Catalyst 4500 Series Switch Cisco IOS Software Configuration Guide, 12.2(31)SGA
Configuring Unidirectional Ethernet
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Configuring Unidirectional Ethernet

Table Of Contents

Configuring Unidirectional Ethernet

Overview of Unidirectional Ethernet

Configuring Unidirectional Ethernet


Configuring Unidirectional Ethernet


This chapter describes how to configure Unidirectional Ethernet on the Catalyst 4500 series switch and contains these sections:

Overview of Unidirectional Ethernet

Configuring Unidirectional Ethernet


Note For complete syntax and usage information for the switch commands used in this chapter, refer to the Catalyst 4500 Series Switch Cisco IOS Command Reference and related publications at this location:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cr/index.htm.


Overview of Unidirectional Ethernet

You can set stubless Gigabit Ethernet ports to unidirectionally transmit or receive traffic. Unidirectional Ethernet uses only one strand of fiber for either transmitting or receiving one-way traffic for the GigaPort, instead of two strands of fiber for a full-duplex GigaPort Ethernet. Configuring your GigaPorts either to transmit or receive traffic effectively doubles the amount of traffic capabilities for applications, such as video streaming, where most traffic is sent as unacknowledged unidirectional video broadcast streams.

Configuring Unidirectional Ethernet


Note You must configure Unidirectional Ethernet on the non-blocking GigaPort, which will automatically disable UDLD on the port.


To enable Unidirectional Ethernet, perform this task:

 
Command
Purpose

Step 1 

Switch(config)# interface {vlan vlan_ID | 
{fastethernet | gigabitethernet | 
tengigabitethernet} slot/interface | Port-channel 
number} 

Selects the interface to configure.

Step 2 

Switch(config-if)# [no] unidirectional {send-only 
| receive-only} 

Enables Unidirectional Ethernet.

Use the no keyword to disable Unidirectional Ethernet.

Step 3 

Switch(config-if)# end 

Exits configuration mode.

Step 4 

Switch# show interface {vlan vlan_ID | 
{fastethernet | gigabitethernet | 
tengigabitethernet} slot/interface} 
unidirectional

Verifies the configuration.

This example shows how to set Gigabit Ethernet interface 1/1 to unidirectionally send traffic:

Switch# configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# interface gigabitethernet 1/1 
Switch(config-if)# unidirectional send-only
Switch(config-if)# end

Warning!

Enable l2 port unidirectional mode will automatically disable port udld. 
You must manually ensure that the unidirectional link does not create 
a spanning tree loop in the network.

Enable l3 port unidirectional mode will automatically disable ip routing
on the port. You must manually configure static ip route and arp entry
in order to route ip traffic.

This example shows how to set Gigabit Ethernet interface 1/1 to receive traffic unidirectionally:

Switch# configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# interface gigabitethernet 1/1 
Switch(config-if)# unidrectional receive-only
Switch(config-if)# end

Warning!

Enable l2 port unidirectional mode will automatically disable port udld. 
You must manually ensure that the unidirectional link does not create 
a spanning tree loop in the network.

Enable l3 port unidirectional mode will automatically disable ip routing
on the port. You must manually configure static ip route and arp entry
in order to route ip traffic.

This example shows how to verify the configuration

Switch>show interface gigabitethernet 1/1 unidirectional
  show interface gigabitethernet 1/1 unidirectional
  Unidirectional configuration mode: send only
  CDP neighbour unidirectional configuration mode: receive only

This example shows how to disable Unidirectional Ethernet on Gigabit Ethernet interface 1/1:

Switch# configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# interface gigabitethernet 1/1 
Switch(config-if)# no unidirectional
Switch(config-if)# end

This example shows the result of issuing the show interface command for a port that does not support Unidirectional Ethernet:

Switch#show interface f6/1 unidirectional
Unidirectional Ethernet is not supported on FastEthernet6/1