iface is not coming back up fully after ifdown

[Maxim Sloyko]

On Fri, Mar 31, 2017 at 11:39 AM, Milton Miller II <miltonm at us.ibm.com> wrote:
> On  03/31/2017 around 12:25PM in some timezone, Maxim Sloyko wrote:
>
>>I ran into what I think is a bug with networking interface, but I'm
>>not sure what exactly is broken.
>>
>>If you bring the interface down (ifconfig eth1 down) and then try to
>>bring it up (ifconfig eth1 up) it does not fully recover. That is, it
>>shows up as RUNNING in ifconfig, you can set up ip/netmask/gw and try
>>sending packets, but nothing ever shows up at the other end of the
>>wire.
>>
>>If you unplug the ethernet cable and then plug it back in (thus
>>resetting the phy, I believe?), the interface starts working again. I
>>tried this with Zaius and  EVB (which have different PHYs) and it's
>>broken like this on both.
>>
>>I suspect that as part of IFF_UP flag handling the kernel (drivier?)
>>needs to also reconfigure the link with PHY, but it's not doing that.
>>I don't know how this works in the kernel though, so I would
>>appreciate any pointers to where I should start digging.
>>
>
> Is this with a real PHY or an NC-SI channel?

This is with a real PHY, I haven't tried this with NC-SI yet.

>
> Do you see messages showing the link coming up after ifconfig up?

Yes, after I run "ifconfig eth1 .... up" I see these messages:

IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
root at zaius:~# IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready


>
> Be aware that for NC-SI attached, the kernel always enables the
> state to running to be able to send and receive MAC frames to
> manage the connection, and there is a secondary interface or
> interface state that reflects the true link state.
>
> Sorry I don't have the experience or resources to help further.
>
> milton
>



-- 
Maxim Sloyko