Part 1 Flashcards
All People Seem To Need Data Processing
Application, Presentation, Session, Transport, Network, Data Link, Physical
Physical Layer
Electronic signals creating connection. Physical wires, ports, or wireless communication. Data is transferred as bits.
Data Link Layer
Also called Data Link Control Layer or MAC layer. Describes the ethernet connection between two NIC cards. These NIC cards will have MAC (Media Access Control) Addresses to identify source and destination. Switches handle device communication via MAC addresses.
Network Layer
The IP (Internet Protocol) layer. Describes how devices route information to other devices located in a different network.
Transport Layer
Transportation protocols including TCP and UDP that negotiate and or establish connections between devices. These protocol also have designated ports for different types of traffic.
Session Layer
Session management that connects and controls information flow. Connects Application and Presentation layer data to the rest of the OSI stack layers.
Presentation Layer
Manages SSL/TLS encryption of data communication.
Application Layer
Data that you see and interact with within an application on your screen.
PDU
Packet Datagram Unit - Each layer of the OSI model encapsulates data from the layer above it often between and head and tail packet. The layer doing the encapsulation does not care what the data within it is. The encapsulating layer will reference the head and tail packets of the encapsulated data to know where the data needs to be sent and other meta data.
MTU
Maximum Transmission Unit - Maximum amount of bytes allowed over a connection before a packet is required to be fragmented. Packet fragmentation can slow down a connection as the packets have to be reconstructed by the receiving node. Fragmentation also increases the chances of data loss/failed connection.
Peer to Peer
All devices are both clients and servers. Easy to deploy and cheap. Difficult to administer and secure.
Client-Server
Central server that clients talk to each other through. Better performance and easier administration. More expensive and complex.
LAN
Local Area Network : Local is relative. Could be a building or group of building. Consists of ethernet or wireless (802.11) connections to provide high speed connectivity.
MAN
Metropolitan Area Network : A network in your city. Larger than a LAN but smaller than a WAN. Common for government organizations who own fiber cabling around a city.
WAN
Wide Area Network: Spanning the globe. Generally connects LANs across a distance. Generally much slower than a LAN. Many different WAN connections such as satellite, point to point serial, fiber, etc.
WLAN
Wireless LAN: 802.11 Technologies. Within a building (geofencing). Can expand coverage with additional access points.
PAN
Personal Area Network: Your own private network. Consists of Bluetooth, IR, NFC. Includes tech like headphones, cars, workout telemtry.
CAN
Campus Area Network: Limited geographical area network, or a group of buildings. Fiber connected or through high speed ethernet.
NAS
Network Attached Storage: Connected to a shared storage device across the network. File level access, so any changes you make to the file have to be made to the entire file. Requires a lot of connection bandwidth.
SAN
Storage Area Network: Looks and feels like a local storage device (Block level access). Very efficient reading and writing. Requires a lot of bandwidth.
MPLS
Multiprotocol Label Switching: Labels traffic moving through WAN connection. Allows for transport for any medium and any protocol inside. A common WAN technology. Labels are pushed onto packets as they enter the MPLS cloud. Labels are popped off on the way out.
mGRE
Multipoint Generic Router Encapsulation: Used extensively for Dynamic Multipoint VPN and common for CISCO routers. Your VPN builds itself and remote sites communicate to each other. Tunnels are built dynamically on demand.
SD-WAN
Software Defined WAN: a WAN built for the cloud. Datacenters used to be in one place. Cloud based applications communicate directly to cloud resources instead of through a datacenter. Data is forwarded to a destination based on its traffic.
Demarcation Point
The point where you connect to the internet via ISP or WAN provider. Used everywhere in offices and buildings. This is what you connect you customer premises equipment such as routers and switches.
Smartjack
A smart network interface unit (NIU) that determines the demarc and provides built in diagnostics such as loopback tests and alarm indicators.
NFV
Network Function Virtualization: Virtualize all physical network devices and manage from a hypervisor. Quickly and easily deploy network functions with many different deployment options like VMs, Containers, fault tolerance, etc.
Hypervisor
Virtual machine manager for the virtual platform and guest operating systems. Hardware manager and allows for single console control.
vSwitch
Virtual Switch with same functionality as a physical switch. Can do link aggregation, port mirroring, forwarding options, netflow. Deployed from the hypervisor.
vNIC
Virtual NIC: virtual devices need a network interface. Can be configure and connected through a hypervisor.
Satellite networking
Communication to a satellite. High cost relative to terrestrial networking and made for remote sites. High latency that requires high frequencies for comms.
Copper
Extensivley used because its cheap and easy to install and maintain. Limited bandwidth availability because of physics limiting electronic signals over copper. Used in wide area networks such as cable modem and DSL. Often combined with fiber that resides on the backbone of a connection.
DSL
Digital Subscriber Line: Uses pre-existing phone lines. Download speeds are faster than upload speeds (asymmetric). Faster speeds are possible depending on proximity to a central office location (CO).
Cable Broadband
Broadband comms with transmission across multiple frequencies and different types of traffic. Use a specific standard called DOCSIS (Data Over Cable Service Interface Specification). Broadband speeds will vary depending on DOCSIS spec in use.
Fiber
High speed data communication over light frequencies. Higher installation and maintenance costs than copper. Will make up the bulk of the core installation for a WAN.
Metro Ethernet
Metro Area Networks connected via ethernet. Local networks will be ethernet based and provider network will be optical.
Twisted Pair Copper Cabling
Ethernet copper wire pairing. Two wires are twisted with equal and opposite signals (Transmit +, Transmit - / Receive +, Receive -). The twist allows for reduced interference.
Coaxial Cables
Two or more forms using the same common axis. Used in television/digital cable connectivity.
Twinaxial Cable
Two inner conductors. Common on 10GB ethernet connections that are full duplex, low cost, low latency, but short range (5m).
T568A/T568B Termination
Ethernet twisted pair copper termination standards. Many organizations used 568B because it’s more difficult to change mid-stream. A and B can’t be used together.
Multimode Fiber
Short range communication (2km) with multiple light modes used for comms. Uses LED so inexpensive.
Single-mode Fiber
Long range comms (100km). Requires lasers as light source which is expensive.
Fiber Communication
Transmission by light. No RF signal so difficult to tap or monitor and low interference. Signal is slow to degrade and can transfer over longer distances.
LC
Local Connector (Fiber). One send and one receive tip. Small and popular.
ST
Straight Tip (Fiber) - Use bayonet connectors that requiring twisting and untwisting send and receive pins.
SC
Subscriber Connector (Fiber) - Square send and receive pins.
MT-RJ
Mechanical Transfer Register Jack - smallest fiber connector. Locking mechanism and square.
UPC
Ultra-polished Connectors - Ferrules are connected at 0 degree angle. Have a high return loss.
APC
Angle-polished connectors - Ferrules are connected at an 8 degree angle. Lower return loss but higher insertion loss than UPC.
RJ11 Connector
Used for telephone and DSL connection. 6 positions 2 conductors (6P2C).
RJ45 Connector.
8 position 8 conductor (8P8C). Used for ethernet.
Media Converter
OSI Layer 1 signal conversion. Allows for converting between copper to fiber and vice versa. Mostly required to be powered.
Transceiver
Transmitter and receiver usually in a single modular component. Allows for different connections like fiber to copper. Different signal types based on the type and design of the transceiver. Can double fiber connections with bi directional transceivers.
SFP and SFP+
Small Form Pluggable and Enhanced Small Form Pluggable transceivers used to provid 1GB/16GB fiber connections. Ethernet SFPs are available as well.
QSFP
Quad Small Form Factor Pluggable. 4 channel SFP = 4 1GB connections. Also comes in enhanced version which = 40GB. Bi-directional versions also available. Useful when there are limited ports for transceivers.
Copper Patch Panel
Provides cable management in office space with cables running from panel through the floor/ceiling to desks. Punch-down block on one side of panel and RJ45 connector on the other side.
Fiber Distribution Panel
Permanent Fiber installation with patch panel at both ends. Fiber cables have a maximum bend radius so that they don’t break. Panels also include a “service loop” that provides extra fiber cable in case the panel needs to be moved.
66 Block
Patch panel for analog voice connections. Wires were punched down to connectors within the panel. Generally replaced by 110 blocks as digital comms took over.
110 Block
Wire to wire patch panel that replaced 66 blocks. Used to patch cat 5 and cat 6 cables.
Krone Block
European version of 110 block. Supports analog and digital comms and various signals.
BIX
Building Industry Cross Connect: Created in 70s as common block type. Newer versions have Gig connections speeds that perform as good as Cat6 cables or better.
WDM
Wavelength Division Multiplexing: Bidirectional communication over a single strand of fiber for multiple types of signals. Use different wavelengths for each carrier.
Binary to Decimal
Eight numbers all the way up to 2^8. 0 or 1 below all eight numbers. If below number is 1, drop down the top number. Add up all top number values where the lower values equal 1.
Decimal to Binary
Eight numbers all the way up to 2^8. 0 or 1 below all eight numbers. When given a decimal number, determine if top number values are greater than or equal to the given value. Move from left to right high to low top number values. If a following value goes over the given decimal number, the bottom value is assigned 0, else it’s assinged a 1.
Subnet Mask
Used by the local device to determine what subnet it’s on. Not usually transmitted during TCP/IP communications.
Default Gateway
The routing address that allows you to communicate outside of your local subnet. Must be an IP address on the local subnet.
Loopback Address
An address for your local host. Usually 127.0.0.1. Useful for ping troubleshooting if your system has issues with it’s TCP/IP stack.
Reserved Addresses
Set aside for future use or testing. 240.0.0.1 through 254.255.255.254. These are known as class E addresses.
VIP
Virtual IP Address - not associated with a physical network adapter. Used for virtaul machines or routers.
DHCP
Dynamic Host Communication Protocol: Provides automatic address and IP configuration for almost all devices.
APIPA
Automatic Private IP Addressing:
An automatically assigned link local address. Traffic is not routable. ARP request sent to confirm address is not in use. 169.254.1.0-169.254.254.255.
Class A Private
10.0.0.0-10.255.255.255
Class B Private
172.16.0.0-172.31.255.255
Class C Private
192.168.0.0-192.168.255.255
NAT
Network Address Translation: protocol that takes a private IP addresses and transforms it to a public IP address when connecting to devices over the internet. Port address translation required when multiple devices in a private network need to communicate externally over the internet.
Unicast
One to one communication between devices. Does not scale well. IPv4 and IPv6.
Broadcast
One to all communication between devices. One packed is sent and received by everyone on the local network. Used for routing updates and ARP requests. Can cause network performance issues. Only used by IPv4.
Multicast
Delivery of information to interested systems. Requires specific configuration and is difficult to scale across large networks. Used in IPv4 and IPv6.
Anycast
Single destination IP address has multiple paths to two or more devices. One to one of many. Used by IPv4 and IPv6. Packets sent to an anycast address are delivered to the nearest interface. Used for DNS.
Network Address
The first IP address of a subnet. Set all host bits to 0 (0 Decimal). AKA Subnet ID
First Usable Host
One number higher than network address.
Broadcast Address
The last IP address of a subnet. Set all host bits to 1 (255 Decimal).
Last Usable Host Address
One number lower than the broadcast address.
Local Link Controller
Sublayer protocol of the Data link layer NIC that communicates with the operating system via drivers.
