Re: PIM Sparse-Dense / Auto-RP

From: Bob Sinclair (bsin@cox.net)
Date: Sat Feb 28 2004 - 23:49:38 GMT-3


Auto-RP will work fine without a group-list. For lab purposes, I would
only suggest a group list if it was specified that some groups were not to
use sparse mode.

Auto-RP has required sparse-dense mode because the distribution of RP
information has been distributed by dense mode groups: 224.0.1.39 for
candidate RPs and 224.0.1.40 for mapping agent data.

In other words, before you could distribute regular ip multicast streams
using sparse mode, you had to first distribute auto-rp mappings using dense
mode.

Very recently, the command: ip pim autorp listener was added to make it
possible to distribute the auto-rp mapping information without using dense
mode.

The BSR method does not require dense mode at all, but uses the reserved PIM
address 244.0.0.13 to distribute the mapping info on a neighbor-to-neigbor
basis.

HTH,
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net

----- Original Message -----
From: <ihatecisco@att.net>
To: <ccielab@groupstudy.com>
Sent: Saturday, February 28, 2004 9:34 PM
Subject: PIM Sparse-Dense / Auto-RP

> 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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