GMetrix Networking Unit 2 - Network Infrastructures

Learn about types of networks, which standards certain networks use, and which topologies are being used.

Topologies are…

both physical and logical, and you can have differing topologies in a network

LANs - Local area networks (type of network)

Networks that are generally confined to a single building or even a single area of a building

LANs share…

common resources, such as servers, printers, and to an extent, workstations

DMZ

This is a perimeter network and one type of LAN

Perimeter networks like DMZ…

hold devices that need to be seen by both the public and private security zones of a network

Perimeter networks tend to include…

web servers, email servers, and proxy servers

Back-to-back configuration

When a firewall is on both sides of a perimeter network

Example of possible configuration for perimeter network

Three-leg perimeter configuration: A single firewall with all 3 connections to security zones, each leg is connected to a single firewall

LANs will have…

private IP addresses, which are reserved address ranges for local use

If an IP address starts with 10 (10.0.2.46)…

then it is a private IP address, meaning that it is not routable over a public network, like the internet

Another range of private IP addresses includes…

if an IP address starts with 192.168.__.___

IP addresses that start with the numbers 172.16 through 172.31 is also…

another range of private IP address

You can often see the same IP addresses being used…

on different LANS. This is the whole purpose of private IP addressing. These addresses can be reused, and prevents public IP address from having to be used on every device.

Any IP address starting with 127 is…

a private IP address. 127.0.0.1 between 127.255.255.254 are the private loopback addresses are used to refer to one’s own computer (internal use, not connecting to external networks)

When using the command prompt tool and you ping 127.0.0.1

You can ping your own network card to see if it’s working. A response means that the network card is working, so any network connectivity issues are not a result of a bad network card.

APIPA

Automatic Private IP Addressing. The address range is 169.254.

APIPA is used when…

a device cannot obtain an IP address through a DHCP server, which is a server that gives out IP addresses to devices

If an IP address is in the range 169.254

the device cannot obtain an IP address from a DHCP server, so it can’t connect to any devices except those in the same 169.254 address range.

Floor plan example for VLANs

This is a common situation, in that you need to have multiple physical areas to be on the same network

VLAN (Virtual LAN)

Logical networks that can help connect all of the operations people to each other and all the project management people to each other (if there aren’t that many total users)

Connect the VLANs by…

allocating some of the switch ports to operations and then the rest to project managers. This creates two logical networks in one physical area.

If you want to add more physical switches as needed, use trunk ports between switches…

to logically segment the network

To allow communication between VLANs…

use a router or a switch with router capabilities (known as a multiplayer switch)

When building a local area network, there are 2 main types of LANs

Wired LAN and wireless LAN

Wired LAN

Computers and other devices mainly use Ethernet cables to connect to switches and the switches connect, through Ethernet cables, to one or more routers, which connect a network to other networks, like the internet

Wireless LANs are common to

to homes and small offices

Devices on wireless LANs connect…

to each other or the internet, through a wireless access point, often called a wireless router

Wireless LANs offer more…

flexibility than wired LANs because the devices can connect to the LAN from different places within the building

Wireless LANs tend to be…

slower than wired LANs, a little more susceptible to signal interference, and a little less reliable for consistency in speed and performance

WANs (Wide area networks)

Networks that cover multiple geographic areas and are usually a collection of local area networks (LANs)

An example of a WAN

A company has its corporate headquarters in one location and has satellite offices in multiple locations, each with its own LAN

To connect WAN networks…

leased lines are often used

Leased line

a dedicated connection from one location to another

Dial-up line

These are NOT a type of leased line. While pretty rare, dial-up is still the only means of getting to the outside world for some users.

To use a dial-up connection…

a phone line and a server which accepts dial-up connections is needed

Dial-up connections are…

highly slow by today’s standards

Top advertised speed

56 Kbps (Kilobits per second)

The top speed of a dial-up connection is 

about 38 Kbps

One of the first advancements from dial-up is…

Integrated Services Digital Network (ISDN)

Types of ISDN connections (Integrated Services Digital Network)

BRI and PRI

BRI (Basic Rate Interface)

Uses two 64 Kbps channels for a total speed of 128 Kbps, which is more than double that of a dial-up connection

PRI (Primary Rate Interface)

Uses twenty-three 64 Kbps channels for a total speed of 1.536 Mbps. 

PRI runs on a…

TI circuit line

Many VPN connections use…

Internet Protocol security (IPsec)

IPsec

A suite of protocols that authenticates and encrypts data packets over a VPN connection

IPsec helps to provide…

both confidentiality and integrity of data, which is important for ensuring that data over a VPN connection remains private

3 IPsec protocols

SA, AH, ESP

SA (Security Association)

generates the authentications and encryption keys used in IPsec

AH (Authentication Header)

provides authentication and integrity of data but not data encryption

ESP (Encapsulating Security Protocol)

provides authentication, integrity, and encryption of data

Dedicated lines a customer can obtain for high-speed connections are…

leased lines

T1 Line (type of leased line)

Full T1 line uses twenty-four 64 Kbps channels of data, plus another 8 Kbps for overhead, for a grand total of 1.544 Mbps (not fast by today’s standards)

When someone leases a dedicated leased line…

they have the full, consistent bandwidth of that line

Customers can lease a partial T1 line…

so the customer doesn’t pay for a full T1 line and does not lease the full allotment of 24 channels

T3 Line (type of leased line)

Runs at 44.736 Mbps, equivalent to 28 T1 lines, use 672 64-Kbps channels

Just like with a T1 line

a customer can also lease a partial T3 line and pay less than a full T3 line

The European equivalent of the T1 and T3 lines are…

E1 and E3 lines

The concepts of the E1 and E3 lines are the same as T1 and T3…

but the number of channels each line uses is different, so the line speeds are different

E1 Line (type of leased line)

uses 32 64-Kbps channels, runs at 2.048 Mbps 

E3 line (type of leased line)

Uses 16 E1 lines, runs at 34.368 Mbps, which is slower than a T3 line

For leased lines, the speeds from slowest to fastest are…

T1, E1, E3, T3

Common means of high speed internet connection for both residential and business customers is 

Digital subscriber line (DSL)

DSL (Digital subscriber line)

a customer has a dedicated phone line from the origin to a telco office

For DSL, the closer a customer is to the Telco office…

the faster the connection

If people are not close enough to a Telco office

they cannot get DSL

SDSL (Synchronous DSL)

Upload and download speeds are the same, usually used in businesses that need fast uploads, and more expensive than ADSL

ADSL (Asynchronous DSL)

Most common form of DSL used in homes and businesses

ADSL has different…

upload and download speeds, with download speeds being much higher than upload speeds

Another common means of high-speed connection for a resident of business is…

Cable modem

Cable modem

Uses a cable TV provider for internet connection rather than a phone company for DSL

For using a Cable modem connection, Cable Internet…

tends to run over shared bandwidth, meaning that customers in a concentrated area are sharing the same bandwidth pipeline

For Cable modem, speeds tend to be…

slower during peak usage hours, which is usually early-to-mid-evening, because Cable Internet runs over shared bandwidth

Overall, cable modem speeds tend to be…

faster than that of DSL

DSL connections are on dedicated lines while…

cable modem connections are NOT on dedicated lines

Cellular Network

type of wireless network which most mobile devices run on

Highest speed cellular network is

5G, but this network is not available in every area nor every mobile device at this time

Most mobile devices have access to…

4G or 4G LTE (Long-Term Evolution networks), a faster version of 4G networks

Some mobile devices only have access to…

3G or 2G networks

Remember that on mobile devices, speeds…

vary greatly based on the proximity of a mobile device to a tower

Depending on one’s cellular service plan…

one’s speeds could be hindered during peak hours, or if a cellular customer exceeds a certain amount of used bandwidth per billing period

Satellite Network

Type of internet connection that is prominent in areas to where there is no cable or DSL internet availability and cell service is not consistent

Satellite Internet is generally…

faster than dial-up internet

The biggest issue with satellite networks is that…

latency, the delay from a source to a destination, since a signal needs to travel up to 20,000 miles above the Earth and back down to a destination

Satellite Internet is not optimal for…

real-time activity, like video conferencing and gaming

Wireless networks operate on the…

IEEE 802.11 standard

Wireless networks run on…

the 2.4 GHz frequency or the 5 GHz frequency

Generally 5 GHz are faster, but have shorter range…

and do not carry signals nearly as well as that of the 2.4 GHz frequency signals

The 2.4 GHz and 5 GHz frequencies are NOT…

compatible on the same wireless network (a device with a wireless network card that runs on the 2.4 GHz frequency cannot connect to a wireless router that only runs on the 5 GHz frequency)

Most wireless access points 

run both the 2.4 Ghz and 5GHz frequencies

One standard, the 802.11 standard supports…

both frequencies

802.11a Standard

Frequency: 5 GHz

Speed: 54 Mbps

Indoor Range: 30 meters/100 ft

802.11b Standard

Frequency: 2.4 GHz

Speed: 11 Mbps

Indoor Range: 35 meters/115 ft

802.11g

Frequency: 2.4 GHz

Speed: 54 Mbps

Indoor Range: 38 meters/125 f

802.11n Standard

Frequency: 2.4 GHz or 5 GHz

Speed: 300 Mbps up to 600 Mbps on dual link

Indoor Range: 70 meters/230 ft

802.11ac Standard

Frequency: 5 GHz

Speed: Up to 1300 Mbps

Indoor Range: 27 meters/90 ft

WEP (Wired Equivalent Privacy)

This form of encryption is considered weak, as it has been cracked. Do not use this if you don’t need to.

WPA (Wi-Fi Protected Access)

This is stronger than WEP and possibly the strongest form of encryption available, especially if the wireless access point you are configuring is old

WPA2 (Wi-Fi Protected Access 2)

Currently the strongest form of encryption and this should be used whenever possible. 

Another option for securing wireless networks is to use the 802.11x option

also known as port-based network access control (PNAC).

PNAC can be used…

for both wired and wireless LANs