Multicast Broadcast

Multicast Broadcast

[berthiaume_wayne]

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	Hello group....

	I have a cluster that I wish to be able to perform a multicast
broadcast over two backbones, primary and secondary, simultaneously. The two
eth's are bound to the same VIP. When I perform the broadcast, it only goes
out on eth0. 
	Is there a way to do this without writing an application to do it?
I've been looking at igmp.c:ip_mc_join_group to do a possible change like:

#ifdef DUAL_MCAST_BIND
   if(!imr->imr_ifindex) {
      imr->ifindex=2;  /* eth0 */
      err=ip_mc_join_group(sk, imr);
      if (!err) {
        imr->ifindex=3; /* eth1 */
        err=ip_mc_join_group(sk, imr);
      }
      return err;
   }
#else
   if(!imr->imr_ifindex)
     in_dev = ip_mc_find_dev(imr);
#endif

	Will this be necessary??? Could there be something in the kerenl to
configure?

PS: Please cc me any response as I'm not yet monitoring this group.

Thanks,
Wayne
EMC Corp
ObjectStorEngineering
4400 Computer Drive
M/S F213
Westboro,  MA    01580

email:       Berthiaume_Wayne@emc.com
                 WBerthiaume@clariion.com

"One man can make a difference, and every man should try."  - JFK







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Re: Multicast Broadcast

[Peter Svensson]

On Wed, 21 Nov 2001 berthiaume_wayne@emc.com wrote:

> 	I have a cluster that I wish to be able to perform a multicast
> broadcast over two backbones, primary and secondary, simultaneously. The two
> eth's are bound to the same VIP. When I perform the broadcast, it only goes
> out on eth0. 

I think you need multicast routing for that to work the way you want it 
to. Flooding multicast traffic between network segments is normally the 
task for multicast routers since you need a routing protocol to prevent 
loops etc. If you send the data on both packets a multicast router 
connected to the two networks would forward a copy each way resulting in 
two packets on both segments.

Peter
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Peter Svensson      ! Pgp key available by finger, fingerprint:
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------------------------------------------------------------------------
Remember, Luke, your source will be with you... always...

Re: Multicast Broadcast

[Jamie Lokier]

berthiaume_wayne@emc.com wrote:
> 	I have a cluster that I wish to be able to perform a multicast
> broadcast over two backbones, primary and secondary, simultaneously. The two
> eth's are bound to the same VIP. When I perform the broadcast, it only goes
> out on eth0. 

I have seen this problem when trying to use an NTP server to multicast
to two ethernets.  Unfortunately, NTP's output would only send to one of
the networks (eth0).

I never did find a workaround.

-- Jamie

RE: Multicast Broadcast

[berthiaume_wayne]

	One potential work-around is a patch to
net/ipv4/igmp.c:ip_mc_join_group.
For example:

#ifdef DUAL_MCAST_BIND
   if(!imr->imr_ifindex) {
      imr->ifindex=2;  /* eth0 */
      err=ip_mc_join_group(sk, imr);
      if (!err) {
        imr->ifindex=3; /* eth1 */
        err=ip_mc_join_group(sk, imr);
      }
      return err;
   }
#else
   if(!imr->imr_ifindex)
     in_dev = ip_mc_find_dev(imr);
#endif

	I'm hoping that there is another way.

Wayne
EMC Corp
ObjectStorEngineering
4400 Computer Drive
M/S F213
Westboro,  MA    01580

email:       Berthiaume_Wayne@emc.com

"One man can make a difference, and every man should try."  - JFK


-----Original Message-----
From: Jamie Lokier [mailto:lk@tantalophile.demon.co.uk]
Sent: Friday, November 23, 2001 3:53 PM
To: berthiaume_wayne@emc.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: Multicast Broadcast


berthiaume_wayne@emc.com wrote:
> 	I have a cluster that I wish to be able to perform a multicast
> broadcast over two backbones, primary and secondary, simultaneously. The
two
> eth's are bound to the same VIP. When I perform the broadcast, it only
goes
> out on eth0. 

I have seen this problem when trying to use an NTP server to multicast
to two ethernets.  Unfortunately, NTP's output would only send to one of
the networks (eth0).

I never did find a workaround.

-- Jamie

Re: Multicast Broadcast

[Andi Kleen]

berthiaume_wayne@emc.com writes:

> 	One potential work-around is a patch to
> net/ipv4/igmp.c:ip_mc_join_group.
> For example:
> 
> #ifdef DUAL_MCAST_BIND
>    if(!imr->imr_ifindex) {
>       imr->ifindex=2;  /* eth0 */
>       err=ip_mc_join_group(sk, imr);
>       if (!err) {
>         imr->ifindex=3; /* eth1 */
>         err=ip_mc_join_group(sk, imr);
>       }
>       return err;
>    }
> #else
>    if(!imr->imr_ifindex)
>      in_dev = ip_mc_find_dev(imr);
> #endif
> 
> 	I'm hoping that there is another way.

It depends on what you want to do, but this "fix" is the same
equivalent to executing IP_ADD_MEMBERSHIP twice with 2 and 3 in the
imr_ifindex field (except that the later doesn't break any programs) 

-Andi

RE: Multicast Broadcast

[berthiaume_wayne]

	Wouldn't the IP address for the two NIC's have to be different for
that to work? I'm binding the same VIP to the two eth's.

-----Original Message-----
From: Andi Kleen [mailto:ak@suse.de]
Sent: Monday, November 26, 2001 11:16 AM
To: berthiaume_wayne@emc.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: Multicast Broadcast


berthiaume_wayne@emc.com writes:

> 	One potential work-around is a patch to
> net/ipv4/igmp.c:ip_mc_join_group.
> For example:
> 
> #ifdef DUAL_MCAST_BIND
>    if(!imr->imr_ifindex) {
>       imr->ifindex=2;  /* eth0 */
>       err=ip_mc_join_group(sk, imr);
>       if (!err) {
>         imr->ifindex=3; /* eth1 */
>         err=ip_mc_join_group(sk, imr);
>       }
>       return err;
>    }
> #else
>    if(!imr->imr_ifindex)
>      in_dev = ip_mc_find_dev(imr);
> #endif
> 
> 	I'm hoping that there is another way.

It depends on what you want to do, but this "fix" is the same
equivalent to executing IP_ADD_MEMBERSHIP twice with 2 and 3 in the
imr_ifindex field (except that the later doesn't break any programs) 

-Andi

Re: Multicast Broadcast

[Andi Kleen]

On Mon, Nov 26, 2001 at 11:33:03AM -0500, berthiaume_wayne@emc.com wrote:
> 	Wouldn't the IP address for the two NIC's have to be different for
> that to work? I'm binding the same VIP to the two eth's.

ifindexes have nothing to do with IP addresses. If you tell the kernel
which interface(s) you want it'll follow your wishes.

There is not really an IP address per NIC; IP addresses are global per host
and the association with an IP interface just defines some defaults which
can be always overwritten by the user if he wants to.

-Andi

RE: Multicast Broadcast

[berthiaume_wayne]

	Andi, forgive my ignorance. I've searched around and can't seem to
find any references to IP_ADD_MEMBERSHIP and how to use it. I did perform an
fgrep() and found the switch in net/ipv4/ip_socketglue.c, but where do I
implement it or how do I call it? Is this something I place in
/etc/sysconfig/network-scriptsifcfg-eth<x> file? Any help would be
appreciated.
Regards,
Wayne
EMC Corp
ObjectStor Engineering
4400 Computer Drive
M/S F213
Westboro,  MA    01580

email:       Berthiaume_Wayne@emc.com

"One man can make a difference, and every man should try."  - JFK


-----Original Message-----
From: Andi Kleen [mailto:ak@suse.de]
Sent: Monday, November 26, 2001 11:16 AM
To: berthiaume_wayne@emc.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: Multicast Broadcast


berthiaume_wayne@emc.com writes:

> 	One potential work-around is a patch to
> net/ipv4/igmp.c:ip_mc_join_group.
> For example:
> 
> #ifdef DUAL_MCAST_BIND
>    if(!imr->imr_ifindex) {
>       imr->ifindex=2;  /* eth0 */
>       err=ip_mc_join_group(sk, imr);
>       if (!err) {
>         imr->ifindex=3; /* eth1 */
>         err=ip_mc_join_group(sk, imr);
>       }
>       return err;
>    }
> #else
>    if(!imr->imr_ifindex)
>      in_dev = ip_mc_find_dev(imr);
> #endif
> 
> 	I'm hoping that there is another way.

It depends on what you want to do, but this "fix" is the same
equivalent to executing IP_ADD_MEMBERSHIP twice with 2 and 3 in the
imr_ifindex field (except that the later doesn't break any programs) 

-Andi

Re: Multicast Broadcast

[Andi Kleen]

On Thu, Nov 29, 2001 at 04:29:22PM -0500, berthiaume_wayne@emc.com wrote:
> 	Andi, forgive my ignorance. I've searched around and can't seem to
> find any references to IP_ADD_MEMBERSHIP and how to use it. I did perform an

man 7 ip

It is a socket option you use in the program that does the multicast
communication.

-Andi

RE: Multicast Broadcast

[berthiaume_wayne]

	Andi, it appears that JVM doesn't support the ip_mreqn struct that
would allow us to use imr_ifindex but supports only the older ip_mreq struct
as the optval. Any other suggestions.
Most appreciated,
Wayne
EMC Corp
ObjectStor Engineering
4400 Computer Drive
M/S F213
Westboro,  MA    01580

email:       Berthiaume_Wayne@emc.com
                 WBerthiaume@clariion.com

"One man can make a difference, and every man should try."  - JFK
 

-----Original Message-----
From: Andi Kleen [mailto:ak@suse.de]
Sent: Thursday, November 29, 2001 4:32 PM
To: berthiaume_wayne@emc.com
Cc: ak@suse.de; linux-kernel@vger.kernel.org
Subject: Re: Multicast Broadcast


On Thu, Nov 29, 2001 at 04:29:22PM -0500, berthiaume_wayne@emc.com wrote:
> 	Andi, forgive my ignorance. I've searched around and can't seem to
> find any references to IP_ADD_MEMBERSHIP and how to use it. I did perform
an

man 7 ip

It is a socket option you use in the program that does the multicast
communication.

-Andi

Re: Multicast Broadcast

[Andi Kleen]

On Fri, Nov 30, 2001 at 04:12:58PM -0500, berthiaume_wayne@emc.com wrote:
> 	Andi, it appears that JVM doesn't support the ip_mreqn struct that
> would allow us to use imr_ifindex but supports only the older ip_mreq struct
> as the optval. Any other suggestions.

ip_mreqn is the only way I can think off. My suggestion is to fix the JVM
or use JNI.


-Andi