CANOGA PERKINS 9171 Configuration Guide - Manual (Page 149)

CanogaOS Configuration Guide
24-7
Source and Group lists of the group.
Forwarding Multicast Packets
PIM-SM routers forward multicast traffic onto all interfaces that lead to receivers that
have explicitly joined a multicast group. Messages are sent to a group address in the
local subnetwork, and have a Time to Live (TTL) of 1. The router performs an RPF check,
and forwards the packet. Traffic that arrives on the correct interface is sent onto all
outgoing interfaces that lead to downstream receivers if the downstream router has sent
a join to this router, or is a member of this group.
24.3.4 PIM-SM Configuration
PIM-SM is a soft-state protocol. The main requirement is to enable PIM-SM on desired
interfaces, and configure the RP information correctly, through static or dynamic
methods. All multicast group states are maintained dynamically as the result of IGMP
Report/Leave and PIM Join/Prune messages. Currently, we supports only one RP for all
multicast groups (224.0.0.0/4).
This section provides PIM-SM configuration examples for two relevant scenarios. The
following graphic displays the network topology used in these examples:
Configuring RP statically
In this example, using the above topology, Router_C is the Rendezvous Point (RP), and
all routers are statically configured with RP information. Host_1 and Host_2 join group
224.0.1.3 for all the sources. They send IGMP membership report to Subnet 1. Two
routers are attached to Subnet 1--Router_E and Router_F; both have default DR priority
on eth-0-1. The Router_E having a higher IP address on the eth-0-1 becomes the
Designated Router (DR), and is responsible for sending Join messages to the RP
(Router_C). While configuring the RP, make sure that:
• Every router includes the ip pim rp-address 10.10.1.5 statement, even if it does
not have any source or group member attached to it.
• There is only one RP address for a group scope in the PIM domain.
• All interfaces running PIM-SM must have sparse-mode enabled. In the
configuration sample below, both eth-0-1 and eth-0-2 are pim sparse-mode
enabled.
Here is a sample configuration at Router_D:
hostname Router_D
!
interface eth-0-0
!
interface eth-0-1
ip pim sparse-mode
!
interface eth-0-2
ip pim sparse-mode
!
ip multicast-routing