PIM Sparse-Dense / Auto-RP

From: ihatecisco@att.net
Date: Sat Feb 28 2004 - 23:34:04 GMT-3

I am just wanting to go over my understanding of Auto-RP, specifically how it
relates to ip pim sparse-dense-mode

When you configure auto-rp. You setup the RP/Mapping agent as

ip multicast-routing
ip pim send-rp-annouce loopback0 scope 255 (no group list)
ip pim send-rp-discovery scope 128

interface lo0
ip address 10.1.1.1 255.255.255.0
ip pim sparse-dense-mode

interface eth0
ip address 192.168.1.1 255.255.255.0
ip pim sparse-dense-mode

-----------------------------------

So in this instance we are sending out the PIM Auto-RP advertisement for the
entire multicast address range.

224.0.0.0/4

128 * 64 * 32 * 16 * 8 * 4 * 2 * 1
----------------------------------------------------------------------------- 

--
 1             1          1          0    |   0       0       0       0

This covers the entire multicast range.

According to the cisco configuration documentation. [very limited and obscure
might i add]  It states that sparse-dense mode will operate as sparse mode for
multicast groups that have RP's defined, and sparse mode for groups that do
not have RPs defined.

Do you have to specificially configure the ip send-rp-announce command with an
access list, or is using the default behavior, [all multicast groups] still
"play nice" with sparse-dense mode?

Any questions or comments welcome.

**Reading the FM**

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