PIM Spare-Dense Mode
PIM (Protocol Independent Multicast) is a family of multicast routing protocols. The word independent comes from the fact that PIM does not build a topology of its own, it uses the information from IGP routing protocols to achieve this.
There are a number of different PIM flavors:
· PIM Sparse-Mode
· PIM Dense-Mode
· Bidirectional PIM
· Source-Specific PIM.
PIM (Protocol Independent Multicast) Modes
PIM modes tell how the multicast tree is built from sender to receiver. PIM mode will decide how the tree is built, and who will receive traffic.
PIM supports three different modes:
1. PIM Dense Mode
2. PIM Sparse mode
3. PIM Sparse-Dense mode
PIM Dense mode:- Dense mode forward multicast traffic on all interfaces until a downstream router requests us to stop forwarding.
Pim dense mode Uses implicit join get traffic even if not asked Also called as flood and prune.
PIM Dense Mode Suitable for small multicast implementation. Default hello= 30 sec & dead= 90 sec Discover PIM neighbor (uses 184.108.40.206). Flood all the multicast traffic on all PIM enables interfaces Prune unwanted traffic to Maintain multicast table
PIM Sparse mode:- (PIM-SM) PIM Sparse Mode explicitly builds unidirectional shared trees rooted at an (RP) rendezvous point per group, and optionally creates shortest-path trees per source. (PIM-SM) PIM Sparse Mode generally scales fairly well for wide-area usage.
Sparse-mode protocol does not forward the group traffic to any other router unless it receives a message from that router requesting copies of a packet sent to a particular group.
The PIM spares mode operation begins with the packet being forwarded to a special router called the rendezvous point (RP).
Let's talk about PIM Spare-Dense mode you can use spare mode or dense mode for each multicasting group. But here is the question comes why do we want to use this?
When we use PIM sparse mode, in our multicast routers we need to know where the RP (Rendezvous Point) is in the network and most important which groups they serve. But again we have a solution.
There are two methods:
Static: configure the IP address of the RP on all multicast routers.
Dynamic: use Auto RP or BSR.
When we use PIM Sparse mode and Auto RP, the group-to-RP mapping is sent to the multicast 220.127.116.11 address wait a minute….. How do we receive traffic from 18.104.22.168 when we don’t know where the RP (Rendezvous Point) is? There are two methods to solve this:
Use the IP PIM auto RP listener command.
Use the PIM sparse-dense mode.
The IP PIM auto RP listener command floods auto RP 22.214.171.124 and 126.96.36.199 multicast groups on sparse mode interfaces, allowing all routers to receive the group-to-RP mapping information.
PIM sparse-dense mode also allows us to flood the auto RP 188.8.131.52 and 184.108.40.206 multicast groups but also, it also floods all multicast traffic that we don’t have an RP for.
Let's see the configuration
Let's see the configuration
1. configure the topology as per the diagram
2. configure the IP addresses as per the topology
3. configure OSPF 1 advertise the interfaces
4. configure manually IGMP multicast (220.127.116.11) group membership on router 5 for testing.
5. configure router 3 loopback (192.168.30.1) a static rendezvous point (RP) advertise in OSPF 1 with the mask /24.
6. Make sure route 3 should be RP only for group 18.104.22.168
6. configure RP address on all the routers.
7. configure router 5 to join group 22.214.171.124 and ensure that router 1 should be able to ping the multicast group 126.96.36.199 without RP.
R1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 10.1.1.1 YES manual up up
Serial4/0 188.8.131.52 YES manual up up
Serial4/3 184.108.40.206 YES manual up up
Loopback0 192.168.10.1 YES manual up up
Loopback1 192.168.11.1 YES manual up up
Loopback2 192.168.12.1 YES manual up up
Loopback3 192.168.13.1 YES manual up up