Configuring Unidirectional Ethernet

Note Unidirectional Ethernet is not supported on either Supervisor Engine 6-E or a Catalyst 4900M chassis.

This chapter describes how to configure Unidirectional Ethernet on the Catalyst 4000 family 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, first look at the Cisco Catalyst 4500 Series Switch Command Reference and related publications at this location:

http://www.cisco.com/en/US/products/hw/switches/ps4324/index.html

If the command is not found in the Catalyst 4500 Series Switch Command Reference, it will be found in the larger Cisco IOS library. Refer to the Catalyst 4500 Series Switch Cisco IOS Command Reference and related publications at this location:

http://www.cisco.com/en/US/products/ps6350/index.html

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)# unidirectional 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 neighbor 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