Subject: [magma] IGMP Snooping on VPLS

From: "Venkatesh Sriram" <[email-masked]>
Date: Wed, 3 Dec 2008 08:50:31 +0530

Hi,

I was reading RFC 4541 and i have a few doubts. I would really
appreciate if somebody could help me clear those.

According to Section 2.1.11 - "A snooping switch should forward IGMP
Membership Reports only to those ports where multicast routers are
attached."

I understand that this would mean that a snooping switch should send
all IGMP Membership Reports that it receives from its customer ports
on to the pseudowire (PW) that connects this switch to the other PE
routers. Is this correct?

According to 2.1.2.  Data Forwarding Rules - " 1) Packets with a
destination IP address outside 224.0.0.X which are not IGMP should be
forwarded according to group-based port membership tables and must
also be forwarded on router ports."

Does this mean that a snooping switch should forward packets with dest
IP outside 224.0.0.X (which are not IGMP) only on the ports over which
it has recvd a prior IGMP report + the PW that conects it to other PE
routers?

Thank You,

Sriram
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From: "Prashant Jhingran (pjhingra)" <[email-masked]>
Date: Thu, 4 Dec 2008 10:50:03 +0530

Yes your understanding seems to be right for both points.

Regards,
Prashant Jhingran
www.cisco.com 
Phone:   +91-80-442 61800
 
-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Venkatesh Sriram
Sent: Wednesday, December 03, 2008 8:51 AM
To: [email-masked]
Subject: [magma] IGMP Snooping on VPLS

Hi,

I understand that this would mean that a snooping switch should send all
IGMP Membership Reports that it receives from its customer ports on to
the pseudowire (PW) that connects this switch to the other PE routers.
Is this correct?

According to 2.1.2.  Data Forwarding Rules - " 1) Packets with a
destination IP address outside 224.0.0.X which are not IGMP should be
forwarded according to group-based port membership tables and must also
be forwarded on router ports."

Thank You,

Sriram

---

From: "Venkatesh Sriram" <[email-masked]>
Date: Thu, 4 Dec 2008 22:08:57 +0530

Hi Prashant,

Thanks for the reply.

Lets assume that i recieve an IGMP Query message from one of my
customer ports. In that case, the snooping switch should also
recognize that port as the router port. Is my understanding correct?

If so, then i should be forwarding all IGMP membership reports on the
PW and this particular customer port.

The same holds true for the second point also.

Is my understand correct here too?

Thanks,
Sriram

---

From: Brian Haberman <[email-masked]>
Date: Sat, 06 Dec 2008 07:24:01 -0500

Hi Sriram,

> recognize that port as the router port. Is my understanding correct?

In general, that is one way to identify a multicast router port. 
However, it is dependent upon the deployment.  If you are supporting 
multiple customers and you don't want to mix their traffic, then simply 
marking ports where queries received as router ports is probably not 
sufficient.

> PW and this particular customer port.

I am not completely up-to-speed on VPLS, but I would think that you 
don't want to blindly forward one customer's Reports to another 
customer's multicast router.

Regards,
Brian