PIM

PIM (Protocol Independent Multicast) is a family of multicast routing protocols that enables efficient delivery of multicast traffic by building distribution trees independent of the underlying unicast routing protocol, supporting various operational modes including Dense Mode, Sparse Mode, and Source-Specific Multicast (SSM). It uses Rendezvous Points (RPs) in Sparse Mode to establish shared trees and supports features like Auto-RP and Bootstrap Router (BSR) for dynamic RP discovery and election. PIM provides scalable multicast forwarding for applications such as video streaming, software distribution, and real-time communications while optimizing bandwidth utilization through intelligent tree pruning and grafting mechanisms.

By building multicast distribution trees independent of unicast routing, PIM enables scalable and efficient multicast traffic delivery for diverse applications.

Key Components:

• PIM Mode (mode): Selects the operational mode (Sparse, Dense, Sparse-Dense, SSM).

• Auto-RP (autorp, autorp_listener): Enables dynamic RP discovery and listener functionality.

• Bootstrap Router (BSR) Candidate (bsr_candidate_interface_type, bsr_candidate_interface_id, bsr_candidate_mask, bsr_candidate_priority): Configures BSR candidate interface, mask, and priority.

• Rendezvous Point (RP) Address (rp_address, rp_addresses): Sets static or dynamic RP addresses and group associations.

• Source-Specific Multicast (SSM) Range (ssm_range): Defines the SSM address range.

• RP Candidate (rp_candidates): Configures RP candidate interfaces and group lists.

• VRF-Specific PIM Settings (vrfs): Enables PIM and configures parameters within specific VRF instances.

Key Parameters Briefly Explained:

• mode: PIM operational mode.
• autorp, autorp_listener: Auto-RP settings.
• bsr_candidate_interface_type, bsr_candidate_interface_id, bsr_candidate_mask, bsr_candidate_priority: BSR candidate configuration.
• rp_address, rp_addresses: RP address settings.
• ssm_range: SSM range definition.
• rp_candidates: RP candidate configuration.
• vrfs: VRF-specific PIM settings.

You can use these PIM parameters to control how multicast traffic is routed and managed in your network. Customize the PIM mode, RP discovery mechanisms, and SSM ranges to fit your network’s multicast applications and topology. Adjusting these parameters lets you tailor multicast forwarding for efficient bandwidth utilization and scalable delivery.

The following configuration describes how to set up PIM on a Cisco IOS-XE device, including enabling PIM sparse mode, configuring Auto-RP, BSR candidate, static RP, SSM range, and VRF-specific settings.

ip multicast-routing
!
interface GigabitEthernet0/1
 ip address 10.0.0.1 255.255.255.0
 ip pim sparse-mode
!
interface Loopback0
 ip address 192.168.1.100 255.255.255.255
 ip pim sparse-mode
!
ip pim autorp
ip pim autorp listener
ip pim bsr-candidate Loopback0 30 100
ip pim ssm range 232.0.0.0/8
ip pim rp-address 192.168.1.100 override
ip pim rp-address 10.1.1.1 group-list MULTICAST-GROUPS
ip pim rp-address 10.2.2.2 group-list BIDIR-GROUPS bidir
ip pim rp-candidate Loopback0 group-list 224.0.0.0 interval 60 priority 100
!
ip access-list standard MULTICAST-GROUPS
 permit 239.0.0.0 0.0.0.255
!
ip access-list standard BIDIR-GROUPS
 permit 239.1.0.0 0.0.0.255

The following YAML code defines PIM configuration on an IOS-XE device, including Auto-RP, BSR candidate, SSM range, RP addresses, RP candidates, and VRF-specific settings.

iosxe:
  devices:
    - name: Device1
      configuration:
        pim:
          autorp: true
          autorp_listener: true
          bsr_candidate_interface_type: Loopback
          bsr_candidate_interface_id: "0"
          bsr_candidate_mask: 30
          bsr_candidate_priority: 100
          bsr_candidate_accept_rp_candidate: ACCEPT-RP-ACL
          ssm_range: 232.0.0.0/8
          ssm_default: false
          rp_address: 192.168.1.100
          rp_address_override: true
          rp_address_bidir: false
          rp_addresses:
            - access_list: MULTICAST-GROUPS
              rp_address: 10.1.1.1
              override: false
              bidir: false
            - access_list: BIDIR-GROUPS
              rp_address: 10.2.2.2
              override: true
              bidir: true
          rp_candidates:
            - interface: Loopback0
              group_list: 224.0.0.0
              interval: 60
              priority: 100
              bidir: false
          vrfs:
            - vrf: MULTICAST-VRF
              autorp: true
              ssm_range: 232.0.0.0/8
              rp_address: 172.16.1.1
              rp_addresses:
                - access_list: VRF-GROUPS
                  rp_address: 172.16.2.2