Well first of all, let me clarify you, what is full
duplex mode and half duplex mode.
Full duplex means the interface can send and
receive data at the same time, everybody listens when everybody speaks, though
there no collision domain
Half duplex means you will have collisions and
slower network performance due to dropped packets, as systems back off and
resend their data, you speak I listen when everybody should be silence until my
conversation finish.
You need to assign a specific speed to switch
ports through following switch configuration commands or else interfaces are
being set to default speed as per the table below.
Interfaces always set to default speed as per
the table below.
Interface Type
|
Set speed capability(mbps)
|
Default
|
FastEthernet 10/100
ports
|
10/100/Auto
|
Auto
|
Gigabit Ethernet GBIC
ports
|
1000
|
1000
|
1000BASE-T
|
10/100/1000/Auto
|
Auto
|
You need to assign a specific speed to switch
ports through following switch configuration commands, wherever you see duplex
mismatch problem or user complain slow response, which means both ends have
different speed and duplex modes. Both ends must be configured same speed and
duplex modes.
Switch(config)# Interface gig 3/1
Switch(config)# speed auto
Switch(config)# duplex auto
Switch(config)# Interface gig 3/2
Switch(config)# speed 100
Switch(config)# duplex full
Remember-If
speed is set to auto, then the duplex can’t be manually set, duplex should also
be set auto
Verification
of interfaces speed and duplex settings
Before verifying port settings, you must see
the interface capability. If it is fast Ethernet 10/100 port, which is manually
set to speed 100, what do you do if other end gigabit Ethernet of default speed
1000mbps? So that verify the interfaces capabilities first and set speed
auto-auto, make sure both ends must be same speed.
To
verify the interface capabilities, use the below command
To verify the specific interface
speed and duplex setting, use the following commands.
And remember when the speed and
duplex setting are being set to default, you will see following symbolic
representation, as marked by red pen on below screen shots.
(1).They display auto-auto, when interface are
“not connected” other end.
(2).They display a-full and a-100 , when interfaces “connected”
to other end.
PC
end speed and duplex settings:
Click
"Start > Settings > Control Panel".
Select
"Network and Sharing Center".
On
the right panel select "Change Adapter settings"
Right
click on the "Local area Connection" and select
"Properties".
In
the "Local Area Connection Properties" window select the
"Configure" button.
Select
the "Advanced" tab.In the scroll list of options find "Speed
& Duplex" or "Link Speed & Duplex" and select it.
Auto Negotiation will be the default setting for win
7 computers.
