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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)
      9  TCP/IP Transport Layer Protocols
           9  Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)
                9  TCP/IP Transmission Control Protocol (TCP)
                     9  TCP Fundamentals and General Operation

Previous Topic/Section
TCP Sliding Window Acknowledgment System For Data Transport, Reliability and Flow Control
Previous Page
Pages in Current Topic/Section
1
2
Next Page
TCP Common Applications and Server Port Assignments
Next Topic/Section

TCP Ports, Connections and Connection Identification
(Page 2 of 2)

Multiple Connection Management

This identification of connections using both client and server sockets is what provides the flexibility in allowing multiple connections between devices that we take for granted on the Internet. For example, busy application server processes (such as Web servers) must be able to handle connections from more than one client, or the World Wide Web would be pretty much unusable. Since the connection is identified using the client's socket as well as the server's, this is no problem. At the same time that the Web server maintains the connection mentioned just above, it can easily have another connection to say, port 2,199 at IP address 219.31.0.44. This is represented by the connection identifier:

(41.199.222.3:80, 219.31.0.44:2199).

In fact, we can have multiple connections from the same client to the same server. Each client process will be assigned a different ephemeral port number, so even if they all try to access the same server process (such as the Web server process at 41.199.222.3:80), they will all have a different client socket and represent unique connections. This is what lets you make several simultaneous requests to the same Web site from your computer.

Again, TCP keeps track of each of these connections independently, so each connection is unaware of the others. TCP can handle hundreds or even thousands of simultaneous connections. The only limit is the capacity of the computer running TCP, and the bandwidth of the physical connections to it—the more connections running at once, the more each one has to share limited resources.

Key Concept: Each device can handle simultaneous TCP connections to many different processes on one or more devices. Each connection is identified by the socket numbers of the devices in the connection, called the connection’s endpoints. Each endpoint consists of the device’s IP address and port number, so each connection is identified by the quadruple of client IP address and port number, and server IP address and port number.



Previous Topic/Section
TCP Sliding Window Acknowledgment System For Data Transport, Reliability and Flow Control
Previous Page
Pages in Current Topic/Section
1
2
Next Page
TCP Common Applications and Server Port Assignments
Next Topic/Section

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