TCPIP and OSI

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TCP/IP and OSI
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Internet Connections

• All Internet data is carried in IP packets
• 20 Bytes of header information
• source and destination addresses
• control information for sequencing etc.
• All Internet connections managed by TCP
• TCP allows flow control, error checking and
  retransmission of bad packets
• connection defined by IP address Port number

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TCP provides
Basic Data Transfer - data is delivered Reliabili
ty - errors are corrected Flow Control - slow
receiver is not overloaded by fast
transmitter Multiplexing - many processes at
once - ports Connections - management of
sockets Precedence and Security - urgent and
secure connections
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TCP Header Format
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Sockets

• A socket is an IP addressPort combination
• TCP allows only one connection between 2 uniquely
  identified sockets
• the IP address defines a host computer
• the port number is an operating system handle
  assigned to the connection that allows data input
  and output similar to a file
• sockets originated from the Unix O/S, but are
  implemented in windows by winsock.dll

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Socket States

• Depending on the TCP state, the socket can be in
  various states

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TCP Connection Initiation
HOST 1
HOST 2
Time