8.5 组播路由协议

1.组播路由协议作用

1）朝向组播源的接口为上游接口，该接口到达的组播流量才被视为合法，上游接口只有一个。

2）朝向组播接收者的接口称为下游接口，组播路由器负责将流量从下游接口转发出去，下游接口有0至多个。

3）维护组播路由表项，一对二元组（组播源和组播组），在网络中构建一棵无环的树。

2.组播分发树

1）SPT（最短路径树）：树源，组播源为树根，接收者为树叶。

2）RPT（共享树）：以RP（汇聚点）为根，一般为某个性能好的设备。

3.组播表项

1）IGMP组表

[R3]multicast routing-enable 
[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]igmp version 2

[R3]display igmp group 
Interface group report information of VPN-Instance: public net 
 GigabitEthernet0/0/0(192.168.1.254): 
  Total 1 IGMP Group reported
   Group Address   Last Reporter   Uptime      Expires     
   239.1.1.9       192.168.1.1     00:01:02    00:01:23    

2）IGMP路由表

[R3]display igmp routing-table 
Routing table of VPN-Instance: public net 
 Total 1 entry

 00001. (*, 239.1.1.9)
       List of 1 downstream interface 
        GigabitEthernet0/0/0 (192.168.1.254),
                   Protocol: IGMP

3）组播协议路由表

1）R1配置

[R1]interface LoopBack 0
[R1-LoopBack0]ip address 1.1.1.1 32
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]ip address 12.1.1.1 8
[R1-GigabitEthernet0/0/0]pim dm
[R1]interface GigabitEthernet 0/0/01
[R1-GigabitEthernet0/0/1]ip address 13.1.1.1 8
[R1-GigabitEthernet0/0/1]pim dm
[R1]interface GigabitEthernet 0/0/2
[R1-GigabitEthernet0/0/2]ip address 172.16.1.254 24
[R1-GigabitEthernet0/0/2]pim dm
[R1]ospf 1 router-id 1.1.1.1
[R1-ospf-1]area 0
[R1-ospf-1-area-0.0.0.0]network 12.1.1.0 0.255.255.255
[R1-ospf-1-area-0.0.0.0]network 13.1.1.0 0.255.255.255
[R1-ospf-1-area-0.0.0.0]network 172.16.1.0 0.0.0.255

2）R2配置

[R2]interface LoopBack 0
[R2-LoopBack0]ip address 2.2.2.2 32
[R2]interface GigabitEthernet 0/0/0
[R2-GigabitEthernet0/0/0]ip address 12.1.1.2 8
[R2-GigabitEthernet0/0/0]pim dm
[R2]interface GigabitEthernet 0/0/2
[R2-GigabitEthernet0/0/2]ip address 23.1.1.2 8
[R2-GigabitEthernet0/0/2]pim dm
[R2]ospf 1 router-id 2.2.2.2
[R2-ospf-1-area-0.0.0.0]network 12.1.1.0 0.255.255.255
[R2-ospf-1-area-0.0.0.0]network 23.1.1.0 0.255.255.255

3）R3配置

[R3]interface LoopBack 0
[R3-LoopBack0]ip address 3.3.3.3 32
[R3]interface GigabitEthernet 0/0/1
[R3-GigabitEthernet0/0/1]ip address 13.1.1.3 8
[R3-GigabitEthernet0/0/1]pim dm
[R3]interface GigabitEthernet 0/0/2
[R3-GigabitEthernet0/0/2]ip address 23.1.1.3 8
[R3-GigabitEthernet0/0/2]pim dm

[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]ip address 192.168.1.254 24
[R3-GigabitEthernet0/0/0]igmp enable
[R3-GigabitEthernet0/0/0]igmp version 2
[R3]ospf 1 router-id 3.3.3.3
[R3-ospf-1]area 0
[R3-ospf-1-area-0.0.0.0]network 192.168.1.0 0.0.0.255 
[R3-ospf-1-area-0.0.0.0]network 13.1.1.0 0.255.255.255
[R3-ospf-1-area-0.0.0.0]network 23.1.1.0 0.255.255.255 

4）查看组播协议路由表

<R3>display pim routing-table
 VPN-Instance: public net
 Total 1 (*, G) entry; 0 (S, G) entry

 (*, 239.1.1.9)
     Protocol: pim-dm, Flag: WC EXT 
     UpTime: 00:09:56
     Upstream interface: NULL
         Upstream neighbor: NULL
         RPF prime neighbor: NULL
     Downstream interface(s) information: None

5）查看组播路由表

<R3>display multicast routing-table
Multicast routing table of VPN-Instance: public net 
 Total 1 entry
 00001. (172.16.1.1, 239.1.1.9)
       Uptime: 00:02:39
       Upstream Interface: GigabitEthernet0/0/1
       List of 1 downstream interface
           1:  GigabitEthernet0/0/0

6）组播转发表

<R3>display multicast forwarding-table 
Multicast Forwarding Table of VPN-Instance: public net
Total 1 entry, 1 matched

00001. (172.16.1.1, 239.1.1.9)
     MID: 0, Flags: ACT 
     Uptime: 00:03:11, Timeout in: 00:01:41
     Incoming interface: GigabitEthernet0/0/1
     List of 1 outgoing interfaces:
       1: GigabitEthernet0/0/0  
         Activetime: 00:03:11
     Matched 9135395438613 packets(12134871749127996 bytes), Wrong If 17 packets
     Forwarded 9062380994564 packets(12034841960781104 bytes)