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Old 27th August 2012
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jggimi jggimi is offline
More noise than signal
Join Date: May 2008
Location: USA
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Default Chapter 4: Layer 3: Network layer: TCP/IP and its protocols

The "Internet Protocol Suite" consists of more than 130 different protocols. Your /etc/protocols file lists them, by number. Some are very obscure, and some are very commonly used. This introduction takes a look at four of them:

IP, the Internet Protocol (#0)
ICMP, Internet Control Message Protocol (#1)
TCP, the Transmission Control Protocol (#6)
UDP, the User Datagram Protocol (#17)

The network layer model works elegantly here, as TCP/IP's protocols operate in layers. Here is a diagram on TCP/IP from Wikipedia which shows how the a block of information -- a packet -- that uses UDP is transmitted, layer within layer. An Ethernet frame contains an IP packet, which contains a UDP packet, which contains the application data. Each layer is separate, and contains its own control information and the underlying payload for the next layer:

Last edited by jggimi; 28th August 2012 at 08:30 PM.
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