Re: Auto-negotiation - Out of business

[poma <pomidorabelisima gmail com>]

On 29.11.2016 13:36, Bjørn Mork wrote:
> Thomas Haller <thaller redhat com> writes:
> > On Tue, 2016-11-29 at 10:23 +0100, Francesco Giudici wrote:
> >
> > > > I would say yes. Half duplex setting is invalid for gigabit network
> > > > speed.
> > >
> > > Yeah, I think so. I should also have got a warning from NM in your
> > > journal logs stating that configuring the 1000Mb/Half failed (search
> > > for
> > > "set-link").
> > > Thanks
> > > Francesco
> >
> > I think then NM should reject such invalid configurations right way.
> > I mean, really reject as invalid, not silently normalize away.
>
> I agree.  There is no way for NM to figure out if the user meant
> 1000/full or 100/half.  So rejecting 1000/half as invalid is the only
> possible action.  Preferably recommending "auto" for users who don't
> know what to do about the rejected config.  No-one should ever force
> speed or duplex without knowing exactly what they do anyway.
>
> (And for those who know what they are doing, there is a 100% probability
> that the *correct* fix is to set the other end to "auto".  Although I
> understand that not all users will have the ability to do that, due to
> the limited range of most cluebats)
>
>
> Bjørn


I guess the same should be considered for a 'speed',
i.e. what is actually supported and advertised,
so e.g. 10 Gb/s is not offered for 1 Gb/s device.


# ethtool enp1s6 | grep modes -A3 | grep -v frame
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Full 
--
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Full 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# egrep duplex\|speed /etc/NetworkManager/system-connections/enp1s6 
duplex=half
speed=10000

# nmcli -f 802-3-ethernet.speed,802-3-ethernet.duplex connection show enp1s6
802-3-ethernet.speed:                   10000
802-3-ethernet.duplex:                  half

# ethtool enp1s6 | egrep Speed\|Duplex
        Speed: 1000Mb/s
        Duplex: Full

~ ~~~~~~~ ~~~~~~ ~ ~~~~~ ~~~~~~~~~~~~~

# egrep duplex\|speed /etc/NetworkManager/system-connections/enp1s6 
duplex=full
speed=10000

# nmcli -f 802-3-ethernet.speed,802-3-ethernet.duplex connection show enp1s6
802-3-ethernet.speed:                   10000
802-3-ethernet.duplex:                  full

# ethtool enp1s6 | egrep Speed\|Duplex
        Speed: 1000Mb/s
        Duplex: Full