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INTRODUCTION TO NETWORK TOPIC 2.2 - Coggle Diagram
INTRODUCTION TO NETWORK TOPIC 2.2
THE PURPOSE AND FUNCTION OF DATA LINK LAYER
Message Segmentation
Large streams of data are divided into smaller, more manageable pieces to send over the network.
Protocol Data Units
As application data is passed down the protocol stack, information is added at each level. This is known as the encapsulation process.
PDU
◦ Data - application layer PDU
◦ Segment – Transport layer PDU
◦ Packet – Network layer PDU
◦ Frame – Data Link Layer PDU
◦ Bits – Physical Layer PDU
Encapsulation Example
The encapsulation process works from top to bottom:
◦ Data is divided into segments.
◦ The TCP segment is encapsulated in the IP packet
◦ The IP packet is
encapsulated in the Ethernet Frame.
De-encapsulation
. De-encapsulation is the process used by a receiving device to remove one or more of the protocol headers.
Network Addresses
Network layer source and destination addresses - Responsible for delivering the IP packet from the original source to the final destination.
Data Link Addresses
The purpose of the data link address is to deliver the data link frame from one network interface to another network interface on the same network.
Devices on the Same Network
The network layer addresses, or IP addresses, indicate the original source and final destination.
Devices on a Remote Network
Sending to a remote network - the source and destination IP addresses represent hosts on different networks.
Data Link Sublayers
Data link layer is divided into two
sublayers: Logical Link Control (LLC) and Media Access Control (MAC)
Media Access Control
As packets travel from the
source host to the destination host, they travel
over different physical networks.
Data Link Layer Standards
ANSI , IEEE ,ISO ITU
Physical and Logical Topologies
PHYSICAL TOPOLOGY
Refers to the physical connections and
identifies how end devices and
infrastructure devices such as routers,
switches, and wireless access points are
interconnected.
LOGICAL TOPOLOGY
Refers to the way a
network transfers frames from one node
to the next. These logical signal paths are
defined by data link layer protocols.
Common Physical WAN Topologies
POINT TO POINT
HUB AND SPOKE
MESH
Physical LAN Topologies
STAR
BUS
RING
EXTENDED STAR
Half and Full Duplex
Half-Duplex Communication
Both devices can transmit
and receive on the media but cannot do so
simultaneously.
Full-Duplex Communication
Both devices can transmit and
receive on the media at the same time