Subject: Re: Is IGMP necessary for permanent memberships in administratively scoped multicast region?

From: [email-masked] (Jeremy Hall)
Date: Tue, 14 Nov 2000 15:32:05 -0500 (EST)

The routers will use IGMP to know who the receivers are. Unless you are
building EVERYTHING from scratch, including your forwarding architecture,
IGMP is required.  The kernel of whatever client machine you are using
will want to set the ethernet card up for the appropriate multicast
groups.

_J

In the new year, Radha Thothadri wrote:
> I am doing some research on a prototype based on administratively scoped
> multicast addresses. The hosts in my model are going to be members of a
> few multicast groups permanently; these multicast groups are assigned
> static administratively scoped multicast addresses and multicast packets
> are restricted to the single network. Under these conditions of
> permanent memberships in multicast groups, do the hosts still need to
> send IGMP messages to report their groups? If IGMP reports have to sent,
> can this be restricted to a one-time report or do the hosts have to
> provide unsolicited reports. Please let me know if IGMP has to be 
> implemented at all under these conditions. 
> Thank you very much.
> Regards,
> Radha Thothadri
>

---

From: Radha Thothadri <[email-masked]>
Date: Tue, 14 Nov 2000 11:15:26 -0600

---

From: "John M. Zwiebel" <[email-masked]>
Date: Tue, 14 Nov 2000 14:48:14 -0800

Radha:

You _might_ consider using:
    [no] ip igmp static-group <group-address> | "*"

This way you would avoid the IGMP host reports.

However, I don't think you will gain much.  It will eliminate the
IGMP host report requirement, but at the expense of other configuration
problems.

I'm interested in discovering how you plan on setting up the 
administrative scope for your data.  If you are using PIM and
plan on using a bootstrap router, be advised that you can not
set up admin scopes for the RP.  It is possible, but difficult,
using auto-rp.  If you actually deploy the admin scopes, you'd be
the first one that I've heard of actually doing it.  (Don't mean
to suggest that there aren't thousands who have, just that I
don't know about it.)

z

 ^ The routers will use IGMP to know who the receivers are. Unless you are
 ^ building EVERYTHING from scratch, including your forwarding architecture,
 ^ IGMP is required.  The kernel of whatever client machine you are using
 ^ will want to set the ethernet card up for the appropriate multicast
 ^ groups.
 ^ 
 ^ _J
 ^ 
 ^ In the new year, Radha Thothadri wrote:
 ^ > I am doing some research on a prototype based on administratively scoped
 ^ > multicast addresses. The hosts in my model are going to be members of a
 ^ > few multicast groups permanently; these multicast groups are assigned
 ^ > static administratively scoped multicast addresses and multicast packets
 ^ > are restricted to the single network. Under these conditions of
 ^ > permanent memberships in multicast groups, do the hosts still need to
 ^ > send IGMP messages to report their groups? If IGMP reports have to sent,
 ^ > can this be restricted to a one-time report or do the hosts have to
 ^ > provide unsolicited reports. Please let me know if IGMP has to be 
 ^ > implemented at all under these conditions. 
 ^ > Thank you very much.
 ^ > Regards,
 ^ > Radha Thothadri
 ^ > 
 ^ 

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	John Zwiebel                       Phone: 408-526-5303
	Cisco Systems Inc.                 
	IP Multicast Group