RE: some questions about RFC4605 -- IGMP/MLD multicast proxy

Hi Yu-Jung,
 
The downstream of the proxy device is an IGMP/MLD router, and it is not the
router which is interested in multicast groups - it is the IGMP/MLD host.
So, for a proxy device, only the upstream - which is the IGMP/MLD host - can
send MLD reports.
 
Regards,
 
Jayanth
 
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  _____  

From: Yu-Jung Lee [mailto:[email protected]] 
Sent: Friday, February 09, 2007 7:39 PM
To: Jayanth Chennamangalam; [email protected]
Subject: Re: [magma] some questions about RFC4605 -- IGMP/MLD multicast
proxy


Hi, Jayanth:
 
You're right. I see why the proxy device should not forward MLD reports
received from one downtream interface to another downstream interface.
That's because of report suppression. Now my question is, could a proxy
device send out MLD reports on downstream interface if the downstream
interface itself is interested in a multicast group?
 
BR,
Yu-Jung
 

----- Original Message ----- 
From: Jayanth  <mailto:[email protected]> Chennamangalam 
To: [email protected] 
Sent: Friday, February 09, 2007 9:41 PM
Subject: Re: [magma] some questions about RFC4605 -- IGMP/MLD multicast
proxy

Hi Yu-Jung,
 
Consider the following scenarios:
 
1. Querier election is implemented: If the proxy device receives an MLD
Query on a downstream, it should process it for finding out who the querier
should be.
 
---------       ---------
| Proxy |       | Proxy |
---------       ---------
    |               |
    |               |
    -----------------
            |
            |
     Downstream Tree
 
2. Querier election is not implemented: If the proxy device receives an MLD
Query on a downsream, it should not process it, as it should be the only
querier on the network, and no other device should send queries on the
downstream tree.
 
         ---------
         | Proxy |
         ---------
             |
             |
      Downstream Tree
 
In both these cases, MLD Reports received on the downstream should not be
forwared to any other downstream port, as this is not required for any
purpose. Consider the case of an MLD Report from one dowstream interface
(Interface 1) being forwarded on another downstream interface (Interface 2).
Any host on Interface 2 interested in that particular multicast group will
suppress its own MLD Report. So, when the group table is downloaded to the
hardware in the proxy device, it will not have Interface 2 in the forwarding
entry corresponding to that group. This will result in multicast data not
being forwarded to hosts connected to Interface 2.
 
MLD Reports are sent by the proxy device only on the upstream.
 
Regards,
 
Jayanth
 
This email and its attachments contain confidential information from HUAWEI,
which is intended only for the person or entity whose address is listed
above. Any use of the information contained herein in any way (including,
but not limited to, total or partial disclosure, reproduction, or
dissemination) by persons other than the intended recipient(s) is
prohibited. If you receive this e-mail in error, please notify the sender by
phone or email immediately and delete it!

 

  _____  

From: Yu-Jung Lee [mailto:[email protected]] 
Sent: Friday, February 09, 2007 11:02 AM
To: Jayanth Chennamangalam; [email protected]
Subject: Re: [magma] some questions about RFC4605 -- IGMP/MLD multicast
proxy


Hi, Jayanth:
 
Thanks for your response.
Regarding the answer about (3), MLD Reports should not be sent in response
to MLD Queries received on the downstream. I suppose it means that the proxy
device does not forward received MLD reports on downstream interfaces.
However, the proxy does send out unsolicited reports on its downstream
interfaces whenever the interface itself has multicast address of interest,
and also send out solicited reports with group of interest in response to
MLD Queries received on the downstream interface. Is it right?
 
 
BR,
Yu-Jung

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