The problem here is that IP multicast packets cannot be delivered via a transport layer protocol like TCP, which provides reliability, simply because the semantics of 1 to 1 communication are much different than those of 1 to N communication. Reliability is, however, very important for several applications, such as financial news dissemination, software distribution, etc. Lack of reliability also makes it difficult to perform accounting and charging. Lack of security and access control. Hosts join IP multicast groups by sending an IGMP join message towards their nearest routers.
Senders have no direct way of controlling or even knowing which hosts have joined the group.
Therefore, access control is very hard and since anyone can join, privacy of the communication is not guaranteed. Furthermore, since any host can send traffic to the group by just addressing packets to the IP multicast address, authentication of the data distributed is also hard. Extensive modifications are needed in IP routers to support IGMP and multicast routing protocols. These problems have delayed the deployment of IP multicast. Vendors addressing IP Multicast's shortcomings Researchers have been working on addressing the reliability problems for several years and many reliable multicast protocols have been proposed.