Chapter 1- Intro to Networking

Adjacent-layer interaction

The general topic of how, on one computer, two adjacent layers in a networking architectural model work together, with the lower layer providing services to the higher layer.

De-encapsulation

On a computer that receives data over a network, the process in which the device interprets the lower-layer headers and, when finished with each header, removes the header, revealing the next-higher-layer PDU.

Encapsulation

The placement of data from a higher-layer protocol behind the header (and in some cases, between a header and trailer) of the next-lower-layer protocol.

Frame

A term referring to a data-link header and trailer, plus the data encapsulated between the header and trailer.

Networking model

A generic term referring to any set of protocols and standards collected into a comprehensive grouping that, when followed by the devices in a network, allows all the devices to communicate.

Packet

A logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers and trailers below the network layer.

Same-layer interaction

The communication between two networking devices for the purposes of the functions defined at a particular layer of a networking model, with that communication happening by using a header defined by that layer of the model. The two devices set values in the header, send the header and encapsulated data, with the receiving devices interpreting the header to decide what action to take.

Segment

In TCP, a term used to describe a TCP header and its encapsulated data (also called an L4PDU). Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segments. In Ethernet, a segment is either a single Ethernet cable or a single collision domain (no matter how many cables are used).

Client

Device that accesses a service made available by a server

Server

Device that provides functions/services to a client

Switch

Device that provides connectivity to hosts within the same LAN

Router

Device that provides connectivity between LANs.

Firewall

Monitor/control network traffic based on configuration rules

Network firewall

Hardware devices that filter traffic between networks

Host-based firewall

Software apps filtering traffic entering/exiting a host machine, e.g P.C

Hypertext transfer protocol (HTTP)

To make the request for a web page and return the contents of the web page

Transmission control protocol (TCP)

Error recovery feature- TCP uses the concept of acknowledgements to recover from errors

• The receiver realizes there's a missing TCP segment, they send a segment to the sender requesting for it to be sent again.

• Transport layer protocol

5th layer of TCP/IP model

Application

4th layer of TCP/IP model

Transport

3rd layer of TCP/IP model

Network

• a.k.a "Internet layer"

2nd layer of TCP/IP model

Data-link

1st layer of TCP/IP model

Physical

What 2 functions does the IP protocol address?

1) Addressing- unique IP addresses for each computer

2) Routing- forwarding of packet data to correct destination