[Xen-users] Bridging

Wendell Dingus
2008-10-04T12:21:19Z

We just installed CentOS 5.2 on a SuperMicro server and went to install a VM and
the "share a physical network device" option had nothing that could be
selected. I''m thinking that possibly it has to do with the
peculiarities of the NICs in this box, maybe...

Before the domu is started:

# brctl show
bridge name bridge id STP enabled interfaces
virbr0 8000.000000000000 yes
xenbr0 8000.feffffffffff no peth0
vif0.0

# /etc/xen/scripts/network-bridge status
============================================================
7: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
link/ether 00:30:48:c4:55:fa brd ff:ff:ff:ff:ff:ff
inet 204.87.213.163/24 brd 204.87.213.255 scope global eth0
inet6 fe80::230:48ff:fec4:55fa/64 scope link
valid_lft forever preferred_lft forever
14: xenbr0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue
link/ether fe:ff:ff:ff:ff:ff brd ff:ff:ff:ff:ff:ff

bridge name bridge id STP enabled interfaces
virbr0 8000.000000000000 yes
xenbr0 8000.feffffffffff no peth0
vif0.0

204.87.xx.0/24 dev eth0 proto kernel scope link src 204.87.xx.163
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1
169.254.0.0/16 dev eth0 scope link
default via 204.87.xx.1 dev eth0

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
204.87.xx.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
0.0.0.0 204.87.xx.1 0.0.0.0 UG 0 0 0 eth0
============================================================

After it is started:

# brctl show
bridge name bridge id STP enabled interfaces
virbr0 8000.0a9c119ed9dd yes vif10.0
tap0
xenbr0 8000.feffffffffff no peth0
vif0.0

The odd thing I noticed, graphically in system-config-network actually, is that
peth0 seems to be associated with eth1 instead of eth0. Might just be an oddity
of how this graphical utility represents things, not sure. The eth0 hardware
(according to this pointy-clicky tool) is e1000e and the eth1 hardware is
"Intel Corporation 80003". Physically the eth0 interface has a cable
and nothing in the other. Yet in the hardware tab of this tool it shows peth0 as
being the "Intel Corporation 80003" hardware. Like it''s
linked to the physical eth1(?)

Since I couldn''t select it initially I went ahead and completed the
install with default networking then edited the config and changed the vif line
to have ,bridge=xenbr0 instead of the ,bridge=virbr0,script=vif-bridge that was
put in there automatically. In neither case is the domu successfully bridged
though.

# lspci | grep -i eth
06:00.0 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit Ethernet
Controller (Copper) (rev 01)
06:00.1 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit Ethernet
Controller (Copper) (rev 01)

# grep -i eth /etc/modprobe.conf
alias eth0 e1000e
alias eth1 e1000e
alias peth0 e1000e

Thanks.

PS. I installed both another CentOS domu as well as a Windows XP one. On the XP
one I got the newest compiled PV drivers and installed those. Afterwards I have
both a Realtek and a Xen NIC defined in Windows. The Realtek one says it has a
cable plugged in but the Xen one does not. Not sure if that''s a symptom
of the previous problem leaking through or if I did something wrong setting that
up in Windows.