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Auto-Negotiation on Ethernet Interfaces
Setting speed and duplex mode of Ethernet Interfaces
By default, auto-negotiation of speed and duplex mode is enabled on 10/100/1000 Base-T Ethernet
interfaces. Only 10GE interfaces do not support auto-negotiation. When using 10GE interfaces, verify that
the settings on the connecting devices are set to no auto-negotiation.
The local interface and the directly connected remote interface must have the same setting, and
auto-negotiation is the easiest way to accomplish that, as long as the remote interface is capable of
auto-negotiation.
Note: As a best practice, Dell Force10 recommends keeping auto-negotiation enabled. Auto-negotiation
should only be disabled on switch ports that attach to devices not capable of supporting negotiation or
where connectivity issues arise from interoperability issues.
For 10/100/1000 Ethernet interfaces, the
negotiation auto command is tied to the speed command.
Auto-negotiation is always enabled when the
speed command is set to 1000 or auto.
To discover whether the remote and local interface require manual speed synchronization, and to manually
synchronize them if necessary, use the following command sequence (see Figure 20-35 on page 456):
Note: Starting with FTOS 7.8.1.0, when a copper SFP2 module with catalog number GP-SFP2-1T is used
in the S25P model of the S-Series, its speed can be manually set with the speed command. When the
speed is set to 10 or 100 Mbps, the duplex command can also be executed.
Step Task Command Syntax Command Mode
1 Determine the local interface status. See
Figure 20-34.
show interfaces [interface | linecard
slot-number] status
EXEC Privilege
2 Determine the remote interface status. [Use the command on the remote system
that is equivalent to the above command.]
EXEC
EXEC Privilege
3 Access CONFIGURATION mode.
config
EXEC Privilege
4 Access the port. interface interface slot/port CONFIGURATION
5 Set the local port speed. speed {10 | 100 | 1000 | auto} INTERFACE
6 Optionally, set full- or half-duplex. duplex {half | full} INTERFACE
7 Disable auto-negotiation on the port. If the
speed was set to 1000, auto-negotiation
does not need to be disabled.
no negotiation auto
INTERFACE
8 Verify configuration changes.
show config
INTERFACE