Juniper PHYSICAL LAYER - CONFIGURATION GUIDE V11.1.X Configuration Manual page 223

duplex
NOTE: If you set either the line speed or duplex mode to automatically negotiate by
using the automatically negotiate keyword, the router negotiates both parameters.
You can specify different values to prevent the router from negotiating these
parameters.
Automatic negotiation is not supported for the FE-8 SFP I/O module. For this I/O
module, full duplex mode is the default.
ethernet description
interface fastEthernet
Use the no version to restore the default value, 1 second.
See debounce-interval.
Use to specify the duplex mode.
This command also works on the Fast Ethernet port on the SRP module on all
E Series routers. For more information, see JUNOSe System Basics Configuration
Guide.
Example
host1(config-if)#duplex full
Use the no version to revert to the default, either automatically negotiate or full
duplex (FE-8 SFP I/O module only)
See duplex.
Use to associate a text description of up to 64 characters with an Ethernet
interface.
This command does not work for the Fast Ethernet port on the SRP module.
The description is displayed in the output for show configuration, show
interfaces fastEthernet, show interfaces gigabitEthernet, and show interfaces
tenGigabitEthernet commands.
Example
host1(config-if)#ethernet description abcd1234
Use the no version to remove the description from the interface.
See ethernet description.
Use to select a Fast Ethernet interface on a line module.
You can also use it to select a Fast Ethernet management port on an SRP I/O
module (ERX7xx models, ERX14xx models, and the ERX310 router) or an SRP
IOA (E120 and E320 routers). For information about managing the Fast Ethernet
port on the SRP module, see JUNOSe System Basics Configuration Guide.
Chapter 5: Configuring Ethernet Interfaces
Configuring the Physical Interface
201