • N9K-X9636C-R

  • You can use UDE at the hardware level only on Cisco Nexus 9500 switches with X97160YC-EX line cards

  • Beginning with Cisco NX-OS Release 10.1(1), UDE is supported on these switches:

    • Cisco Nexus 9000 EX, FX, FX2 and FX3 platform switches

    • N9K-C9336C-FX2

    • N9KC93240YC-FX2

    • N9K-C93180YC-FX

    • N9K-C93360YC-FX2 TOR switches

    • 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.

Configure Unidirectional Ethernet

Configure the ethernet interface for unidirectional communication on the switch. Set the interface to send-only or receive-only mode.

Procedure

  Command or Action Purpose

Step 1

Enter interface configuration mode using the interface ethernet {type slot /port} command.

Example:

switch(config)# interface ethernet 3/1

Step 2

Configure send-only mode using the unidirectional send-only command.

Example:

switch(config-if)# unidirectional send-only

Step 3

Configure receive-only mode using the unidirectional receive-only command.

Example:

switch(config-if)# unidirectional receive-only

Step 4

Exit interface mode using the exit command.

Example:

switch(config)# exit

Step 5

Display the running configuration for the interface using the show running-config interface {type slot /port} command.

Example:

switch(config)# show running-config interface ethernet 3/1

Step 6

Save the configuration using the copy running-config startup-config command.

Example:

switch(config)# copy running-config startup-config

You have configured the Ethernet interface for unidirectional operation.

Example

This example shows how to configure an Ethernet interface for send-only unidirectional communication.

switch# configure terminal
switch(config)# interface ethernet 3/1
switch(config-if)# unidirectional send-only
switch(config-if)# exit
switch(config)# exit
switch#

This example shows how to display the running configuration for the interface to verify the unidirectional setting and save the configuration. 

switch# show running-config interface ethernet 3/1
!
interface ethernet 3/1
  unidirectional send-only
!