Basic Routing Concepts

Learning goal: Describe the basics of routing and how routing tables work.

Define some of the major routing protocols and what they do and identify non routable address space and how it’s used

Gain an understanding of the RFC system and how it made the inter what it is today

Today most intensive routing issues are almost exclusively handled by ISPs and only the largest of companies.

Router: A network device that forwards traffic depending on the destination address of that traffic

Basic routing steps:

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

Untitled

Example:

Untitled

IP addresses belong to the network not individual nodes inside the network.

computer A, 192.168.1.100 sends data to computper B, 10.0.0.10

Since the computer knows 10.0.0.10 isn’t on the same network it sends the packet to the the mac address of its gateway, the router.

Untitled

Router receives the packet and strips away the data-link encapsulation leaving the network layer content.

By inspecting the content router knows 10.0.0.0/24 is the correct network for the destination IP.