I'm running a Debian 8 vm on Hyper-V (Win Srv 2012R2) and when I did a dist-upgrade of stable, I lost all network connectivity. Using the console, I was able to see the network interfaces as UP but could not ping any external address.
The dist-upgrade upgraded the kernel to linux-image-3.16.0-4-686-pae (3.16.7-ckt11-1+deb8u2).
I was able to work around this problem by adding 2 legacy network interfaces that are recognized with this new kernel, but I get a much reduced performance.
The Hyper-V modules seem to be loaded fine:
root@rproxy3:~# lsmod | fgrep hv_ hv_utils 17454 0 hv_netvsc 30069 0 hv_storvsc 17048 2 hv_vmbus 27978 6 hyperv_keyboard,hv_netvsc,hid_hyperv,hv_utils,hyperv_fb,hv_storvsc scsi_mod 164132 5 sg,libata,sd_mod,sr_mod,hv_storvsc root@rproxy3:~# dmesg | fgrep hv_ [ 1.303529] hv_vmbus: Hyper-V Host Build:9200-6.2-16-0.16729; Vmbus version:2.4 [ 1.336977] hv_vmbus: registering driver hv_storvsc [ 1.343214] hv_vmbus: registering driver hid_hyperv [ 1.344921] hv_vmbus: registering driver hv_netvsc [ 1.345790] hv_netvsc: hv_netvsc channel opened successfully [ 1.359193] hv_netvsc: hv_netvsc channel opened successfully [ 2.644921] hv_netvsc vmbus_0_13: Send section size: 6144, Section count:170 [ 2.645032] hv_netvsc vmbus_0_13: Device MAC 00:15:5d:01:56:1c link state down [ 3.060851] hv_netvsc vmbus_0_11: Send section size: 6144, Section count:170 [ 3.061034] hv_netvsc vmbus_0_11: Device MAC 00:15:5d:01:56:1b link state down [ 7.672833] hv_vmbus: registering driver hyperv_fb [ 7.893312] hv_vmbus: registering driver hyperv_keyboard [ 8.071484] hv_utils: Registering HyperV Utility Driver [ 8.071487] hv_vmbus: registering driver hv_util
but only the 2 legacy NICs are detected (I have 2 legacy and 2 synthetic NICs configured):
root@rproxy3:~# dmesg | fgrep eth [ 1.351882] net eth0: Digital DS21140 Tulip rev 32 at Port 0xe880, 00:15:5d:01:56:1e, IRQ 9 [ 1.503780] net eth1: Digital DS21140 Tulip rev 32 at Port 0xec00, 00:15:5d:01:56:1f, IRQ 9 [ 11.628988] net eth0: Using EEPROM-set media 100baseTx-FDX [ 11.733151] net eth1: Using EEPROM-set media 100baseTx-FDX
Any idea what to do to debug this further?