41902 Lecture Notes - Lecture 1: Packet Switching, Access Network, Communications Protocol
Network Fundamentals:
Overview:
Hardware & software components of a network, end systems and network applications running in
the network, computer network core, switches that transport data, access networks, physical media
that connect end systems, delay, loss, and throughput of data in a computer network, quantitative
model for end-to-end throughput and delay, protocol layering and service models, brief history
Chapter 1: Computer Networks and the Internet
Chapter 1.1: What is the internet?
Internet: etok of etoks
Includes mobile networks, home networks, institution networks, Interconnected ISPs
Internet standards: RFC (Request for comments), IETF (Internet Engineering Task Force)
Protocols: control sending & receiving of messages. E.g. TCP, IP, HTTP, Skype, 802.11
Host/end system: devices such as laptops, tablets, smartphones
End systems are connected by a network of communication links and packet switches.
There are many communication links make up of different physical media e.g. coaxial cable, copper
wire, optical fiber, and radio spectrum.
When one end system has data to send to another end system, data is divided into segments known
as packets. These are sent through the network to the destination end system, where they are
reassembled into their original data.
A packet switch takes an arriving packet from a communication link and forwards the packet
through an outgoing communication link. The most prominent types of packet switches are routers
and link-layer switches. Link-layer switches are typically used in access networks, while routers are
used in the network core. Both forward packets to their destination.
The sequence of communication links and packet switches traversed by a packet from the sending to
receiving end system is known as a route or path through the network.
Protocols define format and order of messages sent and received among network entities, and
define actions taken on message transmission receipt. Network protocol involve machine
communication activity in the Internet.
Chapter 1.2: Network edge
Network edge: Hosts include clients and servers. Servers often located in data centres.
Access networks, physical media: include wired and wireless communication links.
Network core: interconnected routes in a network of networks.
Access Networks:
digital subscriber line (DSL)
• Uses existing telephone
line to central office
DSLAM
cable network
• Frequency division
multiplexing: different
channels transmitted in
diff. frequency bands
Enterprise access networks
(Ethernet)
• Typically used in
companies, universities
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Includes mobile networks, home networks, institution networks, interconnected isps. Internet standards: rfc (request for comments), ietf (internet engineering task force) Host/end system: devices such as laptops, tablets, smartphones. End systems are connected by a network of communication links and packet switches. There are many communication links make up of different physical media e. g. coaxial cable, copper wire, optical fiber, and radio spectrum. When one end system has data to send to another end system, data is divided into segments known as packets. These are sent through the network to the destination end system, where they are reassembled into their original data. A packet switch takes an arriving packet from a communication link and forwards the packet through an outgoing communication link. The most prominent types of packet switches are routers and link-layer switches. Link-layer switches are typically used in access networks, while routers are used in the network core.
