In the P2MP process, we put the information such as 1) Spe Address 2) Tunnel ID 3) P2MP ID into the IP v4 & v6 header, so it means we could handle the packets flexiblely.
In most of the subnet technologies, we always put the edge-node as the functional node. I know it is good for 1) easy management 2) less intricacy. But it still has disadvantages: 1) it is not good at scalability 2) the network status is dynamic, even it is a subnet. In the subnet, if we only define the basic operation, that will be fine. But if we want to enlarge the subnet and enrich the functions, so we have limitations. For example, in this P2MP case, if do not define the function at the edge node, but 1) separate the only function node into several ones, 2) put the new function nodes into the MPLS domain, it will be good at 1) Scalability. So we can define the function node at where w!
e want.
2) Save the resource. We can depart the original one packet copy at the nearest fore node,e.g., originally : R1猶E1由2由3猶E2由4, if we R1由2--PE1由3猶E2由4, then we could save the
R2---R5---PE3---R6 R5---PE3---R6
bandwidth at R2. 3) As we could define the function node in the domain, we also could enhance the ability to supervise and enlarge the network functions. I always feel that the subnet core part is fragile. 4) Reduce the workload in the edge node.