Unplugged Ethernet Interface listed as RUNNING

[Ian Lepore]

On Wed, 2017-09-27 at 07:06 -0700, Russell Haley wrote:
> Hi,
> 
> I'm poking at stuff on my Hummingboard. I was using my wired
> interface
> ffec0 and then switched over to my wifi stick. After unplugging the
> etherent cable, ifconfig still lists the ffec0 interface as UP and
> RUNNING still has an ip address even though it was assigned via dhcp.
> This was consistent over multiple attempts with and without the wifi
> stick invovled. The status indication correctly shows no carrier when
> the ethernet is unplugged.
> 
> I did a comparison to my BBB running Debian Jessie and when the
> ethernet cable is removed, the interface is still listed as UP but
> not
> as RUNNING (although there is no status indication in Linux).
> 
> My question: Should FreeBSD be showing the ffec0 interface as RUNNING
> even though there is no cable plugged in? Should the DHCP aquired ip
> address be removed from the ifconfig listing when the ethernet cable
> is unplugged?
> 

The re0 and re1 interfaces on my x86 desktop system behave the same
way; I think all of that is normal.  In freebsd, the RUNNING flag is
commented in the header file as "[driver] resources allocated".

You definitely wouldn't want the interface to lose its IP address just
because the connection is down, that could lead to all your open tcp
connections dying because of a momentary loss of carrier.

-- Ian

> Thanks
> 
> Russ
> 
> root at imx6:~ # ifconfig
> ffec0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0
> mtu 1500
>         options=80008<VLAN_MTU,LINKSTATE>
>         ether d0:63:b4:00:8f:19
>         hwaddr d0:63:b4:00:8f:19
>         inet 192.168.2.2 netmask 0xffffff00 broadcast 192.168.2.255
>         media: Ethernet autoselect (none)
>         status: no carrier
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
>         options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
>         inet6 ::1 prefixlen 128
>         inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
>         inet 127.0.0.1 netmask 0xff000000
>         groups: lo
>         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
> wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0
> mtu 1500
>         ether 60:a4:4c:ec:c9:a5
>         hwaddr 60:a4:4c:ec:c9:a5
>         inet 192.168.2.62 netmask 0xffffff00 broadcast 192.168.2.255
>         groups: wlan
>         ssid Haleys_DownStairs channel 8 (2447 MHz 11g) bssid
> ac:9e:17:67:85:90
>         regdomain FCC country US authmode WPA2/802.11i privacy ON
>         deftxkey UNDEF AES-CCM 2:128-bit txpower 30 bmiss 7 scanvalid
> 60
>         protmode CTS wme roaming MANUAL
>         media: IEEE 802.11 Wireless Ethernet DS/1Mbps mode 11g
>         status: associated
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
> 
> 
> root at imx6:~ # cat /etc/rc.conf
> hostname="imx6"
> ifconfig_DEFAULT="DHCP"
> wlans_run0="wlan0"
> ifconfig_wlan0="WPA SYNCDHCP"
> sshd_enable="YES"
> sendmail_enable="NONE"
> sendmail_submit_enable="NO"
> sendmail_outbound_enable="NO"
> sendmail_msp_queue_enable="NO"
> growfs_enable="YES"
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