Re: SSM, RTCP, SAP

[Gregory Shepherd <shep@juniper.net>]

On Thu, 19 Apr 2001, Mark Handley wrote:

> 
> >At 09:36 PM 4/19/2001 +0100, Tony Ballardie wrote:
> >>Similarly, what about (global) SAP?
> >
> >SAP was developed before the web.  I believe the web makes SAP obsolete, so 
> >we shouldn't worry about supporting it as a special case.
> 
> I don't think SAP is completely obsolete, but I also don't think it's
> very useful for global groups.  SAP is best used for admin-scoped
> multicast groups, where you want the people who can receive the
> session to be the only people who receive the announcement.  The web
> can't easily satisfy this requirement.

http is not only used for globally available content. An enterprise's
intranet could just as easily advertise internal sessions as it does
internal static content.
 
> Admin-scoping doesn't apply for SSM, and I don't think SAP is relevant
> for SSM either. For SSM groups, using RTSP/SDP or HTTP/SDP makes much
> more sense.

True, there is no assigned SSM scoped range, but if/when IGMPv3 is
ubiquitous on the enterprise desktop, then coorporate 'talking head'
sessions could be best served by the mechanisms of SSM BUT in the admin
scoped range. This would only require the network administer to extend the
SSM defined range for the enterprise to include all or a portion of the
admin scoped range. Both JunOS and IOS provide for the default SSM range
(232/8) and any config'd extensions to that range. No SAP required.

Greg

>  - Mark
>