Re: [Xen-users] Multicast

[Jayson Vantuyl <jvantuyl@xxxxxxxxxxxxxx>]

I never had a problem but I started mucking about with networking around 3.0.2, so it's hard to tell.

Upgrades are not trivial but they are definitely worth it from the 2.0 series.

IP addresses on bridge devices are universally a bad thing, and is probably the problem.  I don't really know enough about the way the 2.x networking was set up to tell you how to fix this, but it would be under /etc/xen/scripts somewhere if I had to guess.

Xen shouldn't really be able to break multicast.  It may be that the network scripts are broken.  This isn't Xen so much as the scripts that are packaged with it.  This is significant because it can probably be fixed.

Mind you, there's some pretty heavy scripting down there.  I just set it up a null network script and plumb it by hand in my startup scripts.  I don't know how hard this sort of thing would be with your setup.

It's probably time to pay a consultant if this generates revenue.

On May 30, 2007, at 4:07 AM, Stephen Strowes wrote:

Hi,

On Wed, 2007-05-30 at 03:04 -0700, Jayson Vantuyl wrote:

You shouldn't have an IP on xenbr0.  It shouldn't have multicast  

turned on either.  This might be part of the problem.  Did you do  

this or is this happening automatically?

This happens automatically; this is how the network scripts set up

xen-br0.

Note that this is xen 2.0 rather than a more recent version. I've seen

suggestion that multicast didn't work under older versions of Xen. Is

that accurate?

Cheers,

-S.

On May 29, 2007, at 3:22 AM, Stephen Strowes wrote:

Hi,

I've been searching for a solution to my problem, but as yet have not

found it. I've seen suggestion via Google that my version of Xen might

not support what I'm trying to do. Here goes anyway:

I have a bunch of VMs running over a handful of physical machines. I'm

using bridging as an easy way to give domU's access to the network. I

can't get the physical machines to forward the multicast traffic

generated by the virtual machines.

My domU's can all route multicast traffic between each other provided

they're hosted on the same physical machine, but multicast traffic

doesn't seem to be routed over xen-br0 to dom0, nor from dom0 back  

into

the domU's.

Given that I can multicast traffic within the scope of one physical

machine, but not outwith, I assume what I need is to get xen-br0 to

forward multicast traffic. But how?

Below is a bunch of (hopefully) useful information:

dom0 Kernel version:

Linux nsmc16 2.6.11.10-xen0 #1 Thu May 10 15:45:26 BST 2007 i686  

i686 i386 GNU/Linux

example domU kernel version:

Linux nsmc71.dcs.gla.ac.uk 2.6.11.10-xenU #1 Thu May 10 15:48:40  

BST 2007 i686 i686 i386 GNU/Linux

ifconfig outputs:

eth0 Link encap:Ethernet HWaddr 00:12:3F:68:36:96

inet addr:130.209.251.16 Bcast:130.209.255.255 Mask:255.255.240.0

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:12569448 errors:0 dropped:0 overruns:0 frame:0

TX packets:2034982 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:1834684880 (1.7 GiB) TX bytes:594688573 (567.1 MiB)

Base address:0xdcc0 Memory:dfbe0000-dfc00000

xen-br0 Link encap:Ethernet HWaddr 00:12:3F:68:36:96

inet addr:130.209.251.16 Bcast:130.209.255.255 Mask:255.255.255.255

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:11277419 errors:0 dropped:0 overruns:0 frame:0

TX packets:92312 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:1057505519 (1008.5 MiB) TX bytes:7820231 (7.4 MiB)

And an example vif:

vif30.0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:553608 errors:0 dropped:0 overruns:0 frame:0

TX packets:11544969 errors:0 dropped:15753 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:404685898 (385.9 MiB) TX bytes:1246144262 (1.1 GiB)

Might anybody be able to shed some light on this issue? I can't  

upgrade

to a newer version of xen, unless the upgrade is trivial. The  

closest to

my problem which I have seen is:

http://lists.xensource.com/archives/html/xen-users/2006-11/ 

msg00510.html, which received no responses.

Cheers,

-S.

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-- 

Jayson Vantuyl

Systems Architect

Engine Yard

jvantuyl@xxxxxxxxxxxxxx

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