Unformatted text preview: and the
same, identical stream of bytes appears at the other end.
Also, TCP does not interpret the contents of the bytes at all. 'TCP has no idea if the data
bytes being exchanged are binary data, ASCII characters, EBCDIC characters, or whatever.
The interpretation of this byte stream is up to the applications on each end of the connection.
This treatment of the byte stream by TCP is similar to the treatment of a file by the Unix operating system.
The Unix kernel does no interpretation whatsoever of the bytes that an application reads or write-that is up
to the applications. There is no distinction to the Unix kernel between a binary file or a file containing lines
of text. 17.3 TCP Header
Recall that TCP data is encapsulated in an IP datagram, as shown in Figure 17.1. file:///D|/Documents%20and%20Settings/bigini/Docum.../homenet2run/tcpip/tcp-ip-illustrated/tcp_tran.htm (2 of 6) [12/09/2001 14.47.10] Chapter 17. TCP: Transmission Control Protocol Figure 17.1 Encapsulation of TCP data in an IP datagram.
Figure 17.2 shows the format of the TCP header. Its normal size is 20 bytes, unless options
are present. Figure 17.2 TCP header.
Each TCP segment contains the source and destination port number to identify the sending
and receiving application. These two values, along with the source and destination IP
addresses in the IP header, uniquely identify each connection.
The combination of an IP address and a port number is sometimes called a socket. This term
appeared in the original TCP specification (RFC 793), and later it also became used as the
name of the Berkeley-derived programming interface (Section 1.15). It is the socket pair
(the 4-tuple consisting of the client IP address, client port number, server IP address, and
server port number) that specifies the two end points that uniquely identifies each TCP
connection in an internet. file:///D|/Documents%20and%20Settings/bigini/Docum.../homenet2run/tcpip/tcp-ip-illustrated/tcp_tran.htm (3 of 6) [12/09/2001 14.47.10] Chapter 17. TCP: Transmission Control Protocol The sequence number...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12