From: ccie2be (ccie2be@nyc.rr.com)
Date: Tue Nov 18 2003 - 05:37:03 GMT-3
There are various ways to secure the mcast domain. Keep in mind what
determines whether a mcast group operates in dense mode or sparse mode when
all interfaces are configured for sparse-dense mode. When a sparse-dense
mode interface receives a mcast packet, what does it do? If the router has
a group-to-RP for that packet, it treats the packet as sparse mode. If
there's no mapping for that group, the router behaves appropriately for
dense mode and floods the packet away from the interface on which it
arrived.
So, working backwards, what determines whether the router has a group-to-RP
mapping for that particular group? If the router received a group-to-RP
mapping from the mapping agent or BSR.
So, then what determines which group-to-RP mappings the mapping agent or BSR
has? That depends on how the RP was configured. If no mcast groups were
excluded when the RP's were configured, then the BSR or mapping agent will
have a mapping for all mcast groups and in this case all routers will have a
group-to-RP mapping for all mcast groups (except the 2 auto-RP groups that
by default operate in dense mode). So, in this case a "sink RP" isn't
needed.
Configuring a "sink RP" is just one way to better secure your mcast domain -
it prevents a rogue RP from becoming active for mcast groups that aren't
explicitly mapped to a valid RP. But, if all mcast groups are mapped to a
valid RP this precaution isn't needed. As I recall, there's also a way to
configure on the mapping agent from which routers (RP's) the mapping agent
will accept group-to-RP mappings. And, there's also a way to prevent rogue
sources from clogging the network.
My point is that there are several ways to better secure your mcast domain.
Which approach you configure in the lab should depend on the lab
requirements. I wouldn't assume any method is needed unless the lab
requirements indicate it is.
----- Original Message -----
From: "Silvio Nunes" <silvio_98@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Monday, November 17, 2003 7:05 PM
Subject: Auto-RP with Multiple RPs Scenario
> Hi all,
>
> Cisco recommends configuring a sink RP on every router in the network, in
> Multiple RPS Scenario with Sparse-Dense-Mode. The sink RP has a
fictitious
> address to prevent reverting to dense mode operation if an RP cannot be
> located.
>
> For LAB, Have I to consider this option if there is multiple RPs ?
>
> Regards,
>
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