Network+ Professor Messer Video Notes Flashcards
OSI Model
Open Systems Interconnection Reference Model describes how traffic moves across the network
Layer 1 - Physical Layer
signaling, cabling, connectors
not about porotocls
Layer 2 - Data Link Layer
The “switching” layer
basic network language
-the foundation of communication at the data link layer
Data Link Control (DLC) protocols
-MAC address on Ethernet
NIC , ethernet, switch
Layer 3 -Network Layer
The routing layer
-IP, router, firewall, packet
fragments frame to traverse different networks
Layer 4 - Transport Layer
The “post office” layer
-parcels and letters
-TCP and UDP
Layer 5 -Session
communication management between devices
-start, stop, restart
Control Protocols, tunneling protocols
Layer 6 - Presentation
character encoding
application encryption SSL/TLS
often combined with application layer
Layer 7 - Application Layer
the layer we see
HTTP, FTP, DNS, POP3
OSI in the real world example:
Application: https://mail.google.com
Presentation: SSL encryption
Session: Link the presentation to the transport
Transport: TCP encapsulation
Network: IP encapsulation
Data Link: Ethernet
Physical: Electrical Signals
PDU (Protocol Data Unit)
data moved from one part to another relies on PDU
Frame
each layer of the OSI model has a header and payload
TCP flags
how to process data going through network
flags control the payload
SYN - synchronize sequence numbers
PSH - push the data to the app without buffering
RST - reset the connection
FIN - last packet from sender
MTU (Maximum Transmission Unit)
maximum IP packet to transmit but not fragment
fragmentation
slows down traffic
losing fragment looses entire packet
requires overhead along path
IP fragmentation
if data needs to be sent but MTU is not enough single frames gets split up to send data
Troubleshooting MTU
MTU usually set when network created
troubleshoot using ping
-ex: Test google server
ping with DF and force max size1472 bytes
1500 bytes - 8 byte ICMP header - 20 bytes IP address = 1472
Windows ping -f -l 1472 8.8.8.8
Linux and macOS ping -D -s 1472 8.8.8.8
Star Topology
referred to as hub and spoke
all devices connected to a central device
switched ethernet network-switch is in the middle
used in most large and small networks
Ring Topology
used in many MAN and WAN networks
dual-rings
built in fault tolerance
traffic loops back if network severred
Bus Topology
early LANs
coax cable was the bus
simple but prone to errors
one break disables entire network
Mesh Topology
multiple links to the same place
fully and partially connected
redundancy, fault-tolerance, load balancing
used in WANs
Hybrid Topology
combination of one or more topologies
Wireless Topologies
Infrastructure
-all devices communicate through AP
-most common wireless communication mode
Ad hoc networking(if no AP)
-no pre existing infrastructure
-devices communicate amongst themselves
Mesh
-ad hoc devices work together to form a mesh ‘cloud’
-self form and self heal
Peer to Peer Network
every device is a server and a client
everyone talks to everyone
advantages: easy to deploy, low cost
disavantages: difficult to administer and secure
Client Server Network
clients talk to server
no client to client communication
advantages: performance, administration
disadvantage: cost, complexity
LAN Network
Local Area Network
a building or group of buildings
Ethernet and 802.11 wireless
any slower isnt local
MAN Network
a network in your city
larger than LAN smaller than WAN
common to see government ownerships
WAN Network
Wide Area Network
spanning the globe
connects LAN across distance slower than LAN
point to point, MPLS examples of WAN
WLAN
wireless LAN
802.11 networks
within a bldg
in a limited geo area
expand coverage with access points
PAN
Personal Area Network
-own private network
-Bluetooth, IR, NFC
Automobile
-audio output
-integrate with phone
Mobile Phone
-wireless headset
Health
-workout telemetry, daily reports
CAN
Campus Area Network
-corporate area network
limited geo area
-a group of bldgs
LAN tech
-fiber connected
-high speed ethernet
your fiber in the ground
- no third party provider
NAS vs SAN
Network Attached Storage - file level access - connects to local storage
Storage Area Network - looks and feels like local storage device
-block level access
-very efficient reading and writing
-requires a lot of bandwidth
MPLS
Multiprotocol Label Switching - communication through the WAN uses labels how we route and forward traffic through WAN
-any transport medium any protocol inside
-labels are pushed onto packets as they enter MPLS cloud
-labels are popped off on the way out
mGRE
Multipoint Generic Router Encapsulation
-used extensively for Dynamic Multipoint VPN (DMVPN)
-common on cisco routers
-VPN builds itself
-tunnels are built dynamically on demand
-dynamic mesh
SD-WAN
Software Defined WAN
-WAN built for the cloud
-cloud base apps communicate directly to cloud
-
demarcation point
point where you connect with the outside world
Ex; can be as simple as RJ - 45 connection
smartjack
Network interface unit(NIU)
on the wall
locked
blinking light
owned by the network provider
determines the demarc
NFV
network function virtualization
replace physical with virtual networks
vSwitch
move physical switch to virtual environment
1000BASE-T
Category 5 - 100meters
1000BASE-T
Category 5e -100meters
10GBASE-T
Category 6 - unshielded is 55 meters and shielded is 100m
10GBASE-T
Category 6a - 100m
10GBASE-T
Category 7(shielded only) - 100m
40GBASE-T
Category 8 (shielded only) - 30 m
IEEE 802.3 Ethernet Standards
1000BASE-T, 10GBASE-T, 40GBASE-T
T568A
pin out to horizontal cabling
starts with green
T568B
traditionally used difficult to change midstream
starts with orange
core
highly reflective core inside fiber
cladding
low reflective protects fiber core
multimode fiber MMF
short range up to 2km
core is larger than light
single mode fiber SMF
smaller core one mode of light transmits through core
used for long distances up to 100km
laser beams
more expensive than MMF
ST
straight tip connector
plug and twist
SC
subscriber connector
square connector
locking mechanism pushed in it locks
MT RJ
Mechanical Transfer Registered Jack
push down pull
max amount of fiber in the smallest connector
UPC
Ultra Polished Connector
high return loss
ferrule 0 degree angle
APC
Angle Polished Connector
lower return loss
ferrule 8 degree angle
return loss
how much light is reflected back to the source
RJ 11
6 position 2 conductor 6P2C
Telephone and DSL connection
RJ 45
8 position, 8 conductor (8P8C)
F-connector
coax connector found on a cable modem typically
RG-6 cable and threaded
insert and twist
Media Converter
operates at physical layer 1
can extend a copper wire over a long distance and convert it to fiber
trasciever
transmitter and receiver in a single component
Bi-Directional trancievers (Bi-Di)
send and receive traffic over a single strand of fiber
SFP Small From Factor Pluggable
commonly used to provide 1 Gbit/s fiber
SFP+ Enhanced Small Form Factor Pluggable
enhanced to increase throughput supports rates up to 16 Gbits
common with 10Gb internet
QSFP Quad Small Form Factor Pluggable
4 channel SFP four 1 Gbits for a total of 4 Gbits
QSFP+ Quad Small Form Factor Pluggable
four channel SFP+ = four 10 Gibit = 40 Gibit
66 block
patch panel for analog voice
left side is patched to the right
wire is punched into the block using a punchdown tool
110 blocks
wire to wire patch panel
patch cat 5 and cat 6
wires are punched into the block
krone block
used in Europe alternative to 110 block
analog and digital communication
BIX building industry cross connect block
can support cat 6 and better updated through the years since 1970
Private IPv4 address (RFC 1918)
10.0.0.0-10.255.255.255
172.16.0.0-172.31.255.255
192.168.0.0-192.168.255.255
Network Address Translation (NAT)
translates private IP addresses to public IP address through the router and vice versa
NAT overload/PAT port address translation
through router translates IP address and port number
unicast
one to one
broadcast
one to all
multicast
one to many of many
anycast
one to one of many
IPv4 and IPv6
classful subnetting
class A, B, C, D, E
Class E
reserved range 1111(240-254)
Class D
multicast 1110 (224-239)
Class C
110 (192-223)
Class B
10 (128-191)
subnet mask
contiguous series of ones
ex: 11111111 11111111 11111111 00000000
/24
CIDR block notation/slash notation/prefix notation
CIDR block notation
how many 1s are/how many bits are in binary
network vs host bits
in a binary notation 1s are network bits and 0s are host bits
Why subnet a network?
very difficult to connect all devices in the network
VLSM Variable Length Subnet Masks
customize subnet mask to specific requirements
powers of two
2^16 = 65,536
2^15 = 32,768
2^14 = 16,384
2^13 = 8,192
2^12 = 4,096
2^11 = 2,048
2^10 = 1,024
2^9 = 512
2^8 = 256
2^7 = 128
2^6 = 64
2^5 = 32
2^4 = 16
2^3 = 8
2^2 = 4
2^1 = 2
number of subnets =
2^subnet bits
hosts per subnet =
2^hosts bits - 2
What other address never changes?
MAC Address
EUI
Extended Unique Identifier 48-bit
converting EUI 48 to EUI 64
split the MAC (24 bits) and put FFFE in the middle (the missing 16 bits)
flipping the 7th bit (MAC address)
create a chart and change it to to the other value
LC
Local Connect
push down pull
