[X460G2] speed and duplex settings and behaviour on 1GbE port.

[raphaelp]

Hi,

On X460G2 model (with EXOS 22.4.1.4 or EXOS 30.6.1.11) we noticed a misunderstood behaviour with "intel" comptuers connected on Etremexe ports configured in auto-sense mode with speed and duplex settings ( instead off "auto on" only).

For instance, if on Extreme side we configure the port 3 like :" configure ports 3 auto on speed 1000 duplex full on"

And we configure  a computer with its network interface configured in auto-sense mode.

After, we are waiting 1 minute and then we connect the computer on port 3 ; we noticed that port 3 stay in "ready state" on Extreme side and port remains down on computer side. (no connectivity)

If we desactivate and activate the network interface on the computer (while it remains connected to the swith) the port comes up in 1Gbps Full duplex .

To sum up ; what are the use cases of " configure auto on speed 1000 duplex Full" port configuration?

And what kind of behaviour is expected?
(it' doesn't seems  to advertise the speed to improve the negotiation)

Best regards,

Comment:
There is no problem with the "auto on" mode,  or auto off with speed and duplex whan we want to hard set the network configuration.

[Erik_Auerswald]

Hi,

in my experience, and according to the documentation, the configure port NUMBER auto on speed 1000 duplex full command restricts the advertised link modes to a speed of 1Gbps and full duplex operation.

I have just tested this with an older X450 switch. With just "auto on", all supported link modes are advertised, as shown in the output of ethtool on GNU/Linux:

Link partner advertised link modes: 10baseT/Half 10baseT/Full
                                    100baseT/Half 100baseT/Full
                                    1000baseT/Half 1000baseT/Full

With "auto on speed 1000 duplex full" this is reduced to just one link mode:

Link partner advertised link modes: 1000baseT/Full

In these tests both configurations result in a 1G/full duplex configuration.

Thanks,
Erik

[raphaelp]

Thank you Erik for your answer.

So this command should improve the negotiation of the speed 1Gbps on ports (as intuitive), but in some cases with specific computers (or devices),  it seems to disprut the negociation and lead to "no connectivity" ; for example pluging out/pluging in the cable , rebooting the switch ...

(These problems have'nt been seen using only " configure ports NUMBER auto on" configuration to obtain 1 Gbps connectivity...)

Now , i have to open a case to our reseller...

Thank you again...

[Erik_Auerswald]

Hi,

I would not describe this command as improving the auto-negotiation result.
I would describe it as restricting the acceptable outcomes.

One use case is to ensure either 1Gbps or no link. Another is to limit the speed to, e.g., 100Mbps.

But you are right that if the link negotiates to 1Gbps with just auto on, but to no link with auto on speed 1000 duplex full, something is not OK.

With show port configuration you can see the result of successful auto-negotiation on the EXOS switch. Did you verify that the result with just auto on is full duplex?

Thanks,
Erik

[raphaelp]

Yes Erik,

Using just "auto on" ,the speed was negotiated to 1gbps full duplex without problem.
(seen with "show port NUMBER configuration").
 
Some of the tests with bad  negotiation results  ( with auto on speed 1000 duplex full)  have been reproduced with  laptops using Intel I219 network cards (On W10 OS) , with sub-interfaces with vlan tagging.

But in production we've seen the problem on storage and others servers.

Thanks,

PS:
At first the auto on speed 1000 duplex fullwas used to be sure to negotiate 1Gbps speed....
(like you said it previously)