RE: [Xen-users] Weird Network issue

Fischer, Anna
Mon, 03 Aug 2009 19:22:59 -0000

> Subject: [Xen-users] Weird Network issue
>
>
>
> Hi all:
>
> I am pretty new to xen, but ,thanks to you, I am learning fast :)
>
> I have a Dell Poweredge 2950 server running Debian Lenny as Dom0 named
> Asgard
> I have configured three DomU (Loki, Hermod and Thor) with DHCP support.
> All the machines (Dom0 and DomU's) ask for an IP address to a DHCP
> server in the
> Office LAN.
>
> The DHCP server is configured to bind certain IP addresses to the Dom0
> and DomU
> MAC's that works flawlessly.
> When I ping to Asgard, Loki, Hemrod and Thor I have response... but
> when I try to
> make a connection (ssh for example) to Loki from the outside I have a
> connection
> time out message (this happens only with loki DomU, the other ones
> works fine)

Can you maybe run a network packet tracing tool in Dom0 and look at Loki's
virtual network interface and the physical interface to check exactly where
packets go? You can use tcpdump or ethereal. I assume you run Xen in bridging
mode (e.g. check this in /etc/xen/xend-config.sxp)? So you want to find out if
packets are actually received on the physical interface and the virtual
interface of Loki.


> Here's a funny thing... I can SSH to a machine in the outside from
> Loki. If there
> is a connection established between Loki and other host, I can connect
> to Loki
> from the outside. When I disconnect Loki from the host in the Internet
> i can't
> connect to Loki again.
>
> Any ideas?

In case of duplicate MAC/IP addresses it sometimes looks a bit like what you are
seeing...


> Here's the config files of my DomU's
>
> Loki:
> --------------------------------------
> kernel = "/boot/vmlinuz-2.6.26-2-xen-686"
> ramdisk = "/boot/initrd.img-2.6.26-2-xen-686"
> memory = 512
> name = "Loki"
> vif = [ 'mac=00:16:3e:5f:c3:25', 'ip=192.168.1.3' ]

Why do you set this IP address here? Is this the IP address that the DHCP server
assigns?

Can you post your output of "iptables -L" on Dom0?

Can you also post the output of "ifconfig -a" on Dom0?

> dhcp = "dhcp"
> extra = "xencons=tty clocksource=jiffies"
> disk = ['file:/srv/xen/Loki/Loki.img,sda1,w',
> 'file:/srv/xen/Loki/Loki.swap,sda2,w']
> root = "/dev/sda1 ro"
> -------------------------------------
>
>
> Hemrod
> -------------------------------------
> kernel = "/boot/vmlinuz-2.6.26-2-xen-686"
> ramdisk = "/boot/initrd.img-2.6.26-2-xen-686"
> memory = 512
> name = "Hemrod"
> vif = [ "mac=00:22:22:24:6d:fb" ]
> dhcp = "dhcp"
> extra = "xencons=tty clocksource=jiffies"
> disk = ['file:/srv/xen/Hermod/Hermod.img,sda1,w',
> 'file:/srv/xen/Hermod/Hermod.swap,sda2,w']
> root = "/dev/sda1 ro"
> -------------------------------------
>
> Thor
> -------------------------------------
> kernel = "/boot/vmlinuz-2.6.26-2-xen-686"
> ramdisk = "/boot/initrd.img-2.6.26-2-xen-686"
> memory = 512
> name = "Thor"
> vif = [ "mac=00:22:22:24:6e:00" ]
> dhcp = "dhcp"
> extra = "xencons=tty clocksource=jiffies"
> disk = ['file:/srv/xen/Thor/Thor.img,sda1,w',
> 'file:/srv/xen/Thor/Thor.swap,sda2,w']
> root = "/dev/sda1 ro"
> --------------------------------------
>
>
> Thanks in advance
>
> Zeke
>
> PD: Sorry my bad english :-S
>
>
>
>
>
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