Example for Configuring PIM-SSM

Owned by Tracy Yang (Unlicensed)
Apr 26, 2023
5 min read


Networking Requirements

PIM-SM is widely used on large-scale networks with sparsely distributed group members. The key mechanisms of PIM-SM include neighbor discovery, DR election, RP discovery, RPT tree building, multicast source registration, SPT switchover and assertion.

The PIM Source-Specific Multicast (PIM-SSM) model provides a solution for source-specific multicast. It maintains the relationship between the host and the router through IGMPv3 and uses part of the PIM-SM mode technology in practical deployment of the PIM-SSM model.

Since the receiver has already known the location of the multicast source in PIM-SSM mode, there is no need for an RP in the SSM model, no need to build an RPT tree, and the multicast source registration process is not required. The PIM-SSM model uses three working mechanisms: PM-SM neighbor discovery, DR election and SPT tree building to implement multicast forwarding tasks in the PIM domain.

In the following topology, a multicast Source sends the multicast traffic to the Receiver through Switch A, Switch B and Switch C.

  • Configure ge-1/1/2 as an IGMPv3 interface on Switch A which connects to the Receiver.
  • In this example, the static route in the RIB will be used by PIM-SSM. 
  • Enable IGMPv3 on the L3 VLAN interfaces of the PIM router connected to the receiver.
  • No need for RP configurations in PIM-SSM.

Figure 1. PIM-SSM Multicast Routing Configuration

Procedure

Switch A

Step1        Configure VLAN.

admin@XorPlus# set vlans vlan-id 2 l3-interface vlan-2
admin@XorPlus# set vlans vlan-id 3 l3-interface vlan-3
admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching native-vlan-id 2
admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching native-vlan-id 3
admin@XorPlus# set l3-interface vlan-interface vlan-2 address 10.10.1.1 prefix-length 24
admin@XorPlus# set l3-interface vlan-interface vlan-3 address 10.10.3.1 prefix-length 24

Step2        Enable IP routing.

admin@Xorplus# set ip routing enable true

Step3       Enable IGMPv3 on the L3 VLAN interfaces of the PIM router connected to the receiver.

admin@XorPlus# set protocols igmp interface vlan-3 version 3

Step4       Enable PIM-SM on the L3 VLAN interfaces.

admin@XorPlus# set protocols pim interface vlan-2 sm
admin@XorPlus# set protocols pim interface vlan-3 sm

Step5       Configure static routes to other switches.

admin@XorPlus#set protocols static route 10.10.2.0/24 next-hop 10.10.1.2
admin@XorPlus#set protocols static route 10.10.4.0/24 next-hop 10.10.1.2

Step6       Commit the configuration.

admin@Xorplus# commit

Step7       Verify the configuration.

  • Run run show pim interface command to show information about all interfaces on which PIM-SM is enabled.
admin@XorPlus# run show pim interface
Interface         State          Address  PIM Nbrs           PIM DR  FHR IfChannels
vlan-2               up        10.10.1.1         0            local    0          0
vlan-3               up        10.10.3.1         0            local    0          0
  • Run run show igmp interface command to show IGMP interface information.
admin@XorPlus# run show igmp interface
Interface         State          Address  V  Querier  Query Timer    Uptime
vlan-2               up        10.10.1.1  3    local     00:00:40  02:13:12
vlan-3             mtrc        10.10.3.1  3    other     --:--:--  00:36:29

Switch B

Step1      Configure VLAN.

admin@XorPlus# set vlans vlan-id 2 l3-interface vlan-2
admin@XorPlus# set vlans vlan-id 3 l3-interface vlan-3
admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching native-vlan-id 2
admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching native-vlan-id 3
admin@XorPlus# set l3-interface vlan-interface vlan-2 address 10.10.1.2 prefix-length 24
admin@XorPlus# set l3-interface vlan-interface vlan-3 address 10.10.2.2 prefix-length 24

Step2        Enable IP routing.

admin@Xorplus# set ip routing enable true

Step3       Enable PIM-SM on the L3 VLAN interfaces.

admin@XorPlus# set protocols pim interface vlan-2 sm
admin@XorPlus# set protocols pim interface vlan-3 sm

Step4      Configure static routes to other switches.

admin@XorPlus#set protocols static route 10.10.3.0/24 next-hop 10.10.1.1
admin@XorPlus#set protocols static route 10.10.4.0/24 next-hop 10.10.2.1

Step5      Commit the configuration.

admin@Xorplus# commit

Step6      Verify the configuration.

  • Run run show pim interface command to show information about all interfaces on which PIM-SM is enabled.
admin@XorPlus# run show pim interface
Interface         State          Address  PIM Nbrs           PIM DR  FHR IfChannels
vlan-2               up        10.10.1.2         0            local    0          0
vlan-3               up        10.10.2.2         0            local    0          0
  • Run run show igmp interface command to show IGMP interface information.
admin@XorPlus# run show igmp interface
Interface         State          Address  V  Querier  Query Timer    Uptime
vlan-2               up        10.10.1.2  2    local     00:00:40  02:13:12
vlan-3             mtrc        10.10.2.2  2    other     --:--:--  00:36:29

Switch C

Step1      Configure VLAN.

admin@XorPlus# set vlans vlan-id 2 l3-interface vlan-2
admin@XorPlus# set vlans vlan-id 3 l3-interface vlan-3
admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching native-vlan-id 2
admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching native-vlan-id 3
admin@XorPlus# set l3-interface vlan-interface vlan-2 address 10.10.2.1 prefix-length 24
admin@XorPlus# set l3-interface vlan-interface vlan-3 address 10.10.4.1 prefix-length 24

Step2        Enable IP routing.

admin@Xorplus# set ip routing enable true

Step3       Enable PIM-SM on the L3 VLAN interfaces.

admin@XorPlus# set protocols pim interface vlan-2 sm
admin@XorPlus# set protocols pim interface vlan-3 sm

Step4      Configure static routes to other switches.

admin@XorPlus#set protocols static route 10.10.1.0/24 next-hop 10.10.2.2
admin@XorPlus#set protocols static route 10.10.3.0/24 next-hop 10.10.2.2

Step5      Commit the configuration.

admin@Xorplus# commit

Step6      Verify the configuration.

  • Run run show pim interface command to show information about all interfaces on which PIM-SM is enabled.
admin@XorPlus# run show pim interface
Interface         State          Address  PIM Nbrs           PIM DR  FHR IfChannels
vlan-2               up        10.10.2.1         0            local    0          0
vlan-3               up        10.10.4.1         0            local    0          0

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