CompTIA Network+ (N10­005)
✓ 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
➢ Peer­to­Peer
● 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 ­ network’s physical layout of computer cables/devices
● logical topology ­ the way in which the network appears to the devices that
use it
➢ Bus
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➢ Ring
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➢ Star
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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
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
all computers connect to a central device (hub or switch)
each connected device requires a single cable to be connected
■ creates a point­to­point (PtP) connection
easiest to expand and add devices
most popular
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➢ Mesh
● each computer on network connects to every other computer
■ point­to­point (PtP) with each computer
● provides high level of redundancy
● better fault tolerance
● to calculate number of connections in a mesh
■ y(y­1)/2 ; y = # of computers | 5 computers = 10 connections
➢ Hybrid
● combines different kinds of topologies
➢ PtP (Point­to­Point)
● 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 (Point­to­MultiPoint)
● 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 point­to­point 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 (Point­to­Point Tunneling Protocol)
○ L2TP (Layer 2 Tunneling Protocol)
○ enables authentication and encryption to protect data from
general public
● LAN­to­LAN
■ 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
■ Protocol­based = assigned by their protocol in use and the Layer 3
■ Port­based = the ports of the switch are configured to belong to the
various VLAns
■ MAC address­based = assigns membership according to the
workstation’s MAC address
■ Subnet­based = 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
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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
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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
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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 flow­control
○ Will make sure not too much data is being sent; waiting
period for data is not too long; data that was damaged gats
re­sent
■ 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
○ it’s 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
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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 of
manageable sized for the lower layers (and opposite for upper layers)
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data is transferred over network in two ways:
■ UDP ­ connectionless
○ excellent for data that must be delivered asap
○ (examples) video, walki­talkie radio, etc.
○ no confirmation
■ TCP ­ connection­oriented
○ connection is established before communication begins
○ data is delivered in sections
○ confirmation system is used to make sure the data was
delivered
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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 can’t 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 end­user 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
● connection­oriented
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responsible for guaranteed delivery of data
■ offers flow control, sequencing, retransmission of dropped packets
● TCP three­way 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 file­management 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)
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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 (Real­time Transport Protocol)
● for transporting real­time 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 hostname­to­IP 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 = second­level domain
■ .org = top­level domain
➢ reverse lookup
● IP address­to­hostname
● accomplished by using Pointer Records (PTR)
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➢ 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, read­only 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 protocol­dependent, not platform­dependent.
➢ 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 dhcpoffer packet
● 4. Client receives offer, determines if it is suitable
● 5. Client sends back dhcprequest packet
● 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
Loopback Address
IPv6
127.0.0.1
::1
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
Site­local Address ranges
FEC0::
Autoconfigured addresses
APIPA: 169.254.0.1 ­ 169.255.254.0
Link­local Addresses
FE80::
Network­wide addresses
✓ 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 router’s 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: Distance­Vector Routing & link­state
➢ Distance­Vector 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
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➢ Link­State Routing
● build a map of entire network and then holds the map in memory
● updates occur less frequently
● OSPF (Open Shortest Path First)
■ least­cost path
■ used in medium to large enterprise networks
● IS­IS
■ 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
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✓ 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
bridge­learning process
➢ Transparent Bridge
● devices on network don’t 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
➢ Cut­through ­ packet just gets forwarded, no error check
➢ store­and­forward ­ 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
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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
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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 the
cache
➢ 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
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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
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(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 called packets
each packet is assigned source, destination and intermediate node address
most popular switching
1. Virtual­Circuit 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
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✓ 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
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used to transmit voice, video and data
uses public network, requires dial­in access
can be used for circuit­switching connections
can be used for packet­switching connections
used with copper/fiber­optic
leased from a service provider
requires dial­up access
ISDN is faster than PSTN
PSTN ­ used when little traffic is sent over a line. most cost­effective. limited to 56
Kbps
● requires dial­up access
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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
✓ T­Carrier
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used to create point­to­point 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 T­carrier service
✓ ATM
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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 packet­switching 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
fiber­optic 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 high­speed 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 home­use
most common
●
●
●
1st Channel ­ responsible for analog traffic
2nd Channel ­ provides upload access
3rd Channel ­ used for downloads
➢ HDSL
●
●
➢ SDSL
●
●
provides bidirectional high data service
VHDSL ­ faster version
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 provider’s outlet
● uses UTP connection for connecting directly to a system or to a hub or
switch
● uses MDI­X
● shares available bandwidth with everyone else in cable area
✓ Satellite
➢ One­way Satellite system
● requires a satellite card and satellite dish installed at user’s site
● outgoing requests sent through phone line
● inbound traffic returns on satellite link
➢ Two­way 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 high­speed communication devices
● IEEE 105 = for hybrid home networks
● bpl = HomePlug
✓ Simplex / Half Duplex / Full Duplex
➢ Simplex = one­way communication of data through the network
➢ Half­duplex = transmitting + receiving but not at same time
➢ Full­Duplex = 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 RJ­45 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
Modem­based internet connections
All coax cables have an RG (Radio Grade) rating
■ The exam includes RG­6 and RG­59 (most commonly used)
■ both are rated at 75 Ohms
RG­49
■ “Thinnet” / “10Base2”
■ Carries 10 Mbps of Ethernet data
■ Max length: 185 meters
■ 50 ohm impedance
RG­6
■ “Thicknet” / “10Base5”
■ 10 Mbps
■ 50­MHz or higher
■ Max length: 500 meters
■ 75 ohm impedance
RG­6/U
■ used for cable TV
■ 75 ohms of impedance
■ Max length: 300 meters
Connectors:
■ F­type (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
➢ Fiber­Optic Cable
● shoots pulses of light
● Multi­Mode
■ larger core, 50 ­ 115 microns in diameter
62.5 microns ­ most common
■ 10 Gbps
■ 500­600 meters
■ uses LED (Light Emitting diodes) to send light signal
■ multiple sets of data at a time
● Single­Mode
■ 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
● F­Connectors
➢ Twisted Pair Connectors
● RJ­45
➢ Fiber Optic Connectors
● ST
● SC
● LC
✓ Wiring Standards
➢ T568­A
● 1. Green­White
● 2. Green
● 3. Orange­White
● 4. Blue
● 5. Blue­White
● 6. Orange
● 7. Brown­White
● 8. Brown
➢ T569­B
● (preferred standard)
● switch up green with orange
➢ if needed to connect T568­A with type B, use a crossover cable
✓ Crossover Cable
➢ A standard network cable is wired using the T568­A or B on each end
(straight­through 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 Cross­Connects
➢ 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 provider’s 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 built­in 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: Fiber­Optic
● 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
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