Ethernet troubles with X230

Hi,

I have a problems with ethernet on my laptop (X230). pciconf(8)
identifies the device as Intel 82579LM Gigabit Network Connection
(Lewisville). 

1. Resuming after a long suspend (~5hr), sometimes the
machine can't get a DHCP IP. 

2. After suspend, the ethernet device starts reporting no carrier,
eventhough the cables are plugged in and if I plug it to a different
box, they would work

I can reproduce both on 12.0-CURRENT #17 r336576. But not sure when they started.

I have seen this behaviour with 2 routeres running three firmwares at
the other end.
1. Easybox (linux 2.x?)
2. Edgerouter lite running stock fw (linux 2.x) and 12-CURRENT (~3 months old)

For Problem (1) DHCP lease: 
ifconfig shows:
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=81249b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LRO,WOL_MAGIC,VLAN_HWFILTER>
	ether xx:xx:xx:xx:xx:xx
	inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255 
	media: Ethernet autoselect (1000baseT <full-duplex>)
	status: active
	nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

It still can't get an ip if I invoke service netif restart

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=81249b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LRO,WOL_MAGIC,VLAN_HWFILTER>
	ether xx:xx:xx:xx:xx:xx
	inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255 
	media: Ethernet autoselect (1000baseT <full-duplex>)
	status: active
	nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

If I try running dhclient manually,

[dhananjay:~] 1 % sudo dhclient em0
dhclient already running, pid: 14305.
exiting.
[dhananjay:~] 1 % sudo kill 14305
[dhananjay:~] % sudo dhclient em0
DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 6
DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 6
DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 10
DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 13
DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 17
DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 9
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

For (2) For status no carrier
em0: flags=8c03<UP,BROADCAST,OACTIVE,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=81249b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LRO,WOL_MAGIC,VLAN_HWFILTER>
	ether xx:xx:xx:xx:xx:xx
	media: Ethernet autoselect
	status: no carrier
	nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

and dmesg keeps repeating 
em0: TX(0) desc avail = 1024, pidx = 0
em0: TX(0) desc avail = 1024, pidx = 0
em0: TX(0) desc avail = 1024, pidx = 0
em0: TX(0) desc avail = 1024, pidx = 0


The only solution I have found so far is to just reboot the laptop and
then everything starts working.  FWIW the router led never blinks (no
data transfers during DHCPDISCOVER). I am not sure how to debug this.

-
Dhananjay Balan