TCP compatibility: Why is TCP not compatible with packet broadcast and multicasting actions?

Compatible' is a very poor choice of words here. 'Supports' is what is really being described. TCP is a point to point protocol, by design.Period.

TCP multicast is a contradiction in terms.

Compatible' is a very poor choice of words here. 'Supports' is what is really being described. TCP is a point to point protocol, by design.Period.

TCP multicast is a contradiction in terms. EDIT: I updated the Wikipedia page to reflect this comment.

TCP establishes a connection between the sender and the receiver. The sender sends a packet, then waits for acknowledgement from the receiver before sending another1. If a packet goes too long without being acknowledged, it resends the packet until it does receive an acknowledgement (that's how it gets its reliability).

In the case of multicast and broadcast, the sender doesn't even know how many receivers there might be, not to mention who they are. That makes it pretty much impossible for it to wait for confirmation and re-send packets if somebody doesn't acknowledge a packet correctly. 1Technically, there's a "window" that allows it to send, say, five packets before it receives acknowledgement, but you get the idea -- it still needs to know who's receiving, and get acknowledgement of packets that it sent, and re-send packets if they're not acknowledged.

TCP incorporates both flow control and reliability based on acknowledgment from the recipient of the data. A broadcast or multicast transmitter has no idea which or how many other nodes are listening; even if it did by some sort of multipoint synchronization algorithm similar to TCP's point-to-point synchronization, flow control would be an issue because the receiver under the worst conditions would limit the speed of the entire flow.

The short answer is because broadcast TCP is complicated. The long answer is that the important parts of the TCP protocol, namely reliability and congestion control when ported to broadcast semantics are easily subject to abuse, don't scale well, and multicast is simply and optional component of the IPv4 standard and either not implemented or disabled at most core routers. Many papers have been published investigating new protocols to improve scalability; IPv6 promotes multicast to a core protocol requirement and alongside source-specific-multicast significantly improves core routing support and security; leaving the still significant area of abuse.

Abuse covers many aspects of the protocol, from man-in-the-middle attacks, to overloading network infrastructure, causing network storms of traffic upstream to the source. With a Windows machine today you can use the PGM protocol with streams support which operates pretty much as broadcast TCP. It is used by Microsoft's messaging system MSMQ.

msdn.microsoft.com/en-us/library/ms74012...).aspx.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.