Bug 142019

Summary: [em] em needs "ifconfig em0 down up" when link was gone
Product: Base System Reporter: Andre.Albsmeier
Component: kernAssignee: jfv
Status: Closed FIXED    
Severity: Affects Only Me CC: sbruno
Priority: Normal Keywords: IntelNetworking
Version: 7.2-STABLE   
Hardware: Any   
OS: Any   

Description Andre.Albsmeier 2009-12-25 18:30:01 UTC
The em0 interface mentioned above is connected to another 100MBit
Ethernet device through a cross cable. Everything works until
this other device is powered down and up again. In this case
one can't talk to this device anymore:

gate:~>ping 192.168.128.66
PING 192.168.128.66 (192.168.128.66): 56 data bytes
ping: sendto: No buffer space available
ping: sendto: No buffer space available
ping: sendto: No buffer space available
...

After running "ifconfig em0 down up" on the FreeBSD box all is
well (pinging and transferring files) until the other device
has been  powered down and up again.

The very same hardware didn't show this problem in 6-STABLE
so I assume something has changed in the em driver.

Fix: 

Unknown, possibly a MFC of the em driver from 8-STABLE
might be enough, see:
 
http://lists.freebsd.org/pipermail/freebsd-stable/2009-November/052887.html
How-To-Repeat: 
See above. I tried with a satellite dish receiver and another
fxp-based machine as the other device.
Comment 1 Mark Linimon freebsd_committer freebsd_triage 2009-12-26 07:41:55 UTC
Responsible Changed
From-To: freebsd-bugs->freebsd-net

Over to maintainer(s).
Comment 2 Andre Oppermann freebsd_committer 2010-08-23 18:40:59 UTC
Responsible Changed
From-To: freebsd-net->jfv

Over to maintainer.
Comment 3 Sean Bruno freebsd_committer 2015-06-30 17:35:39 UTC
I don't see this happen when connected to a 100mbit switch.  Assuming this is closed as fixed.