Re: xen and networking problems

[brook%biology.nmsu.edu@localhost (Brook Milligan)]

Manuel Bouyer writes:
 > Please check with netstat if you have interrupt for this device.

# vmstat -i
interrupt                                     total     rate
vcpu0 ioapic0 pin 17                           1205        9
vcpu0 ioapic0                                  2644       21
vcpu0 ioapic0                                    10        0
vcpu0 ioapic0                                   485        3
vcpu0 clock                                   13057      104
vcpu0 xenbus                                     53        0
Total                                         17454      139

Note that the ioapic0 pin 17 device corresponds to the fxp0 network
interface.  This command was run while pinging the interface, and the
number of interrupts increases each time the command is run.  I
presume this means that the hardware is generating interrupts as
packets arrive.

In addition, the results of netstat are below.  The number of packets
in increased with each run of the command and the number of packets
out increased if I pinged from this machine (although outgoing pings
always resulted in 'ping: sendto: Host is down' errors).

# netstat -i
Name  Mtu   Network       Address              Ipkts Ierrs    Opkts Oerrs Colls
fxp0  1500  <Link>        00:30:48:23:3a:81     1702     0       14     0     0
fxp0  1500  176.16.0.2/24 172.16.0.2            1702     0       14     0     0
fxp0  1500  fe80::/64     fe80::230:48ff:fe     1702     0       14     0     0
lo0   33184 <Link>                                 0     0        0     0     0
lo0   33184 127/8         localhost                0     0        0     0     0
lo0   33184 localhost/128 ::1                      0     0        0     0     0
lo0   33184 fe80::/64     fe80::1                  0     0        0     0     0

 > You could also run tcpdump and see if you receive some packets.

tcpdump never captured any packets under these tests, which were all
done without creating the bridge0 interface.  (The bridge was present
when I generated output for earlier posts.)  Before I disabled
bridge0, however, tcpdump reported only STP packets.  For these tests
I disabled the bridge to make sure that it wasn't interfering with the
primary network interface.

Does all of this mean that the packets are arriving at the hardware
interface, are being partially processed by the kernel network stack,
but are being lost somewhere along the way before making it to any
applications?

What else can be done to track down what is going on here?

By the way, without a serial console is there a way to capture the
boot messages from the xen hypervisor?  Alternatively, is there a way
to pause the boot process so I can review the messages before they
scroll off the screen?

Thanks again for your help.

Cheers,
Brook