[Users] OpenVZ Multicast Questions

[Peter Hinse]

nimbus 4321 wrote:

> Following the thread at 
> http://forum.openvz.org/index.php?t=msg&goto=21090 
> <http://forum.openvz.org/index.php?t=msg&goto=21090> , the VEs are 
> configured to use veth, with the veths connected using a bridge (vzbr0).
> The routing tables are setup so that the (unicast) IPs for the VEs are 
> routed via the bridge. This all works fine for unicast in all scenarios 
> - i.e. between the VEs, between the hosting HN and VEs, and between 
> other nodes and the VEs. It also works fine for multicast between the 
> VEs if they are on the same HN. However, it does not work for multicast 
> from the HNs to the VEs they are hosting, or from other nodes (including 
> VEs on other nodes) to the VEs.
> 
> Steps carried out so far:
> 
> In attempting to get multicast working between VEs on separate machines 
> (HNs), so far, I've carried out the following:
> 
> 1. Added a route for the Class D multicast address to the bridge 
> (vzbr0). This enabled multicast from the hosting HN to the VE it was 
> hosting (verified this using ping). However, other nodes, including the 
> VE on the other HN still could not send / receive multicast traffic from 
> the VE.
> 2. Attempted to enable multicast forwarding by echo 1> 
> /proc/sys/net/ipv4/conf/vzbr0/mc_forwarding . However, this was denied 
> ("Operation not permitted"). Perhaps the OpenVZ  RHEL4 kernel does not 
> allow this by default ? However, unsure if this is required to get 
> multicast to work.
> 
> Questions:
> 
> So, no luck with the above. Does anyone have any suggestions as to how I 
> could get this to work ?
> In particular, is enabling the mc_forwarding setting required ? If so, 
> is a RHEL4 kernel available with this enabled ?
> Or is there something else I'm missing ?

I started that forum thread and I got it running. Please print a

route -n

from the hardware node(s) as well as the VEs. Try to use ssmping (RPMs 
for RHEL at http://www.pramberger.at/peter/services/repository/rhel4/) 
for debugging, it helped me a lot.

Regards,

	Peter