Interface Commands

4-157

4
Default Setting
Auto-negotiation is enabled by default.
When auto-negotiation is disabled, the default speed-duplex setting is 100half
for 100BASE-TX ports and 1000full for Gigabit Ethernet ports.
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
The 1000BASE-T standard does not support forced mode. Auto-negotiation
should always be used to establish a connection over any 1000BASE-T port
or trunk. If not used, the success of the link process cannot be guaranteed
when connecting to other types of switches.
To force operation to the speed and duplex mode specified in a speed-duplex
command, use the no negotiation command to disable auto-negotiation on
the selected interface.
When using the negotiation command to enable auto-negotiation, the
optimal settings will be determined by the capabilities command. To set the
speed/duplex mode under auto-negotiation, the required mode must be
specified in the capabilities list for an interface.
Example
The following example configures port 5 to 100 Mbps, half-duplex operation.
Related Commands
negotiation (4-157)
capabilities (4-158)

negotiation

This command enables autonegotiation for a given interface. Use the no form to
disable autonegotiation.
Syntax
[no] negotiation
Default Setting
Enabled
Command Mode
Interface Configuration (Ethernet, Port Channel)
Console(config)#interface ethernet 1/5
Console(config-if)#speed-duplex 100half
Console(config-if)#no negotiation
Console(config-if)#