From: Jeff Wishnew (jwishnew@comcast.net)
Date: Fri Sep 05 2003 - 11:31:11 GMT-3
That's not entirely accurate. Sparse-Dense enables the multicast routers to
find the RPs via Auto-RP. The candidate RPs multicast out their intent to
become an RP for particular groups. The Mapping Agents listen for the
announcements and then multicast out the Group-to-RP mappings. All PIM
Sparse-Dense routers will listen for the Mapping Agent's Group-to-RP mapping
announcements.
On the other hand, BSR uses hop-by-hop broadcast to send out the Group-to-RP
mappings. Therefore, you can use strictly Sparse mode when using BSR.
Jeff Wishnew
CCIE #12148
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: "Group Study" <ccielab@groupstudy.com>; "Roger McNeace"
<rmcneace@terremark.com>
Sent: Friday, September 05, 2003 9:26 AM
Subject: Re: PIM-Sparse vs Sparse-Dense
> The sparse-dense mode, as I understand it, is so that all the multicast
> routers find out who the RP's are automatically via either Auto-RP or BSR.
> If the routers are only sparse mode, then you have to manually configure
the
> address(es) of the RP's on each router.
>
> For further info, see either Beau Williamson book, Developing IP Multicast
> Networks, Chapter 12 or Dolye's Routing TCP/IP volume II.
>
> HTH, dt
>
> ----- Original Message -----
> From: "Roger McNeace" <rmcneace@terremark.com>
> To: <ccielab@groupstudy.com>
> Sent: Friday, September 05, 2003 9:27 AM
> Subject: PIM-Sparse vs Sparse-Dense
>
>
> > As I understand it by default on Cisco routers PIM-Sparse mode will
> > automatically switchover to a SPT (dense mode) to a source since the
> > threshold is set to 0. Why and when would I need Sparse-Dense if Sparse
> > alone does the same thing?
> >
> >
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