About ethernet autonegotiation.

[speculor_cisco]

Suppose I enter these commands:

Switch(config)#int fa1/1

Switch(config-if)#speed 100

Switch(config-if)#duplex auto

It is not clear if with this configuration the interface can do autonegotiation.

And if the interface can do autonegotiation, it is not clear if the autonegotiation is only for duplex setting

or also for speed setting.

Thanks.

[speculor_cisco]

Ok.

But what about the other default:

10/100: Speed 10/100, Duplex Full

Do you know any standard that says that the default for 10/100 is full duplex?

If so, is this standard IEEE 802.3?

[Ajay Patel]

Hi Speculor,

I am not sure about any standard which talk about Interface specification; I tried to find someone Document which can clear on this point, but couldn't find.

Whatever I am taking about based on my Experience since I have worked with different Vendor (Nortel & Juniper) which follow the same.

if you get any input from other resource Please share with me so I also will know more into.

Thank you

Ajay

[CHRISTOPHER LARSON]

"There is No proper document which talk about Speed and Duplex exect configuration"

There is for Cisco devices and gigabit Ethernet. It is a best practices document and here is what it says:

The configuration of autonegotiation is much more critical in a GE environment than in a 10/100 Mbps environment. Only disable autonegotiation in these situations:

*  On switch ports that attach to devices that are not able to support negotiation
* Where connectivity issues arise from interoperability issue

So for gigabit links, there is a proper document that discusses it.  It says that it should be auto negotiate. So it is not the exact configuration, but it is precise in its intent and all that is needed is for a person to determine how exactly how to set and verify auto for their platform.