The Network Layer.

• IP Adresses
  IP addresses belong to networks, not to the devices
  attached to those networks.

• IP datagram
  A highly structured series of fields that are strictly defined.

• ARP(Address Resolution Protocol)
  A protocol used to discover the hardware address of a node with a certain IP addresse.

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Subnetting

the process of taking a large network and splitting it up into many individual smaller subnetworks or subnets.

• Subnet Masks
  32-bit numbers that are normally written out as four octets in decimal.

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Router

A network device that forwards traffic depending on the destination addresses of that traffic

Basic Routing

1. Receive data packet.
2. Examines destination IP
3. Look up IP destination network in routing table.
   4.Forwards traffic to destination.

• Autonomous system
  A collection of networks that all fall under the control of a single network operator
• Interior gateway protocols
  Used by routers to share information within a single autonomous system.
• Exterior gateway protocols
  Used to communicate data between routers representing the edges of an autonomous system.