Master the Network Layer and Data Plane

Network Layer

• Responsible for transporting segments from the sending to the receiving host

Routers

• Contain a routing table which maps network addresses to outgoing interfaces
• Contain a forwarding engine

Routing Protocols

• Use path-selection algorithms to compute best paths between networks
• Path selection algorithms determine which paths are best and why

ICMP Protocol

• Internet Control Message Protocol
• Facilitates error reporting and control messages between hosts and routers
• Used to report error messages

Network Layer

• Responsible for examining header fields in all IP datagrams
• Necessary for ensuring datagrams are delivered correctly

IP Addresses

• Logical addresses used to identify devices on a network
• Allow devices to communicate with one another across different networks
• Unique identifiers for each device

Subnetting

• Divides a large network into smaller subnetworks
• Enables efficient routing and traffic management
• Improves network security by isolating traffic within subnets

IPv4 Address Structure

• Four octets (groups of eight bits) separated by periods
• Each octet represents a number between 0 and 255
• Example: 192.168.1.1

NAT

• Network Address Translation
• Allows multiple devices on a private network to share a single public IP address on the internet
• Provides a layer of security by hiding internal network addresses from external networks

Subnet

• A logical division of a larger network
• Used to isolate traffic and improve network performance
• Example: all devices on a subnet can communicate with each other, but not with devices on other subnets