PIM ( Protocol Independent Multicasting) is a protocol used by routers to forward multicast traffic between routers. PIM uses following messages.
1) Hello:
--> In order to send multicast traffic to the other routers, A router need to form neighbor relationship with other routers.
--> Hello messages are used to form neighbor relationship between routers.
--> Every PIM enabled router sends hello message for every 30 seconds
--> Sent by router on multicast destination address 224.0.0.13
2) Prune:
--> Prune Message as name indicates it is used to remove the entry from multicast routing table for a particular group on an router interface.
--> Prune Message is send by downstream router to upstream router to indicate the router to send traffic for multicast group.
--> When a router receives a Prune message it will stops sending multicast traffic for 3 minutes, again after it will flood multicast traffic.
--> To stop this in PIMV2 State Refresh message is used to solve this problem.
3) Graft:
--> Graft message is used to unprune the router interfaces when any new host joins particular multicast group instead of waiting 3 minutes.
4) Prune Override
--> Prune override process is used on multiaccess networks, where if a router receives Prune Message from other routers it will wait for 3 seconds instead of pruning interface immediately. If a router receives join message within 3 seconds it will override prune process.
5) Assert
--> Assert Message is used to select a particular router on multi access networks which is responsible for sending multicast traffic.
--> Whenever routers are connected to multi access network (LAN), they will send Asset Message with following information
i) Administrative Distance
ii) Metric
iii) Interface IP address
The particular router responsible will be selected basedupon following algoritham.
i) Lowest AD
ii) Lowest Metric
iii) Highest IP Address
1) Hello:
--> In order to send multicast traffic to the other routers, A router need to form neighbor relationship with other routers.
--> Hello messages are used to form neighbor relationship between routers.
--> Every PIM enabled router sends hello message for every 30 seconds
--> Sent by router on multicast destination address 224.0.0.13
2) Prune:
--> Prune Message as name indicates it is used to remove the entry from multicast routing table for a particular group on an router interface.
--> Prune Message is send by downstream router to upstream router to indicate the router to send traffic for multicast group.
--> When a router receives a Prune message it will stops sending multicast traffic for 3 minutes, again after it will flood multicast traffic.
--> To stop this in PIMV2 State Refresh message is used to solve this problem.
3) Graft:
--> Graft message is used to unprune the router interfaces when any new host joins particular multicast group instead of waiting 3 minutes.
4) Prune Override
--> Prune override process is used on multiaccess networks, where if a router receives Prune Message from other routers it will wait for 3 seconds instead of pruning interface immediately. If a router receives join message within 3 seconds it will override prune process.
5) Assert
--> Assert Message is used to select a particular router on multi access networks which is responsible for sending multicast traffic.
--> Whenever routers are connected to multi access network (LAN), they will send Asset Message with following information
i) Administrative Distance
ii) Metric
iii) Interface IP address
The particular router responsible will be selected basedupon following algoritham.
i) Lowest AD
ii) Lowest Metric
iii) Highest IP Address
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