This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-users] bonding + vlans ALMOST working, NO ARP

To: Eli Criffield <elicriffield@xxxxxxxxx>
Subject: Re: [Xen-users] bonding + vlans ALMOST working, NO ARP
From: Tomasz Chmielewski <mangoo@xxxxxxxx>
Date: Fri, 01 Sep 2006 16:33:06 +0200
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Delivery-date: Fri, 01 Sep 2006 07:34:21 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <18e3f33d0608310859o319e5536p24fef2bd3d2cd004@xxxxxxxxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <18e3f33d0608310859o319e5536p24fef2bd3d2cd004@xxxxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird (X11/20060814)
Eli Criffield wrote:
I'm very close to getting bonding + vlans + bridging to work.

The only part that's not working is ARP.

Why i have no idea? But if put in an arp entry for the default route
manually with 'arp -s 00:00:0C:07:0C:C9' everything
works great.  (Everything that goes though the default route anyway).

Now if i run tcpdump on any of the interfaces involved in the bridge,
eth0, eth1, bond0, vlan151 or vlan151-br, vif0,0, or veth0 (i don't
rename any interfaces) then it works fine, I get arp replays. But if i
use 'ip' to turn on promisc any of the interfaces it doesn't work,
just like it doesn't work without promisc off.

The script is a little diffrent then the last one i posted, I'll atach
it at the end.

Basically I'm combining eth0 and eth1 into bond0, add vlans to bond0
named "vlanXXX"  make a bridge named vlanXXX-br and add vlanXXX to it,
and then domU's are started with bridge=vlanXXX-br in there xen config
file to decide what vlan they should be part of.

So what is tcpdump doing to make arp work???

Doesn't it look like this issue:


3.3. Why does my new domain receive no network traffic until after it initiates an outgoing connection?

This is an issue that occurs under the following circumstances:

* You do not specify the domain's MAC address, causing a random MAC address to be selected at domain creation time
    * The upstream router has a local ARP cache

When a domain is destroyed, the host system's ARP cache is purged of addresses for the defunct virtual NIC. If the domain is recreated it is likely to be allocated a different random MAC address. This is no problem for the host machine, but the external switch/router still knows the "old" MAC address. The switch/router requires an outbound packet to the outside world to implicitly eradicate the old ARP-cache entry. This is not really Xen's fault at all, just a property of the implementation of ARP resolution.

Tomasz Chmielewski

Xen-users mailing list

<Prev in Thread] Current Thread [Next in Thread>