Re: [Xen-users] setting up private networking between dom0 and domU?

[Fernando Maior <fernando.souto.maior@xxxxxxxxx>]

On 1/22/06, Jack Snodgrass <mylinuxguy@xxxxxxxxx> wrote:
> I am trying to set up dom0 <->domU networking using a
> virtual switch, a tap device on dom0 and a NIC on domU.
>
> I have domU <-> domU connectvity throguth a virtual switch.
> I also have domU <-> eth0 using a bridge. I'm using Xen 3.0
> from Fedora FC5.
>
> I used these commands to set up the tap0 and sw2 device:
>
>   # creating switch 2
>   brctl addbr sw2
>   brctl stp sw2 off
>   brctl setfd sw2 0
>   ifconfig sw2 up
>
>  # creating tun/tap device
>  tunctl -t tap0
>
> # adding tun/tap device to bridge
> brctl addif sw2 tap0
>
> # configuring tap0 device
> ip address add 192.168.3.2/29 dev tap0
> ifconfig tap0 up
>
> ifconfig shows:
> [root@xen xen]# ifconfig sw2
> sw2       Link encap:Ethernet  HWaddr A6:44:26:ED:AC:5F
>           inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:259 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:7252 (7.0 KiB)  TX bytes:468 (468.0 b)
>
> [root@xen xen]# ifconfig tap0
> tap0      Link encap:Ethernet  HWaddr A6:44:26:ED:AC:5F
>           inet addr:192.168.3.2  Bcast:192.168.3.7  Mask:255.255.255.248
>           inet6 addr: fe80::a444:26ff:feed:ac5f/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:687 overruns:0 carrier:0
>           collisions:0 txqueuelen:500
>           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
>
> (NOTE: look at the dropped:687 packets for tap0. I don't know what that 
> means...
> other than its bad.  )
>
> If I to a tcpdump -n -i sw2, and ping the tap0 device from my domU
> instance, I see:
> [root@xen xen]# tcpdump  -n  -i sw2
> tcpdump: WARNING: sw2: no IPv4 address assigned
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on sw2, link-type EN10MB (Ethernet), capture size 96 bytes
> 21:24:15.428994 arp who-has 192.168.3.2 tell 192.168.3.1
> 21:24:16.427484 arp who-has 192.168.3.2 tell 192.168.3.1
> 21:24:17.427558 arp who-has 192.168.3.2 tell 192.168.3.1
> 21:24:18.439598 arp who-has 192.168.3.2 tell 192.168.3.1
> 21:24:19.439673 arp who-has 192.168.3.2 tell 192.168.3.1
> 21:24:20.439724 arp who-has 192.168.3.2 tell 192.168.3.1
>
> the dom0 device does not answere the ARP Who-Has request. The domU box
> has the correct netmask and broadcast address defined.
>
> I set up sw1 in a similar fashion as sw2. My two domU machine are able
> to talk over sw1 just fine.
>
> What am I missing?
>
> Thanks - jack
>
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>

Hi,
Did you realize you have same MAC address for both sw2 and
tap0? What about your eth0? May be you have a conflict up
there...

--
Bye,
Fernando Maior
LPIC/1(31908)
LinuxCounter(391325)

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