Networks
Two or more computers communication together for the purposes of sharing information, along with the necessary infrastructure
Ring Topology
Network components are connected to each other in a closed loop with each device directly connected to two other devices.
Bus Topology
Network components are connected to the same cable, often called "the bus" or "the backbone.
Star Topology
Network components are connected to a central point.
Mixed (or Hybrid) Topology
More than one topology at the same time
Network Protocols
-Agreed-upon formats for exchanging or transmitting data between systems
-Define a number of agreed upon parameters, such as:
-The data compression method
-The type of error checking to use
-Mechanisms for systems to signal when they have finished either
Intranet
A "private" network that is accessible only to authorized users. Many large corporations host an intranet to facilitate information sharing within their organization.
Campus area network (CAN)
A network connecting any number of buildings in an office or university complex (also referred to as a campus wide area network).
Network Topology
How the network is physically or logically arranged.
4 types of IP addresses
(Network & Hosts)
A. N.N.N.H
B. N.N.H.H
C. N.H.H.H
D. Multicast Address
Local Area Network (LAN)
is smaller, in terms of size and geographic coverage and consists of two or more connected devices.
- Home networks and most small office networks can be classified as an LAN.
Wide Area Network (WAN)
tends to be larger, covering more geographic area, and consists of two or more systems in geographically separated areas connected by any of a variety of methods such as leased lines, radio waves, satellite relays, microwaves, or even dial up connections.
Metropolitan area network (MAN)
A network designed for a specific geographic locality such as a town or a city.
Storage Area Network (SAN)
A high-speed network connecting a variety of storage devices such as tape systems, RAID arrays, optical drives, file servers, and others.
Virtual Local Area Network (VLAN)
A logical network allowing systems on different physical networks to interact as if they were connected to same physical network.
Client/Server
A network in which powerful, dedicated systems called servers provide resources to individual workstations or clients.
Topology
how the network is physically or logically arranged.
Protocol
is an agreed- upon format for exchanging or transmitting data between systems.
What defines a number of parameters, such as the data compression method, the type of error checking to use, and mechanisms for systems to signal when they have finished either receiving or transmitting data?
A protocol
12 Types of Network Protocols
- AppleTalk
- Asynchronous Transfer Mode (ATM)
- DECnet
- Ethernet
- Fiber Distributed Data Interface (FDDI)
- Internet Protocols (IP)
- Internetwork Packet Exchange (IPX)
- Signaling System 7 (SS7)
- Systems Network Architecture (SNA)
- Token Ring
- Tran
What is the communications protocol developed by apple to connect Macintosh computers and printers called?
AppleTalk
What protocol is based on transferring data in fixed-size packets so the fixed packet help ensures that no single data type monopolizes the available bandwidth?
Asynchronous Transfer Mode (ATM)
What is the protocol developed by Digital Equipment Corporation that's used to connect PDP and VAX systems?
DECnet
What LAN protocol was developed jointly by Xerox, DEC, and Intel- the most widely implemented LAN standard?
Ethernet
What's the protocol that sends digital data over fiber-optic cabling?
Fiber Distributed Data Interface (FDDI)
What are the protocols for managing and transmitting data between packet-switched computer networks originally developed for the Department of Defense? Most users are familiar with Internet protocols such as email, File Transfer Protocol (FTP), Telnet, an
Internet Protocols (IP)
What was the networking protocol created by Novell for use with Novell NetWare operating systems called?
Internetwork Packet Exchange (IPX)
What is the name of the communications protocol used between private branch exchanges (PBXs) to handle tasks such as call setup, routing, and teardown?
Signaling System 7 (SS7)
What set of network protocols developed by IBM, originally used to connect IBM's mainframe systems?
Systems Network Architecture (SNA)
What are three ways of communication over a network?
- Protocols and History
- OSI networking Model
- Packet Delivery and routing
Internet Protocols (IP)
- Provides addresses used in the internet
- IPv4 and IPv6
The OSI Model
Communications protocols were developed around the Open System Interconnection (OSI) model. The OSI model, is a standard for worldwide communications that defines a framework for implementing protocols and networking components in seven distinct layers.
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Packets
Large chunks of data must typically be broken up into smaller, more manageable chunks (called packets) before they are transmitted from one computer to another.
-More effectively share bandwidth
-Only need to retransmit smaller amount of data if there is
Packet Delivery
Packet delivery can be divided into two sections: local and remote packet delivery.
- Local delivery applies to packets being sent out on a local network
- Remote delivery applies to packets being delivered to a remote system, such as across the Internet
Local Packet Delivery
Each journey though a single network involves a local sender and receiver address, sometimes called a layer 2 or physical address
-With Ethernet, the addresses are called MAC addresses
- To find another system's MAC address, the Address Resolution Protoco
Remote Packet Delivery
- IPv4 addresses are 32-bit numbers that usually are expressed as a group of four numbers (such as 140.1.1.132)
- IPv6 addresses are 128 bits long
- In order to send a packet to a specific system on the other side of the world, you have to know the remote
Routing
The process of moving packets from one network to another is called routing and is critical to the flow of information across the Internet.
- To accomplish this task, routers use forwarding tables to determine where a packet should go.
- When a packet rea
IP Packet
An IP packet has two main sections: the header and the data section (sometimes called the payload).
- The header section contains all of the information needed to describe the packet.
- Some of the things included in the header include:
What kind of packe
ICMP
Used to:
- Determine remote network's availability and the length of time to reach a remote network
- Report to sender errors in transmission back
- During the early development of large networks, it was quickly discovered that there needed to be some mec
Denial-of-Service (DoS) Attacks
- ICMP has been greatly abused by attackers to execute denial-of-service (DoS) attacks
- Because ICMP packets are very small and connectionless, many thousands can be generated by a single system in a very short period of time
- Attackers have developed m
Domain Name System (DNS)
DNS translates names into IP addresses. When you enter the name of your favorite web site into the location bar of your web browser and press ENTER, the computer has to figure out what IP address belongs to that name.
TCP vs. UDP
Transport layer protocols
-TCP = reliable
-UDP = unreliable (best effort)
-Provides process-to-process delivery
- TCP is a "connection-oriented" protocol and offers reliability and guaranteed delivery of packets. UDP is a "connectionless" protocol with no
UDP
Connectionless protocol
- Packets are created and sent on their way
- Unreliable, best effort, no guarantee of delivery
- Data may be submitted to application out of order
- UDP is known as a "connectionless" protocol as it has very few error recovery ser
TCP
Connection-oriented
Reliable, guaranteed delivery
Data will be properly ordered when given to application
Sequence numbers
Three-way handshake:
- TCP is a "connection-oriented" protocol and was specifically designed to provide a reliable connection betwee
Three- Way Handshake
The "guaranteed and reliable" aspect of the TCP protocol makes it very popular for many network applications and services such as HTTP, FTP, and Telnet.
- As part of the connection, TCP requires that systems follow a specific pattern when establishing com
IPv4 Addresses
EX: 192.0.54.87
- 32 bits
- Dotted decimal notation
- Hierarchical
- Network portion
- Host portionNet
Network Classes
- Network address spaces are traditionally divided into one of three classes:
- Class A supports 16,777,214 hosts on each network with a default subnet mask of 255.0.0.0 Subnets: 0.0.0.0 to 126.255.255.255.
- Class B supports 65,534 hosts on each network
IPv4 Masks
-32 bits: ones followed by zeroes
11111111 11111111 11111111 00000000
- Identify network and host portions in address
- One bit in mask means corresponding bit in address is a network bit
- Zero bit in mask means corresponding bit in address is a host bit
What are the steps to determine whether a packet has a local or remote destination?
The steps a host takes to determine whether a packet has a local or remote destination:
1. Bitwise AND the destination address and the mask to determine the network address of the destination network.
2. Bitwise AND host's own address and the mask to dete
How do you configure a Windows Host's IPv4 Address?
On a host: ncpa.cpl to bring up network control panel
Private Addresses
- 10.0.0.0-10.255.255.255 (10.0.0.0/8)
- 172.16.0.0-172.31.255.255 (172.16.0.0/12)
- 192.168.0.0-192.168.255.255 (192.168.0.0/16)
- AKA RFC 1918 Addresses
Network Address Translation (NAT)
- To compensate for this lack of available IP address space, we use Network Address Translation (NAT).
- NAT translates private (nonroutable) IP addresses into public (routable) IP addresses.
IP Addresses and Subnetting
- IP address are 32-bit numbers represented as four groups of 8 bits each (called octets).
- Of those 32 bits in an IP address, some are used for the network portion of the address (the network ID), and some are used for the host portion of the address (t
What are the three types of IPv4 addresses?
Every network has:
- Network address - first address in network (all zeros in host portion)
- Broadcast address - last address in network (all ones in host portion)
- Host addresses - everything in between
Dynamic Host Configuration Protocol (DHCP)
- DHCP server keeps an address pool
Addresses leased
- Can share an address among devices (one device per address at a time)
- Less time consuming and error prone
- DHCP can also give a host additional information, such as its subnet mask and its default
Three Types of IPv4 Destination Addresses
Unicast
- Single destination
- Host portion mixes zeroes and ones
- Sample usage: Most user data
Multicast
- Some, but not all, hosts are intended recipient
- Class D address (First octet between 224 and 239 inclusive)
- Sample usage: Exchange of routing
Subnetting
- Let's look at an example using the IP address 10.10.10.101 with a subnet mask of 255.255.255.0.
- First you must convert the address and subnet mask to their binary
representations:
- Subnet Mask: 11111111.11111111.11111111.00000000
- IP Address: 000010
Port Address Translation (PAT)
- Is an extension to network address translation (NAT) that permits multiple devices on a local area network (LAN) to be mapped to a single public IP address. The goal of PAT is to conserve IP addresses.
Addressing
-A specific identity for your device.