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RE: [Xen-users] Bonding & xenbr0

To: "Gerhard Spiegl" <gspiegl@xxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] Bonding & xenbr0
From: "Geoff Wiener" <gwiener@xxxxxxxxxxxxxxx>
Date: Tue, 24 Jun 2008 19:04:47 +0100
Cc: Stephan Seitz <s.seitz@xxxxxxxxxxxx>
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Thread-topic: [Xen-users] Bonding & xenbr0
Hi Gerhard;

Unfortunately I have never tried to use mode=1 so I would only be speculating 
to suggest that maybe the bridge is causing the same mac to be broadcast from 
both of the two interfaces.  You could test further by running tcpdump on the 
bridge and each interface to try to see what's going on in there...  As an 
alternative configuration that I can talk about from experience, I use 802.3ad 
with bond mode=4.  To use this you will need to get your Cisco engineers 
involved to configure a port group and to put the physical ports into it on the 
switch. S/he might be happy to help to resolve your mutual issue. I have used 
this with both Cisco and Dell Power Connect switches with Xen 3.2.1 (Intel and 
Broadcom adapters) and so far I have not had any issues.  This configuration 
provides both load balancing and failover using (by default) a source mac hash 
algorithm.

As for the xend network-bridge startup script - I have broken that (replaced it 
with network-dummy) and just use the native networking in Dom0 to create my own 
bonds, vlans and bridges.  Most of the info I used to come up with the 
configuration is from this list.

Sorry I couldn't be of more help with your specific issue.  If you find a 
solution to mode=1 I would be curious to know the answer...

G

-----Original Message-----
From: Gerhard Spiegl [mailto:gspiegl@xxxxxx] 
Sent: 24 June 2008 1:32 PM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Cc: Stephan Seitz; Geoff Wiener
Subject: Re: [Xen-users] Bonding & xenbr0

Hi,

thanks for your answers!
The bonding mode used is 1 (active-backup) with eth0 as primary interface:

alias bond0 bonding
options bond0 mode=1 primary=eth0 updelay=40000 miimon=100 max_bonds=2

It's a Cisco Catalyst without any specific bonding configuration since
active-backup should just work (well, at least I thought so ..)

Without the xen bridge there are no errors (according to the network
admin). Also before the bridge comes up, bond0, eth0 and eth1 have the
same MAC inherited from eth0 (the way it should be).

Another mess (but not the actual problem) is if xend is not enabled at
boot time but invoked manually via "service xend start", the bridge
comes up but attaches (p)eth0 instead of (p)bond0. In fact pbond0 isn't
even created as it should cause of the "netdev=bond0" param.

Any ideas?

Here are the relevant network-scripts:

/etc/sysconfig/network-scripts/ifcfg-eth0:
-----------------------------
#
DEVICE=eth0
BOOTPROTO=none
HWADDR=
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no
TYPE=Ethernet

/etc/sysconfig/network-scripts/ifcfg-eth1:
-----------------------------
#
DEVICE=eth1
BOOTPROTO=none
HWADDR=
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no
TYPE=Ethernet

/etc/sysconfig/network-scripts/ifcfg-bond0:
-----------------------------
DEVICE=bond0
BOOTPROTO=none
HOSTNAME=ols011
IPADDR=172.27.100.121
NETMASK=255.255.240.0
GATEWAY=172.27.111.254
ONBOOT=yes
USERCTL=no
PEERDNS=no
IPV6INIT=no
TYPE=Ethernet




Stephan Seitz wrote:
> Hi,
> 
> I assume your switches expect another protocol. Depending on the
> mode parameter of the bonding module NICs are getting different or
> same MAC.
> 
> Did you encounter the problem without a bridge on bond0?
> 
> cheers
> 
> Stephan
> 
> 
> Gerhard Spiegl schrieb:
>> Hi List!
>>
>> This is my first post on this list so let me say hello to all here!
>>
>> I'm trying to set up HA xen VMs on RHEL 5.2 with Red Hat Cluster Suite.
>> XEN version used is original Red Hat packaged xen-3.0.3-64.el5_2.1.
>>
>> Setup is the following:
>>
>> eth0 + eth1 ==> bond0  (public interface, connected to two core
>> switches with one vlan)
>> eth2  (private interface connected to rack mounted 100Mbit switch for
>> cluster interconnect)
>>       (this will be eth2 + eth3 ==> bond1 in future)
>>
>> The xen network is working fine after adding "netdev=bond0" to the
>> (network-script ...) line
>> in xend-config.sxp - no other changes were made.
>>
>> But: Yesterday the network administrator complained about error
>> messages in the
>> switch logs caused by multiple interfaces having MAC address
>> FE:FF:FF:FF:FF:FF since
>> XEN was set up.
>> The only public interface with a configured IP is bond0 with the MAC
>> of enslaved eth0
>> so why is this strange MAC (FE:FF..) seen on the switch? We are also
>> wondering why
>> eth0 and eth1 do have this MAC. Is there an issue with bonding and xen
>> bridging?
>>
>> Output of ifconfig is attached, if you need more information, please
>> let me know.
>>
>> I would be pleased if anyone could point me to a right direction -
>> google didn't help.
>>
>> regards
>> Gerhard
>>
>>
>>
>>
>>
>> ------------------------------------------------------------------------
>>
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> 
> 
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