Are sockets buffered?

Yes, each socket has its own buffer space where the data payload is stored. Memory to store the buffer is allocated from within the kernel.

Can a single TCP message be sent to multiple destinations at the same time?

Yes. TCP supports a concept call sliding windows. This facility allows for reliable transmission of data using the said protocol. The buffer side depends on the protocol and the side of the sliding window.

How does a TCP socket work?

The TCP protocol is a byte stream service. It does not know anything about the format of the data being sent. It simply takes the data, encapsulates it into a TCP packet, and sends it to the remote peer. The TCP socket then keeps sent packets in memory and waits for an acknowledge from the remote peer.

What happens when TCP buffer is full?

If the receive buffer is empty and the user calls read(2) , the system call will block until data is available. If the receive buffer is full and the other end of the TCP connection tries to send additional data, the kernel will refuse to ACK the packets. This is just regular TCP congestion control.

What is TCP buffer?

Simply put, a TCP Receive Window is a buffer on each side of the TCP connection that temporarily holds incoming data. The data in this buffer is sent to the application, clearing more room for incoming data.

What is TCP send buffer?

The TCP send buffer contains all data sent to the remote host but not yet acknowledged by that host. Each TCP connection will only take system memory when it has data to store in the buffer, but the profile sets a limit called send-buffer-size to cap the memory footprint of any one connection.

Can a port have multiple TCP connections?

Multiple connections on the same server can share the same server-side IP/Port pair as long as they are associated with different client-side IP/Port pairs, and the server would be able to handle as many clients as available system resources allow it to.

How many concurrent TCP connections can a server handle?

On the TCP level the tuple (source ip, source port, destination ip, destination port) must be unique for each simultaneous connection. That means a single client cannot open more than 65535 simultaneous connections to a single server. But a server can (theoretically) serve 65535 simultaneous connections per client.

What is socket messaging?

Sockets and the socket API are used to send messages across a network. They provide a form of inter-process communication (IPC). The network can be a logical, local network to the computer, or one that’s physically connected to an external network, with its own connections to other networks.

How do I know if my socket buffer is full?

You can try ioctl . FIONREAD tells you how many bytes are immediately readable. If this is the same as the buffer size (which you might be able to retrieve and/or set with another icotl call), then the buffer is full.

Why buffering is used in TCP?

Since TCP is a stream-oriented protocol this is what buffers store- a stream of data being sent and received, without any separation into individual packets. Even for the outgoing data, you have no control over how it will be split into packets for transmission over the network.