Configure Ethernet Ports with Auto-Negotiation

Configure Ethernet ports so they operate optimally for your network conditions.

About this task

When you use 1 Gigabit Ethernet SFP transceivers, the software disables Auto-Negotiation on the port. If you use 1 Gbps SFP transceivers, the remote end must also have Auto-Negotiation disabled.

All ports that belong to the same MLT or Link Aggregation Control Protocol (LACP) group must use the same port speed. In the case of MLTs, the software does not enforce this.

The software requires the same Auto-Negotiation settings on link partners to avoid incorrect declaration of link status. Mismatched settings can cause the links to stay down. Ensure the Auto-Negotiation settings between local ports and their remote link partners match before you upgrade the software.

Procedure

Enter GigabitEthernet Interface Configuration mode:

enable

configure terminal

interface GigabitEthernet {slot/port[/sub-port][-slot/port[/sub-port]][,...]}

Note

If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port.
Enable Auto-Negotiation:

auto-negotiate [port {slot/port[/sub-port][-slot/port[/sub-port]][,...]}] enable
Verify the configuration:

show interfaces gigabitEthernet l1-config [{slot/port[/sub-port][-slot/port[/sub-port]][,...]}]

Example

Switch:>enable
Switch:1#configure terminal
Switch:1(config)#interface gigabitethernet 1/8
Switch:1(config-if)#auto-negotiate enable
Switch:1(config-if)#show interfaces gigabitEthernet l1-config 1/8
==================================================================================================
                                          Port Config L1
==================================================================================================
PORT     AUTO  OPERATE  CUSTOM AUTO NEGOTIATION    ADMIN       OPERATE     ADMIN         OPERATE
NUM      NEG.  AUTO-NEG ADVERTISEMENTS             DPLX SPD    DPLX SPD    TX-FLW-CTRL   TX-FLW-CTRL
--------------------------------------------------------------------------------------------------
1/8      true  true     Not Configured             full 10000  0           enable       enable

Variable Definitions

The following table defines parameters for the auto-negotiate command.


Variable	Value
`{slot/port[/sub-port] [-slot/port[/sub-port]] [,...]}`	Specifies the port or ports that you want to configure.
enable	Enables auto-negotiation for the port or other ports of the module. The default Auto-Negotation behavior depends on the switch model and transceiver type.