PIM (Protocol Independent Multicast) is used as router-router signalling protocol for multicast traffic (IGMP used as host-router multicast signalling protocol). In this post we will look at different types of PIM deployment options available.
There are 3 types of PIM deployment variants commonly used in today’s IPv4 multicast deployments.
1. ASM (Any Source Multicast)
RP/Shortest Path Tree -SPT/shared tree
2. SSM (Source Specific Multicast)
Ideal for one to many/No RP/SPT only/IGMPv3
3. BiDir (Bidirectional PIM)
Ideal for many to many/No SPT, shared tree only
In most of the enterprise IPv4 networks, ASM is the popular deployment type that we can see. In this method a Rendezvous Point (RP) needs to configure in order first hop routers of multicast receivers to learn about the multicast sources in their network. In a given network there are 3 ways of configuring RP.
1. Static configuration
‒Manually on every router in the PIM domain
‒ip pim rp-address <address> [group-list <acl>] [override]
‒Originally a Cisco® solution
‒RP-Announcement 126.96.36.199, RP-Discovery 188.8.131.52
3. BSR (Boot Strap Router)
If it is a large enterprise or a service provider (peering with multiple routing domains- inter domain) , two other multicast deployment method used.
1. Multiprotocol BGP (MBGP)
2. Multicast Source Discovery Protocol (MSDP)
To provide resiliency for a RP, it is common to define multiple RPs in a network to avoid single point of failure for multicast services. Further to that there is a feature called “Anycast RP” where you can configure same RP address for multiple routers to give deterministic faster fail-over.
In CCIE wireless exam context, I would assume they would expect a candidate to configure basic PIM (static or auto-rp) & not any other complex configurations or troubleshooting (you could expect all of these in CCIE R&S or SP).
1. Test Yourself- Basic Multicast
2. Configuring Multicast on WLC
3. Wireless Multicast is not working – Why ?
4. Understanding “VideoStream” feature
5. IGMP Basics
6. Multicast Address Allocation
7. PIM-SM Static RP Configurations
8. PIM-SM Auto-RP configurations