Packet Switching, Layer Models and Protocol Suites... Layered Tasks Computer networks are complex systems software components, and protocols Networking task is divided into several
Trang 1Packet Switching, Layer Models and Protocol Suites
Trang 2 Circuit vs packet switching
Layered tasks
Internet protocol suites
ISO's OSI model
Trang 4Internet Comm - App's
Viewpoint
Two network applications should
interact as if they were directly
connected
But what's going on underneath?
What is inside the "cloud"?
Trang 5Circuit vs Packet Switching
Each stamped with
source and destination
addresses
Routers know where to
forward packets
telephone switch
Router Packet
Trang 6Layered Tasks
Computer networks are complex
systems
software components, and protocols
Networking task is divided into
several subtasks, or layers
Trang 7Real World Example
of two companies
Communicate
Trang 8What Actually Happens
Trang 9Internet Layer Model
The Internet Protocol Stack
Application LayerTransport LayerNetwork LayerData Link LayerPhysical Layer
User
Transmission Medium
Hardware
Software
Trang 10Application Layer
Responsible for providing services to the user
Trang 11Responsible for delivery of a message
from one process to another
Responsible for delivery of a message
from one process to another
Trang 14Network Layer
Network
Layer
Data from Transport
Trang 151.1, 1.2, 6.1, 5.7, are logical addresses
1.1, 1.2, 6.1, 5.7, are logical addresses
R1
R3 R2
Trang 16Data Link Layer
Duties/services
Responsible for transmitting frames
from one node to the next
Responsible for transmitting frames
from one node to the next
Trang 17Data Link Layer
Data Link
Layer
Data from Network
Trang 18Data Link Layer
3B
A3, 3B, 82, 9F, are physical addresses
A3, 3B, 82, 9F, are physical addresses
Trang 19Data Link Layer
Trang 20Responsible for transmitting individual bits
from one node to the next
Responsible for transmitting individual bits
from one node to the next
Trang 22The Big Picture
L5 data H5
L4 data H4 L3 data H3 L2 data
0111011010101001010101001
L5 data H5 L4 data H4 L3 data H3 L2 data
0111010101010010101010101
5 4 3 2 1
5 4 3 2 1
Transmission medium
Trang 23Network D.L
P.L.
D.L P.L.
Network D.L
P.L.
D.L P.L.
sender
router
router
receiver
Trang 24Internet Model
Trang 2528 28
Protocol Suites
A set of protocols must be
constructed
efficient
Each protocol should handle a part of communication not handled by other protocols
How can we guarantee that protocols work well together?
isolation, protocols are designed in
Trang 26Internet Protocol Suite
Trang 27 Two additional layers
Trang 28Responsible for establishing, managing and
terminating connections between applications