[fedora-virt] Problem with network when starting VM

[fedora.bobd at dfgh.net]

Hi,

When I start a new VM, my host network stops functioning, and then I 
have persistent issues with the host network thereafter, even after 
shutting down all VMs.

The symptom of my network issues is that it intermittently goes down. 
ping returns "Destination Host Unreachable" even for hosts on my local 
network, although my routes still look good according to 'route -rn'. I 
believe my network is flooded with STP packets at this point and all my 
switches will go down shortly thereafter. I can recover for a while by 
unplugging/replugging network cable but the problem comes back after a 
few minutes. A reboot will clear it up.

On the host dmesg output, I see the following when this occurs:
http://pastebin.com/dpPk53d9

I am using the alx driver (AR816x/AR817x network controller) with Fedora 19.

I have attached output of 'brctl show', 'ip link', and 'ip address'. I 
use NetworkManager, and disable WiFi manually before using libvirt.

I would very much appreciate any guidance.

Thanks,
      Bob



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bridge name	bridge id		STP enabled	interfaces
virbr0		8000.52540075e7d6	yes		virbr0-nic
virbr1		8000.525400b9370b	yes		virbr1-nic
virbr2		8000.525400a2f3ae	yes		virbr2-nic
vnet0		8000.dc0ea1f4b51e	yes		em1
-------------- next part --------------
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vnet0 state UP mode DEFAULT qlen 1000
    link/ether dc:0e:a1:f4:b5:1e brd ff:ff:ff:ff:ff:ff
3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN mode DEFAULT qlen 1000
    link/ether 9c:4e:36:2f:ec:b8 brd ff:ff:ff:ff:ff:ff
5: virbr2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT 
    link/ether 52:54:00:a2:f3:ae brd ff:ff:ff:ff:ff:ff
6: virbr2-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr2 state DOWN mode DEFAULT qlen 500
    link/ether 52:54:00:a2:f3:ae brd ff:ff:ff:ff:ff:ff
7: virbr1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT 
    link/ether 52:54:00:b9:37:0b brd ff:ff:ff:ff:ff:ff
8: virbr1-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr1 state DOWN mode DEFAULT qlen 500
    link/ether 52:54:00:b9:37:0b brd ff:ff:ff:ff:ff:ff
9: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT 
    link/ether 52:54:00:75:e7:d6 brd ff:ff:ff:ff:ff:ff
10: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN mode DEFAULT qlen 500
    link/ether 52:54:00:75:e7:d6 brd ff:ff:ff:ff:ff:ff
13: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT 
    link/ether dc:0e:a1:f4:b5:1e brd ff:ff:ff:ff:ff:ff
-------------- next part --------------
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vnet0 state UP qlen 1000
    link/ether dc:0e:a1:f4:b5:1e brd ff:ff:ff:ff:ff:ff
    inet6 fe80::de0e:a1ff:fef4:b51e/64 scope link 
       valid_lft forever preferred_lft forever
3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN qlen 1000
    link/ether 9c:4e:36:2f:ec:b8 brd ff:ff:ff:ff:ff:ff
5: virbr2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether 52:54:00:a2:f3:ae brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.1/24 brd 192.168.200.255 scope global virbr2
       valid_lft forever preferred_lft forever
6: virbr2-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr2 state DOWN qlen 500
    link/ether 52:54:00:a2:f3:ae brd ff:ff:ff:ff:ff:ff
7: virbr1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether 52:54:00:b9:37:0b brd ff:ff:ff:ff:ff:ff
    inet 192.168.250.1/24 brd 192.168.250.255 scope global virbr1
       valid_lft forever preferred_lft forever
8: virbr1-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr1 state DOWN qlen 500
    link/ether 52:54:00:b9:37:0b brd ff:ff:ff:ff:ff:ff
9: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether 52:54:00:75:e7:d6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
10: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN qlen 500
    link/ether 52:54:00:75:e7:d6 brd ff:ff:ff:ff:ff:ff
13: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP 
    link/ether dc:0e:a1:f4:b5:1e brd ff:ff:ff:ff:ff:ff
    inet 172.16.1.31/16 brd 172.16.255.255 scope global vnet0
       valid_lft forever preferred_lft forever
    inet6 fe80::de0e:a1ff:fef4:b51e/64 scope link 
       valid_lft forever preferred_lft forever