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Unformatted text preview: ed until the message reaches
the Application layer.
10. When the message reaches the
Application layer, the data in the
message is sent to the intended
software recipient. Lecture-3
8. Data Names
The message sent into the
protocol stack at the
Application layer (layer 7) is
called the data or PDU
(protocol data unit).
Once it is encapsulated by
the Presentation layer (layer
6), it is called a protocol data
It retains the label of PDU
until it reaches the Transport 11 The Physical Layer
Accepts the frame from the Data Link
layer and converts the frame into bits
for transmission over the physical
Responsible for receiving bits from the
physical connection medium and
converting them back into a frame to be
used by the Data Link layer.
Contains the device drivers that tell the
protocol how to employ Lthe hardware 12
ecture-3 The Physical Layer …cont.
Through the device drivers and these
standards, the Physical layer controls Throughput rates,
Digital or analog signals or light pulses to
transmit or receive data over the physical
hardware interface. Network hardware devices that
function at layer 1, Lecture-3 Network interface cards (NICs), 13 Data Link Layer
Responsible for formatting the packet
from the Network layer into the proper
format for transmission.
The proper format is determined by the
hardware and the technology of the
network. There are numerous
possibilities, such as Ethernet (IEEE 802.3),
Token Ring (IEEE 802.5),
Asynchronous transfer mode (ATM),
Fiber Distributed Data Interface (FDDI), and
Copper DDI (CDDI). 14 Data Link Layer … cont.
Protocols working at DL Layer
Serial Line Internet Protocol (SLIP)
Point-to-Point Protocol (PPP)
Address Resolution Protocol (ARP)
Reverse Address Resolution Protocol
Layer 2 Forwarding (L2F)
Layer 2 Tunneling Protocol (L2TP)
Point-to-Point Tunneling Protocol
Lecture-3 15 Data Link Layer … cont.
Source and destination addresses to the frame.
The hardware address...
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This note was uploaded on 01/21/2014 for the course IT 205 taught by Professor Kurts during the Winter '08 term at University of Phoenix.
- Winter '08