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Re: [Xen-users] Problem with network in DomU with SLES 11 SP2

  • To: xen-users@xxxxxxxxxxxxx
  • From: Alexandre Kouznetsov <alk@xxxxxxxxxx>
  • Date: Thu, 14 Jun 2012 14:14:56 -0500
  • Delivery-date: Thu, 14 Jun 2012 19:16:13 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>

El 13/06/12 21:57, Schenk, Thomas escribió:
So for example:


Physical device: em1 is assigned IP address

There are VLANs created using vconfig as follows: vconfig add em1 213
(and so on for all 5 vlans)
Isn't supposed to belong to VLAN211? You just binded it to vlan213.

I do not work with SLES, but in my case, if Dom0 shall have a IP on a bridge, I assign the IP to the bridge itself, not to the physical interface which is member of the bridge. Let me illustrate:

# brctl show
xenbr01         8000.0026b9874553       no              eth0

# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:26:b9:87:45:53
          inet6 addr: fe80::226:b9ff:fe87:4553/64 Scope:Link

# ifconfig xenbr01
xenbr01   Link encap:Ethernet  HWaddr 00:26:b9:87:45:53
          inet addr:  Bcast:  Mask:
          inet6 addr: fe80::226:b9ff:fe87:4553/64 Scope:Link

# brctl show
bridge name bridge id STP enabled interfaces
br211 8000.047d7b16089b yes vlan211
Please show the configuration of vlan211 and vlan217.
cat /proc/net/vlan/config

and at the DomU level, vif6.0 shows as eth0 and vif6.1 shows as eth1.
Please show the Xen configuration file for DomU. Particularly the "vif=" line.

In this case, the DomU has an ip address of assigned to eth0.
Please show the output of "ifconfig eth0" from DomU and your DomU's routing table.

My problem is this:

 From Dom0, I can ping my gateway and since the switch
knows about all of the VLANS, I can also ping,, etc. so basically, I can see the world, however, if I do
an arping -I em1 to any of the network gateways except for my default
gateway, I get no response.

 From DomU, I can ping nothing. Not the gateway of or
anything else.

If from Dom0, I run a tcpdump -i br217, and from DomU, starting trying
to ping my gateway, I see the following:

15:41:35.453693 arp who-has tell
As I understand, is reachable on VLAN217, but does not responds properly to ARP requiests. Maybe it's reproducible from Dom0, so we can isolate it as router's issue? You could configure you Dom0 to have a valid IP on VLAN217 and run arping, but I wish to suggest you to simplify your test field first, see below.

Who is 172.16.*.2, a Layer 3 switch?

The setup description is little bit confusing, maybe the real problem has something so do with that. Let me suggest you to simplify your test setup. If it works, you can add complexity until you get what you need, test on each step, so if you encounter a problem it can be isolated. Consider doing the following:

Disable/shutdown temporarily all your network bridges and VMs.
On Dom0, set up br211, make physical interface vlan211 (that's how they call it in SLES?) to be member of it. Assign a valid IP address to br211 on Dom0. Check with ping and traceroute, if you router's different IP's are reachable.

On Dom0, set up br217, make physical interface vlan217 to be member of it. Do not assign IP from to Dom0 yet.

Config your test DomU to have 1 network interface within br217, assign a IP to that interface within DomU. Test if is reachable from DomU.

If success, add another bridge to the setup, and so on. If not, we can torubleshoot in detail (personally I don't trust L3 switches for routing).

Alexandre Kouznetsov

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