comptia network+ notes
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CompTIA Network+ (N10-005)
LAN / WAN
LAN (Local Area Network)
data network restricted to a single geographic location
encompasses a relatively small area
(examples) office, building, school, etc.
WAN (Wide Area Network)
spans more than one geographic location location
connects separate LANs
MAN (Metropolitan Area Network)
WAN that is confined to a certain geographic area
(example) university campus, city, etc.
Network Models
Peer-to-Peer
decentralized network model
no centralized storage of data or control over the sharing of files or
resources
each computer serves as its own client and server
no admin is needed
no more than 10 computers should be connected
Client / Server
centralized model
services are managed from a central location
user management
security
backup procedures
size is only limited by server size
The role of the client computer is to request the data from the server
Centralized Computing model
one system provides both the data storage + processing power for client
systems
Distributed Computing model
processing power distributed between client systems and server
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Wired Network Topologies
Topology
physical topology - networks physical layout of computer cables/devices
logical topology - the way in which the network appears to the devices thatuse it
Bus
all computers are connected to a single cable serving as the backbone
T Connectors- used for systems to connect to backbone
each end of the bus must be terminated
if not, it disrupts data transmissions
one end also must be grounded
a hub or switch is not needed
Ring
it is logical
data travels in a circular fashion
hub or switch is not needed
if single system on ring fails, whole network fails
when computers are added or removed from network, disruption occurs
MSAU (Multi Access Unit) - performs the token circulation
Star
all computers connect to a central device (hub or switch)
each connected device requires a single cable to be connected
creates a point-to-point (PtP) connection
easiest to expand and add devices
most popular
Mesh
each computer on network connects to every other computer
point-to-point (PtP) with each computer
provides high level of redundancy
better fault tolerance
to calculate number of connections in a mesh
y(y-1)/2 y = # of computers | 5 computers = 10 connections
Hybrid
combines different kinds of topologies
PtP (Point-to-Point)
2 computers connected directly to each other
no need for a central device
can be created using a crossover cable
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(example) computer connected to printer
PtMP (Point-to-MultiPoint)
looks like a star network, but without a central connection
has a single system acting as common source through which all
members are connected
had device that provides a path to any or all connected devices
MPLS (Multiprotocol Label Switching)
technology designed to speed up traffic flow
creates a channel/path for packets to reach destination
each packet is assigned a label
the label associates it with the specific path
all packets with the same label use the same path
known as LSP (Label Switched Path)
eliminates need to check the packet for forwarding at each hop
reduces need to check routing tables
Wireless Network Topologies
Infrastructure
used to extend a wired LAN to included wireless devices
wireless devices communicate with the wired LAN through the WAP
commonly used to extend a wired LAN to include wireless devices
WAP forms a bridge between a wireless and wired LAN
WAP must stay connected to the wired network
there can be several wap to cover a large area, or a single wap for smaller
areas
Ad Hoc
devices communicate directly between themselves without using an
access point
connect a small number of computers
does not use an AP
Virtual Networks
VPN (Virtual Private Network) a secure communication channel across the public network, enabling
access for a client to a private network
such as a company's internal network
provides point-to-point dedicated link between two points over a public IP
network.
establishes connection between remote clients and a private network
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Components of VPN Connection
VPN client - computer that initiates the connection
VPN server - authenticates connections
Access method - public network, sometimes a private intranet
VPN protocols
PPTP (Point-to-Point Tunneling Protocol) L2TP (Layer 2 Tunneling Protocol)
enables authentication and encryption to protect data from
general public
LAN-to-LAN
when a VPN is used to connect one private LAN to another
VLAN (Virtual Local Area Network)
used for network segmentation
Logical group of workstations
segmentation is used for several reasons
security, organization, performance a group of connected computers that act as if they are on their own
network segments
VLan Membership
Protocol-based = assigned by their protocol in use and the Layer 3
Port-based = the ports of the switch are configured to belong to the
various VLAns
MAC address-based = assigns membership according to the
workstations MAC address
Subnet-based = the subnets of the IP addresses of individual
computers are used to identify the VLAN to which it belongs
{ OSI +TCP/IP Models + Network Protocols }
OSI Layers
(Open System Interconnection)
Describes a network architecture that enables data to be passed between
computer systems
Layer 1 - Physical Layer
Layer 1 Devices = NIC, Hub, Repeater, network cabling
Defines the physical structure of the network and the topology
Hardware
type of cable, connector, pinout format for cables
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Topology
ring, mesh, star, bus
defines voltage, frequency of signals, speed and bandwidth, maximum
distance, multiplexing strategy
Common problems = NIC failure or not properly seated, faulty hub or
repeater, cut or damaged network cable bits - the logical grouping of data at the Physical Layer
Layer 2 - Data Link Layer
Layer 2 Devices: Bridge, Switch, NIC, AP
Receives and puts data on the cable
Provides error detection and correction
Two sublayers: MAC and LLC
responsible for getting data to Layer 1 (Physical Layer)
getting data on or off the cable responsible for error detection, error correction and hardware addressing
When sending data: groups bits into packets for transmission over
network
When receiving data: takes packaged data and breaks it into individual bits
for Layer 3
MAC Layer
(Media Access Control Layer)
MAC address is defined at this layer
(example) 00:A0:C9:14:C8:29 First half of MAC address is ID number of the NIC
manufacturer
Second half is the unique number assigned to the NIC by
the manufacturer
LLC Layer
(Logical Link Control Layer)
responsible for flow-control
Will make sure not too much data is being sent waiting
period for data is not too long data that was damaged gats
re-sent
CRC (Cyclic Redundancy Check)
provides error detection by using a calculated value
is a value that is added to the packet by the LLC on the
sending end
its recalculated on the receiving end and compared to the
original if matches, data is ok
frames / packets- the logical grouping of data at the Data Link Layer
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Layer 3 - Network Layer
Layer 3 Devices: Switch, Router
Handles the discovery of destination systems and addressing
Manages network addresses
when Receiving Data
reads data packets that are passed from Layer 2
Checks packets for destination address
Compares destination address to its own IP address to determine
if the packet should be passed up to Layer 4
when Sending Data
receives data from layer 4
adds its own IP address to the packet as the source address
protocols at Layer 3 are responsible for route selection Datagrams / Packets - the logical grouping of data at the Network Layer
Layer 4 - Transport Layer
Provides connection services between sending and receiving devices
Ensures reliable data delivery
correct sequence, without errors, fastest and most efficient flow
rate possible
Manages flow control through buffering or windowing
Provides segmentation, error checking, and service identification
Segmentation - blocks of data need to be broken into packets ofmanageable sized for the lower layers (and opposite for upper layers)
data is transferred over network in two ways:
UDP - connectionless
excellent for data that must be delivered asap
(examples) video, walki-talkie radio, etc.
no confirmation
TCP - connection-oriented
connection is established before communication begins
data is delivered in sections
confirmation system is used to make sure the data was
delivered
Data flow control
Buffering - data is temporarily stored and waits for the destination
device to become available
Windowing - data is sent in groups of segments
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Layer 5 - Session Layer
Synchronizes the data exchange between applications on separate
devices
Layer 6 - Presentation Layer Serves as translator between Layer 7 and Layer 5
Translates data from the formated used by applications into one that can
be transmitted across the network
Formats data from Layer 7 into format that can be sent over network
Handles encryption and decryption of data
encryption - scrambling of data so that it cant be read by anyone
other than the intended recipient
Provides compression and decompression functionality
Layer 7 - Application Layer Provides access to the network for applications
Take requests and data from the users and pass them to the lower layers
of the OSI model
provides full end-user access to network services
this is where bits (0s and1s), MAC and IP addresses are translated so ppl
can understand it
TCP/IP Model
TCP/IP Model OSI Model
4. Application Layer 7. Application Layer
6. Presentation Layer
5. Session Layer
3. Transport Layer 4. Transport Layer
2. Internet Layer 3. Network Layer
1. Network Interface
Layer
2. Data Link Layer
1. Physical Layer
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Protocol Ports
Protocol Port
FTP 20,21
SSH 22
Telnet 23
SMTP 25
DNS 53
DHCP (BOOTP server) 67
DHCP (BOOTP client) 68
TFTP 69
HTTP 80
POP3 110
NNTP 119
NTP 123
IMAP4 143
SNMP 161
HTTPS 443
RDP 3389
Protocols
IP (Internet Protocol)
connectionless responsible for addressing and routing of packets between computers
used to move data around a network
Layer 3 - Network Layer
TCP (Transmission Control Protocol)
Layer 4
connection-oriented
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responsible for guaranteed delivery of data
offers flow control, sequencing, retransmission of dropped packets
TCP three-way handshake
1. sends message called a SYN to the target host
2. host sends back acknowledgement, ACK
3. responds to the acknowledgement with another ACK breaks data into manageable packets
tracks info such as source & destination of packets
able to reroute packets
UDP (User Datagram Protocol)
connectionless
Layer 4 - Transport Layer
DHCP (Dynamic Host Control Protocol)
Gives out IP addresses
FTP (File Transfer Protocol)
used for transferring files between two remote systems uploads and downloads files to and from remote host
basic file-management tasks
Layer 7 - Application Layer
port 21 is mostly used in modern implementations, not 20
SFTP (Secure File Transfer Protocol)
securely uploads and downloads files to and from remote host
based on SSH security
Layer 7 - Application Layer
TFTP (Trivial File Transfer Protocol)
connectionless Layer 7 - Application Layer
SMTP (Simple Mail Transfer Protocol)
HTTP (Hypertext Transfer Protocol)
retrieves files from a web server
Layer 7 - Application Layer
HTTPS (Hypertext Transfer Protocol Secure)
secure protocol for retrieving files from a web server
Layer 7 - Application Layer
POP3 / IMAP4
retrieves mail
cannot send mail
Layer 7 - Application Layer
Telnet
enables sessions to be opened on a remote host
Layer 7
SSH (Secure Shell)
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port: 22
enables secure sessions to be opened on remote host
or secure alternative to Telnet
Layer 7
ICMP (Internet Control Message Protocol)
used for error reporting, flow control, route testing Layer 3
ARP (Address Resolution Protocol)
resolves IP addresses to MAC addresses to enable communication
between devices
Layer 2
RARP (Reverse Address Resolution Protocol)
resolves MAC addresses to IP addresses
NTP (Network Time Protocol)
communicates time synchronization information between devices
Layer 8 NNTP (Network News Transport Protocol)
SCP (Secure Copy Protocol)
LDAP (Lightweight Directory Access Protocol)
Accesses and queries directory services systems
Layer 7
IGMP (Internet Group Management Protocol)
TLS (Transport Layer Security)
SIP (Session Initiated Protocol)
RTP (Real-time Transport Protocol)
for transporting real-time data often used with VoIP
Layer 7
DNS (Domain Name Service)
resolves hostnames to IP addresses
before DNS the Internet used to use a text file called HOSTS to perform name
resolution
DNS Clients
AKA resolvers
systems that ask DNS servers for a hostname-to-IP address mapping
DDNS (Dynamic DNS)
newer system that enables hosts to be dynamically registered with the
DNS server
DNS namespace
space that has logical divisions hierarchically organized
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.com .edu .uk .de
FQDN (Fully Qualified Domain Name)
domain name along with subdomains
(example) www.comptia.org
www = host
comptia = second-level domain .org = top-level domain
reverse lookup
IP address-to-hostname
accomplished by using Pointer Records (PTR)
DNS Records
MX (Mail Exchange)
stores info about where mail for the domain should be delivered
AAAA (IPv6)
Stores info for IPv6 addresses it is commonly used to map hostnames to an IP address for a host
CNAME (Canonical Name)
stores additional hostnames, or aliases, for hosts in domain
give single computer multiple names (aliases)
PTR (Pointer)
used to perform a reverse DNS lookup
name is returned when query originates with an IP address
SOA (Start of Authority)
record of info containing data on DNS zones and other DNS
records WINS (Windows Internet Name Services)
can be used to resolve NetBIOS names to IP addresses
SNMP
(Simple Network Management Protocol)
protocol that makes NMS possible
NMS = Network Management System
used for monitoring information on a network
performed through a software component called an agent
monitor any device that is SNMP capable
computers, printers, routers, servers, etc.
MIB
databases of info to define what parameters are accessible, read-only and
can be set
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Communities - logical groupings of systems. If device is part of a community tit
communicates only with other devices within it
traps - captures snapshot data of the system
could be system errors, resource info etc.
SNMPv2
enhancements on v1 includes bit strings, network addresses and counters
SNMPv3
better security: authentication + encryption
DHCP
scopes - ranges of IP addresses
lease - address that is assigned for a predetermined amount of time
reservation - when a specific address assigned to a client. IP always remains the
same.
exclusion - certain IP addresses that are not to be given out
DHCP is protocol-dependent, not platform-dependent.
Can provide DNS suffixes to clients
DNS Suffixes - define DNS servers to be used and the order in which to
use them
Process
1. Client broadcasts dhcpdiscover packet
2. DHCP picks up the packet, compares request with scopes it has
defined
3. DHCP sends address + lease duration through dhcpofferpacket
4. Client receives offer, determines if it is suitable
5. Client sends back dhcprequestpacket
6. DHCP finalizes and sends dhcpack packet of acknowledgement
{ Addressing + Routing }
IP Addressing
IP Address - defines the number of the network and the number of the node
Subnet Mask - defines which portion of the IP address refers to the network
address and which refers to the node address
Default Gateway - path out of the network for a given device
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if system is not configured with any static routes or a default gateway, it is
limited to operating on its own network segment
Subnetting = increased number of network IDs decreases number of node IDs
Unicast = single address is specified. Data is delivered to a specific node.
Broadcast = message goes to everyone on the network
Multicast = a single source sends data to multiple destination addresses CIDR (Classless Interdomain Routing)
method to assign addresses outside the standard ABC classes
BOOTP = used to obtain info needed to connect to the network
System that does not support APIPA will assign itself an IP address of 0.0.0.0.
IPv4 IPv6
Loopback Address 127.0.0.1 ::1
Network-wide addresses Public IP ranges
Class A: 1.0.0.0 - 126.255.255.255
Class B: 128.0.0.0- 191.255.255.255
Class C: 192.0.0.0 - 223.255.255.255
Global Unicast Addresses
Private network addresses Class A: 10.0.0.0 - 10.255.255.255
Class B: 172.16.0.0 - 172.31.255.255
Class C: 192.168.0.0 - 192.168.255.255
Site-local Address ranges
FEC0::
Autoconfigured addresses APIPA: 169.254.0.1 - 169.255.254.0 Link-local Addresses
FE80::
NAT (Network Address Translation)
Enables a LAN to use a different set of IP addresses for internal traffic and
another for external
computers can hide behind a single IP address
one registered IP address acts as the gateway between the internal and external
networks
to the remote host, the request looks like it is originating from a single address
system performing NAT function keeps track of who asked for what and makes
sure data is returned PAT (Port Address Translation)
a service of NAT
SNAT (Static NAT)
maps a private IP to a static unchanging public IP address
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Routing
Default Gateway
is the routers IP address
help forward the packet to its destination network
provides route for destinations outside the local network gateway can be a device, system or application that translates data from
one format into another
Routing Table
Destination = the host IP address
Network Mask = the subnet mask value for the destination
Gateway = Where the IP address is sent
Interface = address of interface used to send the packet of destination
Metric = measurement of directness of a route, the lower the metric the
faster the route
Hop Counts - number of hops necessary to reach node. if it counts
to infinity it means route is unreachable.
MTU (Maximum Transmission Unit) - defines largest data unit that
can be passed without fragmenting
Bandwidth - maximum packet size permitted for transmission
Costs - the lower the cost, the more that route should be favored
Latency - amount of time it takes for packet to travel from one
location to another
routers get info for the routing table in two ways: static routing & dynamic routing
Static Routing is manually entered into the routing table
route add= command used to add a static route to the routing table
route add -p = makes the static route persistent
Dynamic Routing
routers pass info about themselves to other routers so that they can build routing
tables
uses 2 protocols: Distance-Vector Routing & link-state
Distance-Vector Routing
each router on network communicates all the routes it knows about to the
routers to which it is directly attached
RIP
limited to a max of 15 hops
requires updates every 30 seconds
no authentication
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RIPv2
authentication
limit 15 hops
BGP
pick best available route
EIGRP uses neighbors to help determine routing table
keeps copy of their routing info
find best possible route
using DAUL (Diffusing Update Algorithm)
Convergence - time for the routers to detect and accommodate a change
Routing Loops - occur when routing tables on the routes are slow to
update
Split Horizon - to prevent routing loops
Poison Reverse - to prevent routing loops
Next Hop- the next closest router that a packet can go through
Link-State Routing
build a map of entire network and then holds the map in memory
updates occur less frequently
OSPF (Open Shortest Path First)
least-cost path
used in medium to large enterprise networks
IS-IS
discovers shortest path for data to travel using Shortest Path First
algorithm (SPF) in large ISP networks
STP (Spanning Tree Protocol)
Actively monitors the network and shuts down redundant links to prevent
switching loops
Switching loops - caused by having more than one path between two switches in
a network
STP prevents this
STA is the algorithm STP uses to correct loops
BPDU (Bridge Protocol Data Unit)
used to identify the status of ports and bridges across the network
redundant paths and loops can be avoided with ports by:
blocking | disabled | forwarding | learning | listening
Trunking
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trunking is the use of multiple network cables
Link Aggregation is another name for it
the process of transferring VLAN traffic between multiple switches
to connect the two (or more) switches together
configure a port on each switch as a trunk port
connect two switches via trunk ports IEEE 802.1Q is the trunk standard that now allows you to connect switches from
different manufacturers
Port Mirroring
monitors network traffic
enables administrators to monitor the traffic outbound and inbound to the switch
{ Components + Devices }
Bridges
Connects LANs to reduce overall network traffic
enables data to pass through it or prevent data from passing through it
done by reading MAC address
divide larger networks into smaller sections
sits between 2 physical network segments and manges flow of data
between them
can elect to forward the data or block it from crossing can connect two physical LANS into a larger logicalLAN
learning bridges - can build a list of MAC address
Bridge Placement
80% of data should be local
20% should be for other side of bridge
Bridge Loops
when more than one bridge is implemented on network
Spanning Tree Protocol assigns value to bridge to be used to control
bridge-learning process
Transparent Bridge
devices on network dont see it
used to segment a network
reduces number of collisions and traffic
blocs or forwards data based on the MAC address
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Source Route Bridge
used in token ring networks
Translational Bridge
converts one networking data format to another
NIC
Link Light - indicates whether a network connection exists
Activity Light - indicates activity, should flicker
Switches
Cut-through - packet just gets forwarded, no error check
store-and-forward - error checked before forwarded
Fragment Free - faster at forwarding + checking
CSU/DSU
translates digital signals used on a LAN into those used in WAN
Modems
modulate/demodulate
translates signals from analog to digital
translates signals from digital to analog
Media Converter interconnects older technologies with newer ones
a hardware device
connects newer Gigabit Ethernet technologies with older 100BaseT networks or
older copper standards with fiber
{ Specialized Network Devices }
Bandwidth Shaper
Monitors and shapes
identifies where bandwidth usage is high and the time of day
shape bandwidth usage
Traffic Shaping
used to control bandwidth usage on the network
control who uses bandwidth, for what purpose and what time
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Content Filter
controls what a user is allowed to pursue
block access to certain websites or a user
Load Balancer
workload is distributed between several servers
increases redundancy and data availability
increases performance by distributing workload
can be either a hardware device or software
Multilayer Switches
Operates as a router + switch Layer 2 + Layer 3
Content Switch
identify and forward data by its port and application
help distribute the load
1. examines the network data it receives
2. decides where the content is intended to go
3. then forwards it
Proxy Server usually part of firewall system
a server that sits between a client pc and Internet
sends request as if it originated the request
as if the request came from the proxy, not the client cp
retrieves info and returns it to the client
Caching
makes a copy of all or part of the page in its cache
when page is requested again, proxy server answers the request from thecache
allows network admins to filter client requests
can block access to certain websites
ACL - a list of allowed or unallowed websites
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Virtual Servers
a single server can host multiple logical machines
Virtual Switches
allows multiple switches to exist on same host
used with VLAN implementations
can provide a direct challenge to the virtual Ethernet adapters for config info
Open vSwitch- an open source virtual switch
Virtual PBX
(Virtual Private Branch Exchange)
phone system
handles features such as call routing, voicemail, faxing.. etc.
a service that is contracted out to a vendor routed through a vendor
they are responsible for the equipment and software
VoIP is used for routing the voice traffic
Onsite / Offsite
offsite- data center hosted elsewhere and remotely accessed
another vendor is responsible for maintaining hardware and software
(example) Electronic Monitoring Company has data come in to servers in
Colorado, but operates work with the data from workstations in Indiana
NaaS (Network as a Service)
vendors offer an entire network
freeing a company from administration
similar to Saas (Software as a Service)
OpenStack - is an open source NaaS implementation
{ Installation + Configuration }
Demarcation Point
point where the service provider stops being responsible for the line and it
becomes the technicians responsibility
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Packet Switching
messages are broken into smaller pireces calledpackets
each packet is assigned source, destination and intermediate node address
most popular switching
1. Virtual-Circuit switching uses a logical connection between the source and the destination device
2. Datagram Circuit switching
packets are independently sent and can take different paths through the
network to reach their intended destinations
packets can be routed around network congestion
Circuit Switching
offers a dedicated transmission channel that is reserved until it is disconnected
when transmission is complete, channel is closed
after physical connection is established, it is unavailable to any other sessions
until transmission completes
ISDN
used to transmit voice, video and data
uses public network, requires dial-in access
can be used for circuit-switching connections
can be used for packet-switching connections
used with copper/fiber-optic
leased from a service provider
requires dial-up access
ISDN is faster than PSTN
PSTN - used when little traffic is sent over a line. most cost-effective. limited to 56
Kbps
requires dial-up access
D Channels - carries signaling information
B Channel - carries the data
BRI ISDN - uses two B+1 D channels
PRI ISDN - uses 23 B+1 D channels
T-Carrier
used to create point-to-point network connections for private networks
uses in circuit switching
leased from telephone companies
T1
1.5 Mbps
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synonymous with DS1
T3
4.7 Mbps
synonymous with DS3
Fractional T - leasing portions of a T-carrier service
ATM
uses fixed cells that are 53 bytes long
1.544 Mbps to 622 Mbps
Cell switching
uses SVC + PVC
Frame Relay
operates at Layer 1 + Layer 2
a packet-switching technology
PVC (Permanent Virtual Circuit)
a permanent dedicated virtual link
SVS (Switched Virtual Circuit)
represents a temporary virtual circuit established and maintained
only for the duration of a data transfer sesion
SONET/OCx (Synchronous Optical Network)
defines synchronous data transfer over optical cable
delivers voice, data and video
OCx (Optical Carrier)
represent the range of digital signals that can be carried in a SONET
fiber-optic networks
each level defines the speed at which it operates
SDH - is the European counterpart of SONET
DWDM works with SONET/SDH
PON (Passive Optical Network)
services a number of different locations
uses unpowered optical splitters to split the fiver
DSL Internet Access
uses a standard phone line to provide high-speed Internet access
ADSL
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provides a high data rate in only one direction
fast download speeds but slower upload speeds
designed to work with existing POTS service
best for home-use
most common
1st Channel - responsible for analog traffic
2nd Channel - provides upload access
3rd Channel - used for downloads
HDSL
provides bidirectional high data service
VHDSL - faster version
SDSL
same speeds for both uploads and downloads
cannot share a phone line
Troubleshooting DSL
Physical connections
NIC
Drivers
protocol Configuration
DSL LEDs
Cable Internet Access
Cable Modem
uses coax connection for connecting to the providers outlet
uses UTP connection for connecting directly to a system or to a hub or
switch
uses MDI-X
shares available bandwidth with everyone else in cable area
Satellite
One-way Satellite system
requires a satellite card and satellite dish installed at users site outgoing requests sent through phone line
inbound traffic returns on satellite link
Two-way Satellite System
provides data paths for upstream and downstream data
Rain Fade = signal loss due to moisture interference
Latency = time lapse between sending info and time to return
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Line of sight = path between satellite dish and satellite
Cellular
LTE
4G upload speed = 50 Mbps
download speed = 100 Mbps
WiMax
4G
upload speed: 56 = Mbps
download speed = 1 Gbps
HSPA+
3G
{ Cabling + Wiring }
Broadband vs Baseband Transmissions
Baseband
digital signals over a single wire
bidirectional, but not at the same time
TDM (Time Division Multiplexing)
divides a single channel into time slots
Broadband use analog transmissions
FDM (Frequency Division Multiplexing)
used to create multiple channels
BPL (Broadband over Power Lines)
transmit data over lines used for electrical power
IEEE 1901 = for high-speed communication devices
IEEE 105 = for hybrid home networks
bpl = HomePlug
Simplex / Half Duplex / Full Duplex
Simplex = one-way communication of data through the network
Half-duplex = transmitting + receiving but not at same time
Full-Duplex = simultaneously transmit and receive
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Noise
any undesirable influence that degrades or distorts the signal
EMI (Electromagnetic Interference)
waves that emanate from electrical devices or cables
RFI (Radio Frequency Interferences) caused by radio waves
Crosstalk
when two wires near each other and the signal from one infringes on
signal traveling through the other wire
Attenuation
loss of signal strength as it moves farther from source
Latency
amount of time it takes electrons to move through the wire
Cabling
Twisted Pair
STP (Shielded Twisted Pair)
Max Length = 100 meters
Foil around each pair - prevents EMI
less susceptible to interference
are larger than UTP and less flexible due to shielding
UTP (Unshielded Twisted Pair)
Susceptible to interference (fluorescent light)
4 pairs of twisted wires, 8 wires total
Categories (max Length: 100 meters 328 feet) CAT1 Standard telephone cable
CAT3 10 Mbps
CAT4 16 Mbps
CAT5 100 Mbps
used with RJ-45 connectors
CAT5e 1 Gbps
CAT6 10 Gbps (55 meters)
CAT6e 10 Gbps (100 meters)
Plenum - area above suspended ceiling fire resistant cable
Coax Cable
Single core of copper
Central conductor wire surrounded by insulation which is surrounded by a
braided metal shield
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Used for Cable Modems, ISP (Internet Service provider), Cable TV and
Modem-based internet connections
All coax cables have an RG (Radio Grade) rating
The exam includes RG-6 and RG-59 (most commonly used)
both are rated at 75 Ohms
RG-49 Thinnet / 10Base2
Carries 10 Mbps of Ethernet data
Max length: 185 meters
50 ohm impedance
RG-6
Thicknet / 10Base5
10 Mbps
50-MHz or higher
Max length: 500 meters
75 ohm impedance RG-6/U
used for cable TV
75 ohms of impedance
Max length: 300 meters
Connectors:
F-type (most common)
BNC (older) screw by spinning on
75 oh impedance
Note: Baseband (Base) - only one signal at a time is sent onto the
network medium
Broadband - multiplexes the signals to allow multiple signals on
the medium
Fiber-Optic Cable
shoots pulses of light
Multi-Mode
larger core, 50 - 115 microns in diameter
62.5 microns - most common
10 Gbps
500-600 meters
uses LED (Light Emitting diodes) to send light signal
multiple sets of data at a time
Single-Mode
Narrow core, less than 10 microns
Data travels over single path
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Provides highest bandwidth and longest distance
1 Tbps
uses Laser to send light signal
3000 meters - 40 km
Throughput - up to 100 Gbps
Plenum
area above suspended ceiling
used to run network cables
plenum cables create low smoke and low toxic fumes
Coaxial Connectors
BNC
F-Connectors
Twisted Pair Connectors
RJ-45
Fiber Optic Connectors ST
SC
LC
Wiring Standards
T568-A
1. Green-White
2. Green
3. Orange-White
4. Blue
5. Blue-White
6. Orange
7. Brown-White
8. Brown
T569-B
(preferred standard)
switch up green with orange
if needed to connect T568-A with type B, use a crossover cable
Crossover Cable
A standard network cable is wired using the T568-A or B on each end
(straight-through wiring)
Crossover cable has the A on one connector and B on the other side.
Rollover Cable
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Cable that is used to connect to a Cisco Router for Configuration
aka Yost Cable
Almost 100% unique to Cisco routers
called rollover because the pinouts on one arc are reversed on the other end
as if the wire has been rolled over and you are viewing it from the opposite
side
Loopback Cable
used when troubleshooting a network issue
used to identify if the problem is with the NIC
tests NIC circuitry that sends and receives data within the NIC
does not check the actual connection pins
Network Cross-Connects
Horizontal cabling
cabling that runs from work area to Telecom Room
Run - a single piece of cable running from the work area to Telecom room
Patch Panel
makes reconfiguring/moving cables safe and easy
the front of a patch panel has female connectors (ports) for network cables
The back of patch panel has permanent connections
the horizontal cable runs are connected here
Data flow can be changed by rearranging the patch cables plugged into the front
of the patch panel
MDF (Main distribution Frame)
houses the network and telphone equipment that connects to the outside world
IDF (Intermediate Distribution Frame)
where all the horizontal runs come together
Demarcation
a location in the building where a connection is made to the outside world
for telephone & computer networks
everything inside the demarcation point is the responsibility of the network
administrator or the company
everything outside of demarcation point is the responsibility of service provider
NIU (Network Interface Unit)
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piece of equipment that established the demarcation point between your
network and the service providers network
First piece of equipment that is located inside the demarc point
marks point where technicians responsibility begins with the network
unit that allows network to interface with outside world
Demarc Extension cable used to connect to the NIU
for computer networks, 1st device inside the NIU is a powerful switch
Nicknames for NIU
Smart Jack
NIB (Network Interface Box)
NID (Network Interface Device)
CSU / DSU
used when troubleshooting a network issue
used to identify if the problem is with the NIC
tests NIC circuitry that sends and receives data within the NIC
does not check the actual connection pins
T1 (1.544 Mbps)
T3 (45 Mbps)
T1 and T3 connected telephone service to customer
is the device that connects the T1 or T3 to your network
channel service unit/ digital service unit
A CSU/DSU is required on each end of the T1 or T3 line
many new routers have it built-in to them
European counterpart to T1 and T3 are E1 and D3
Carrier Channels Speed
T1 24 1.544 Mbps
T3 672 44.736 Mbps
E1 32 2.048 Mbps
E3 512 34.368 Mbps
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Boding
bond two NICs together as one single connection physically add another NIC card on the computer, then make another cable connection to
the switch
aka Link Aggregation ; NIC Teaming
the Link Aggregation Control Protocol (LACP) controls how multiple network devices
operate as a single connection
802.3 Ethernet Standards **
10BaseT
Cable Type: Cat3 & Cat5
Max Distance: 100 meters Bandwidth: 10 Mbps
100BaseTX
Cable Type: Cat5
Max Distance: 100 meters
Bandwidth: 100 Mbps
100BaseFX
Cable Type: Fiber-Optic
Max Distance: 412 meters
Bandwidth: 100 Mbps
100BaseX
Cable Type: Fiber Optic
Max Distance: 70 km
Bandwidth: 1000 Mbps (1 Gbps)
1000BaseT
Cable Type: Cat5 & Cat5e & Cat6
Max Distance: 100 meters
Bandwidth: 1000 Mbps (1 Gbps)
1000BaseX
{ Wireless }
802.11 Wireless Standards
802.11a
Frequency: 5 GHz
54 Mbps
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Range: 20-45 meters
802.11b
Frequency: 2.4 GHz
11 Mbps
Range: 45 - 120 meters
uses WEP for security
802.11g
Frequency: 2.4 GHz
54 Mbps
Range: 30 -100 meters
compatible with 802.11a and 802.11b
802.11n
Frequency: 2.4 GHz or 5 GHz
600 Mbps
Range: 100 - 200 meters
MIMO - device can use multiple antennas
Compatible with 802.11b and 802.11g
Encryption
WEP (Wired Equivalent Privacy)
64-bit key
WPA (WiFi Protected Access)
128-bit key
WPA 2
256-bit key (best encryption)
Encryption Protocol
TKIP
AES
replaced TKIP
used in WPA2
best encryption
Extra Notes:
Packet Sniffer
used to capture network data
hardware or software device
Port Scanner
mointor traffic coming into and out of ports