Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
WEEK 1
WHAT IS THE INTERNET
SIMPLE INTERNET DESCRIPTION
Devices on the internet: hosts / end systems
o Connected using communication links and packet switches
Links are physical
o Wires, light, radio
o Has a certain transmission rate in bits/second
One end system sending data to another (1 2)
o End system 1; segments data, add header bytes to each
segment, resulting in packets
o End system 2; reassemble data
Packet switch: receives packet and links it forward
o Routers
o Link-layer switches
Sequence of communication links through a network to reach a
destination is called the route / path through network
ISP: Internet Service Provider
o Network of packet switches and communication links
Protocols: set of rules that governs communication between entities
o End systems, packet switches run on protocols
o Transmission Control Protocol (TCP)
o Internet Protocol (IP)
Internet Standards: Define protocols like HTTP, TCP, IP
o Define Wi-Fi standards
INTERNET PROVIDES SERVICES TO APPLICATIONS
Internet applications
o Include e-mail, web surfing, video streaming, etc.
o Run on end user, not on packet switches
o End systems provide a socket interface to allow programs to communicate over the internet
Socket interface: specifies a set of rules in order to communicate
e.g. rules to send a letter via mail: ZIP, Address, Name, Stamp
Internet has lots of applications
o Developer chooses the application for their service
1|P a g e
, Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
PROTOCOL
A protocol is a set of rules that governs communication between
entities
o Human analogy: Asking for the time involves greetings
o All internet activity is governed by protocols
THE NETWORK EDGE & CORE
NETWORK EDGE
Network hosts
o = end system
o Clients & servers
o Servers can often be found in datacenters
Network core
o Interconnected routers
o High-speed datalinks
Glass-fiber cables
o Network of networks
ACCESS NETWORKS
Network edge consists of access networks
o Residential, institutional, mobile
o A connection (link) is required
Wired or wireless
Types of Access Networks
o DSL (Digital Subscriber Network): DSL is
provided by local telephone company
o Cable: Uses television infrastructure
o Fiber to the Home (FTTH): High speed
connections using optical fiber cables directly
connecting homes
o Ethernet: Most common access technology;
twisted pair of copper wires and ethernet switches
o Wireless LAN: Wi-Fi; uses access points connected to a wired network allowing for wireless access
o Satellite Links: Used in areas where the above are not available
o Dial-Up Access: Based upon traditional phone lines offers slow speeds
2|P a g e
, Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
NETWORK CORE
A mesh of interconnected routers
PACKET SWITCHING
Hosts break down data into packets
o E.g. 10ms of voice data
Forwarded from router to router
o Across links from source to destination
o Transported at full-link capacity
o Routing: determine the route taken by packets
o Forwarding: Move packets from input to appropriate output
Using algorithm
Store-and-Forward Transmission
𝑳
o Takes seconds to transmit L-bits onto a link with rate R
𝑹
o Principle: Entire packet must arrive before it can be further
transmitted
o End-to-End delay: 2 ⋅
QUEUING DELAYS AND PACKET LOSS
Output Buffers: Packet switches have output buffers to store packets waiting for transmission
o Queuing delays occur when packet waits in the buffer
Due to busy output link
Packet Loss: When buffer is full Packet Loss occurs
3|P a g e
, Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
CIRCUIT SWITCHING
Circuit Switching: Entire path (buffers, links transmission rates) are reserved
for the entire communication between end systems
o Enables a constant transmission rate
Traditional telephone networks
o Path is idle when reserved and not used (no sharing)
o Multiplexing
Frequency Division Multiplexing (FDM)
Time Division Multiplexing (TDM)
Packet Switching:
o Resources are not reserved, packets queue and wait in buffers to
access a communication link
o Multiple users on single network
o Packet Loss may occur
Example: 1Mbit/s link
Each user uses 100Kbit/s when active
Users are active 10% of time
Circuit switching: Max 10 users
Packet-Switching: N>>10
Probability of more than 10 users
active at the same time <0.0004
NETWORK OF NETWORKS
A network of networks enables global connectivity and data exchange between end systems, forming the backbone of the
Internet. (Lots of different types are explained in the book, too much work to cover them all)
4|P a g e
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
WEEK 1
WHAT IS THE INTERNET
SIMPLE INTERNET DESCRIPTION
Devices on the internet: hosts / end systems
o Connected using communication links and packet switches
Links are physical
o Wires, light, radio
o Has a certain transmission rate in bits/second
One end system sending data to another (1 2)
o End system 1; segments data, add header bytes to each
segment, resulting in packets
o End system 2; reassemble data
Packet switch: receives packet and links it forward
o Routers
o Link-layer switches
Sequence of communication links through a network to reach a
destination is called the route / path through network
ISP: Internet Service Provider
o Network of packet switches and communication links
Protocols: set of rules that governs communication between entities
o End systems, packet switches run on protocols
o Transmission Control Protocol (TCP)
o Internet Protocol (IP)
Internet Standards: Define protocols like HTTP, TCP, IP
o Define Wi-Fi standards
INTERNET PROVIDES SERVICES TO APPLICATIONS
Internet applications
o Include e-mail, web surfing, video streaming, etc.
o Run on end user, not on packet switches
o End systems provide a socket interface to allow programs to communicate over the internet
Socket interface: specifies a set of rules in order to communicate
e.g. rules to send a letter via mail: ZIP, Address, Name, Stamp
Internet has lots of applications
o Developer chooses the application for their service
1|P a g e
, Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
PROTOCOL
A protocol is a set of rules that governs communication between
entities
o Human analogy: Asking for the time involves greetings
o All internet activity is governed by protocols
THE NETWORK EDGE & CORE
NETWORK EDGE
Network hosts
o = end system
o Clients & servers
o Servers can often be found in datacenters
Network core
o Interconnected routers
o High-speed datalinks
Glass-fiber cables
o Network of networks
ACCESS NETWORKS
Network edge consists of access networks
o Residential, institutional, mobile
o A connection (link) is required
Wired or wireless
Types of Access Networks
o DSL (Digital Subscriber Network): DSL is
provided by local telephone company
o Cable: Uses television infrastructure
o Fiber to the Home (FTTH): High speed
connections using optical fiber cables directly
connecting homes
o Ethernet: Most common access technology;
twisted pair of copper wires and ethernet switches
o Wireless LAN: Wi-Fi; uses access points connected to a wired network allowing for wireless access
o Satellite Links: Used in areas where the above are not available
o Dial-Up Access: Based upon traditional phone lines offers slow speeds
2|P a g e
, Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
NETWORK CORE
A mesh of interconnected routers
PACKET SWITCHING
Hosts break down data into packets
o E.g. 10ms of voice data
Forwarded from router to router
o Across links from source to destination
o Transported at full-link capacity
o Routing: determine the route taken by packets
o Forwarding: Move packets from input to appropriate output
Using algorithm
Store-and-Forward Transmission
𝑳
o Takes seconds to transmit L-bits onto a link with rate R
𝑹
o Principle: Entire packet must arrive before it can be further
transmitted
o End-to-End delay: 2 ⋅
QUEUING DELAYS AND PACKET LOSS
Output Buffers: Packet switches have output buffers to store packets waiting for transmission
o Queuing delays occur when packet waits in the buffer
Due to busy output link
Packet Loss: When buffer is full Packet Loss occurs
3|P a g e
, Summary: Internet Technology – 2023
Book (Computer Networking 7th edition, Kurose & Ross)
Slides: Canvas
Julian Klep
CIRCUIT SWITCHING
Circuit Switching: Entire path (buffers, links transmission rates) are reserved
for the entire communication between end systems
o Enables a constant transmission rate
Traditional telephone networks
o Path is idle when reserved and not used (no sharing)
o Multiplexing
Frequency Division Multiplexing (FDM)
Time Division Multiplexing (TDM)
Packet Switching:
o Resources are not reserved, packets queue and wait in buffers to
access a communication link
o Multiple users on single network
o Packet Loss may occur
Example: 1Mbit/s link
Each user uses 100Kbit/s when active
Users are active 10% of time
Circuit switching: Max 10 users
Packet-Switching: N>>10
Probability of more than 10 users
active at the same time <0.0004
NETWORK OF NETWORKS
A network of networks enables global connectivity and data exchange between end systems, forming the backbone of the
Internet. (Lots of different types are explained in the book, too much work to cover them all)
4|P a g e
