====== Network ======

==== OSI Model ====

The OSI (Open System Interconnect) Model was developed in 1984 as an open standard to promote network interconnection and interoperability.

^  Layer  ^  Function  ^ Examples  ^
|  7. Application  |  **End User :** Support for applications  | HTTP, FTP, SMTP (email) |
|  6. Presentation  |  **Syntax :** Protocol conversion, structures data for the application  | ASCII, JPEG, etc. |
|  5. Session  |  **Sync & Ports :** Establishes, manages and terminates sessions & connections  | NFS, SQL |
|  4. Transport  |  **End to End Connection :** Is concerned with message integrity between source and destination  | TCP, UDP |
|  3. Network  |  **Packets :** Combines messages into packets, adding routing information  | IP, IPX |
|  2. Data Link  |  **Frames :** Handles flow control, sequencing, errors  | MAC |
|  1. Physical  |  **Cables :** Provides electrical and mechanical connections to the network  | cables and NIC |

==== MAC Addresses ====
Written in hexadecimal notation, composed of 12 digits, the first 6 correspond to the **O**rganizational **U**inque **I**dentifier (**OUI**) and the last 6 are given by the manufacturer to each device. Every MAC address should be **unique**.

Large manufacturers may have many several OUI.

===== Fiber Optics =====

[[network:fiber-optics|Fiber Optics Section]]


===== Glossary =====

  ***DOS :** **D**isk **O**perating **S**ystem
    *//The ancestor to Windows.//

  ***HAL :** **H**ardware **A**bsraction **L**ayer
    *//Used in virtualization technology.//

  ***MAC :** **M**edia **A**ccess **C**ontrol
    *//Unique identifier for any network device.// [[network:start#mac_addresses|See here.]]

  ***NAT :** **N**etwork **A**ddress **T**ranslation
    *//Allows the translation of multiple local private addresses into a single public IP. Used in most home routers.// [[https://www.comptia.org/content/guides/what-is-network-address-translation|More info]]

  ***NTFS :** **N**ew **T**echnology **F**ile **S**ystem
    *//A file system used by Windows.//

  ***OUI :** **O**rganizational **U**nique **I**dentifier
    *//First part of the MAC address used to identify the manufacturer.//

  ***SSID :** **S**ervice **S**et **Id**entifier
    *//Name used to identify it wireless networks from one another.//

  ***WAN :** **W**ide **A**rea **N**etwork
    *//Large network not tied to a single location but spread across several locations.// [[https://www.comptia.org/content/guides/what-is-a-wide-area-network|More info]]
===== Upcoming =====

  *Define kernels
  *Expand upond Topology (architectures)
  *List IANA somewhere (assigns IP addresses to the network and ensures their unicity)
  *Expand upon private IP addresses reserved (p. 50)
  *Talk about firewalls and Stateful Packet Inspection
  *Detail WAN/MAN/LAN
  *Detail NIC & MAC
  *Expand protocol / topology / deterministic
  *Compare hub vs switches
  *CSMA/CD
  *Ethernet Frame
  *Class of IP addresses
  *wired vs wireless (cite 3 advantages of each)