1、PIM Sparse Mode简介
2、实验拓扑
3、基础配置
R1配置
interface Serial0/1
ip address 12.1.1.1 255.255.255.0
interface Serial0/2
ip address 14.1.1.1 255.255.255.0
interface FastEthernet1/0
ip address 13.1.1.1 255.255.255.0
router ospf 110
router-id 1.1.1.1
network 12.1.1.0 0.0.0.255 area 0
network 13.1.1.0 0.0.0.255 area 0
network 14.1.1.0 0.0.0.255 area 0
R2配置
interface Serial0/0
ip address 25.1.1.2 255.255.255.0
interface Serial0/1
ip address 12.1.1.2 255.255.255.0
router ospf 110
router-id 2.2.2.2
network 12.1.1.0 0.0.0.255 area 0
default-information originate always
R3配置
interface FastEthernet1/0
ip address 13.1.1.3 255.255.255.0
router ospf 110
router-id 3.3.3.3
network 13.1.1.0 0.0.0.255 area 0
R4配置
interface Serial0/0
ip address 46.1.1.4 255.255.255.0
interface Serial0/2
ip address 14.1.1.4 255.255.255.0
router ospf 110
router-id 4.4.4.4
network 14.1.1.0 0.0.0.255 area 0
R5配置
interface Serial0/0
ip address 25.1.1.5 255.255.255.0
R6配置
interface Serial0/0
ip address 46.1.1.6 255.255.255.0
no ip routing
ip default-gateway 46.1.1.4
4、配置PIM Sparse Mode
R1配置
ip multicast-routing
interface Serial0/1
ip pim sparse-mode
interface Serial0/2
ip pim sparse-mode
interface FastEthernet1/0
ip pim sparse-mode
R2配置
ip multicast-routing
interface Serial0/0
ip pim sparse-mode
interface Serial0/1
ip pim sparse-mode
R3配置
ip multicast-routing
interface FastEthernet1/0
ip pim sparse-mode
R4配置
ip multicast-routing
interface Serial0/0
ip pim sparse-mode
interface Serial0/2
ip pim sparse-mode
R6配置
interface Serial0/0
ip igmp join-group 224.1.1.1
5、静态选举RP
静态选举RP需要在每台PIM路由器上指定用一个集合点RP，此方法选举出来的集合点RP无备份冗余。
R1配置
interface Loopback0
ip address 1.1.1.1 255.255.255.0
router ospf 110
network 1.1.1.0 0.0.0.255 area 0
ip pim rp-address 1.1.1.1
R2配置
ip pim rp-address 1.1.1.1
R3配置
ip pim rp-address 1.1.1.1
R4配置
ip pim rp-address 1.1.1.1
6、测试
源未发送组播流量前，R1、R4之间形成RPT树，R2、R1之间未形成任何树。
源将多播流量封装到单播中发给集合点RP，由于集合点RP底下有接收者，所以集合点会将源发过来的单播解封将多播流量发给接收者。
随后接收者会向First Hop路由器发送（S，G）Join报文，最终在First Hop路由器和Last Hop路由器间生成SPT树。
7、关闭自动转换SwitchOver
要关闭自动转换SwitchOver只需在Last Hop路由器全局配置模式下配置即可。
ip pim spt-threshold infinity
