[Xen-users] Strangness with IP's

[Rus Foster <twattycake@xxxxxxxxx>]

We've got a problem we've not come across before. We are running xen
3.4.3 on a known good configuration

We have the subnet 109.169.72.128/25 pointing to a server with
109.169.72.129 as the default GW

Random IP's in the subnet will not route from a domU (Xen PV and Xen
HVM))to the default gw

An IP will work on one domU but not another

If the IP is bound to eth0:0 on the dom0 it works fine.

Our configuration file for an effected VM is

kernel     = '/boot/solus-vmlinuz'
ramdisk    = '/boot/solus-initrd.img'
#bootloader = '/usr/bin/pygrub'
extra      = ''
memory     = 512
hostname   = 'blah'
cpu_weight = 256
name       = 'vm5952'
vif        = ['ip=109.169.72.235, vifname=vifvm5952.0, mac=00:16:3e:af:ec:d7']
vnc        = 0
vcpus      = 4
vncviewer  = 0
serial     = 'pty'
disk       = ['phy:/dev/VolGroup00/vm5952_img,xvda1,w',
'phy:/dev/VolGroup00/vm5952_swap,xvda2,w']
root       = '/dev/xvda1 ro'

It boots fine to the console and within the VM the network
configuration looks sane

domU

sh-3.00# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:16:3E:AF:EC:D7
          inet addr:109.169.72.235  Bcast:109.169.72.255  Mask:255.255.255.128
          inet6 addr: fe80::16:3eff:feaf:ecd7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1362 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:88977 (86.8 KiB)  TX bytes:776 (776.0 b)
          Interrupt:24


sh-3.00# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
109.169.72.128  0.0.0.0         255.255.255.128 U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
0.0.0.0         109.169.72.129  0.0.0.0         UG        0 0          0 eth0

BUT


sh-3.00# ping -c 1 109.169.72.129
PING 109.169.72.129 (109.169.72.129) 56(84) bytes of data.

--- 109.169.72.129 ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms


On the node itself


[root@8 xen]# brctl show
bridge name     bridge id               STP enabled     interfaces
eth0            8000.0025901d7134       no              vifvm5952.0
                                                                peth0



[root@8 xen]# xm info
host                   : 8.xn.nj.damnvps.com
release                : 2.6.18-194.32.1.el5xen
version                : #1 SMP Wed Jan 5 18:44:24 EST 2011
machine                : x86_64
nr_cpus                : 16
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 2
cpu_mhz                : 2400
hw_caps                :
bfebfbff:2c100800:00000000:00000740:009ee3fd:00000000:00000001:00000000
virt_caps              : hvm
total_memory           : 98294
free_memory            : 72498
node_to_cpu            : node0:0-15
node_to_memory         : node0:72498
xen_major              : 3
xen_minor              : 4
xen_extra              : .3
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)
cc_compile_by          : root
cc_compile_domain      : gitco.tld
cc_compile_date        : Sat Jan 22 14:01:09 CET 2011
xend_config_format     : 4

Any ideas are welcome...

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