multicast?

multicast?

[David Becker]

I trying to use udpcast in Domain 0 without any luck.
I built a xenolinux-2.4.25 with CONFIG_IP_MULTICAST=y
but do not see any multicast packets get in or out.

Anyone know if multicast ought to work?  Or is this a TODO item?

David


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Re: multicast?

[Ian Pratt]

> 
> I trying to use udpcast in Domain 0 without any luck.
> I built a xenolinux-2.4.25 with CONFIG_IP_MULTICAST=y
> but do not see any multicast packets get in or out.
> 
> Anyone know if multicast ought to work?  Or is this a TODO item?

I'm afraid multicast hasn't been a big priority for us. This is
certainly something to bear in mind for the new IO world....

However, there are a couple of hacks that might work.

If you can find out what mcast IP address is being used, you
could try using xc_dom_control to add that address to the domain.

Alternatively, try building the xeno-1.3vnet.bk repository. This
can be (build time) configured to provide L2 switching rather
than L3 routing. I think mcast might 'just work' in this
environment. 

Ian


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RE: multicast?

[Andrew Warfield]

Multicast certainly does not have explicit support within Xen at the moment
-- the current zero-copy code kind of implies single-sender,
single-receiver.  If you are just trying to get a single guest to
participate in a (physically) external multicast group though it should work
fine.  You'll just need to add vfr rules to map the multicast address in to
(and out of) that domain.

Copying packets and allowing multiple-guest delivery is on the list of
things to address in the next iteration of the network code, as it's
something we would like to have for i.e. traffic logging.  This is pretty
unlikely to happen until the I/O subsystem reorganization is complete
though.  

a.

> -----Original Message-----
> From: xen-devel-admin@lists.sourceforge.net [mailto:xen-devel-
> admin@lists.sourceforge.net] On Behalf Of David Becker
> Sent: Thursday, March 11, 2004 11:00 PM
> To: xen-devel@lists.sourceforge.net
> Subject: [Xen-devel] multicast?
> 
> 
> I trying to use udpcast in Domain 0 without any luck.
> I built a xenolinux-2.4.25 with CONFIG_IP_MULTICAST=y
> but do not see any multicast packets get in or out.
> 
> Anyone know if multicast ought to work?  Or is this a TODO item?
> 
> David
> 
> 
> -------------------------------------------------------
> This SF.Net email is sponsored by: IBM Linux Tutorials
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> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel



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Re: multicast?

[David Becker]

" Multicast certainly does not have explicit support within Xen at the moment
" -- the current zero-copy code kind of implies single-sender,

I'm no multicast expert, but from the reading of the sources it looks to
me like multicast sends are no problem, but multicast receives require
that the NIC be told what multicast addresses to pay attention to.
Xen itself appears to have this code: xeno-1.2.bk/xen/net/dev_mcast.c

However the xenolinux network driver doesn't seem to have
the set_multicast_list() function implemented.   I'm guessing this would
need some sort of new hypervisor call? 

Result is domains in xen-1.2 can send to multicast addresses but cannot receive.
Multicast is not critical, just useful, so I'll wait for the brave new
IO world before pursuing it more.


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