实验拓扑： 
R1:Loopback0:1.1.1.1/32 
R2:Loopback0:2.2.2.2/32 
R3:Loopback0:3.3.3.3/32 

配置R1为rp，配置R2为映射代理，把R3加入239.3.3.3组 
方法一：autoRP 
R1: 
ip multicast-routing 
interface Loopback0 
ip pim sparse-mode 
interface Ethernet0/0 
ip pim sparse-mode 
ip pim send-rp-announce Loopback0 scope 5 à 指定R1为候选RP 

R2: 
ip multicast-routing 
interface Loopback0 
ip pim sparse-mode 
interface Ethernet0/0 
ip pim sparse-mode 
interface Ethernet0/1 
ip pim sparse-mode 
ip pim send-rp-discovery Loopback0 scope 5 à将R2指定为映射代理 

R3: 
ip multicast-routing 
interface Loopback0 
ip pim sparse-mode 
ip igmp join-group 239.3.3.3 à 将此接口加入到组239.3.3.3 
interface Ethernet0/1 
ip pim sparse-mode 

注意： 

    • rp-discovery主要是用来响应RP映射（mapping）的

  • ip pim send-rp-announce Loopback0 scope 16 group-list 50 用来设置允许响应的多播地址ACL

  • 若只在sparse模式下要在所有路由器上将224.0.1.39和224.0.1.40加入多播组：ip pim autorp listener，在sparse-dense模式下不需要
方法二：BSR 
R1: 
ip multicast-routing 
interface Loopback0 
ip pim sparse-mode 
interface Ethernet0/0 
ip pim sparse-mode 
ip pim rp-candidate Loopback0 à 指定R1为候选RP 

R2: 
ip multicast-routing 
interface Loopback0 
ip pim sparse-mode 
interface Ethernet0/0 
ip pim sparse-mode 
interface Ethernet0/1 
ip pim sparse-mode 
ip pim bsr-candidate Loopback0 à 将R2配置为C-BSR自举路由器 

R3: 
ip multicast-routing 
interface Loopback0 
ip pim sparse-mode 
ip igmp join-group 239.3.3.3 à 将此接口加入到组239.3.3.3 
interface Ethernet0/1 
ip pim sparse-mode 


另： 
ip pim autorp listener 

這一個指令可能很少人知道，除非你已經準備CCIE Lab一陣時間，不然平時不太會使用到這個功能，好不容易才把它搞懂，這個指令最重要的功能就是可以讓只支援sparse/bidirectional/ssm mode的interface利用dense mode的方式來flooding Auto-RP information，如果題目要求要使用Auto-RP但是不能使用ip pim sparse-dense-mode時，請記得這個指令的存在! 

To cause IP multicast traffic for the two Auto-RP groups 224.0.1.39 and 224.0.1.40 to be Protocol Independent Multicast (PIM) dense mode flooded across interfaces operating in PIM sparse mode, use the ip pim autorp listener command in global configuration mode. To disable this feature, use the no form of this command. 

Usage Guidelines 
Use the ip pim autorp listener command with interfaces configured for PIM sparse mode operation in order to establish a network configuration where Auto-RP operates in PIM dense mode and multicast traffic can operate in sparse mode, bidirectional mode, or source specific multicast (SSM) mode. 

Examples 
The following example enables IP multicast routing and the Auto-RP listener feature on a router. It also configures the router as a Candidate RP for the multicast groups 239.254.2.0 through 239.254.2.255. 

ip multicast-routing 
! 
interface loopback 0 
ip pim sparse-mode 
! 
interface loopback 1 
ip pim sparse-mode 
! 
interface s0/0 
ip pim sparse-mode 
! 
ip pim autorp listener 
ip pim send-rp-announce Loopback0 scope 16 group-list 1 
ip pim send-rp-discovery Loopback1 scope 16 
! 
access-list 1 permit 239.254.2.0 0.0.0.255