Subject: [pim] need some clarification on IGMP Snooping

From: "Anil Kumar" <[email-masked]>
Date: 23 Oct 2005 12:54:07 -0000

Hi,

My topology is as below:

 +------------+       +------------+       +------------+
 |PIM DOMAIN  |       |IGMP        |       |RECEIVER    |
 |            +-------+SNOOPING    +-------+            |
 |            |       |SWITCH      |       |            |
 |            |       |            |       |            |
 +------------+       +------------+       +------------+

Doubt:
------

I can see PIM and OSPF hello packets reaching the receiver.

These control packets are detined to some multicast address. 
The snooping switch is not registered to those multicast address.
Still it is forwarding to the receiver.

Should the snooping switch forward such control packets???

If anybody knows, please clarify my doubt.

Thanks,
Anil.

have a nice day .
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---

From: mark fine <[email-masked]>
Date: Sun, 23 Oct 2005 10:27:32 -0700 (PDT)

from "Considerations for IGMP and MLD Snooping Switches",
draft-ietf-magma-snoop-12.txt:

2.1.2.  Data Forwarding Rules

     2)  Packets with a destination IP (DIP) address in the 224.0.0.X
         range which are not IGMP must be forwarded on all ports.

         This recommendation is based on fact that many host systems do
         not send Join IP multicast addresses in this range before
         sending or listening to IP multicast packets.  Furthermore,
         since the 224.0.0.X address range is defined as link-local (not
         to be routed) it seems unnecessary to keep state for each
         address in this range.  Additionally, some routers operate in
         the 224.0.0.X address range without issuing IGMP Joins, and
         these applications would break if the switch were to prune them
         due to not having seen a Join Group message from the router.

My topology is as below:

Doubt:
------

Thanks,
Anil.

have a nice day .