TCP/IP Architecture and IPv4 vs IPv6

Definition: A set of protocols for communication over the internet, consisting of four layers.
Layers:
1. Application Layer: Interfaces directly with user applications (e.g., HTTP, FTP).
2. Transport Layer: Provides end-to-end communication services (e.g., TCP, UDP).
3. Internet Layer: Responsible for packet forwarding (e.g., IP, ICMP).
4. Link Layer: Manages physical network connections (e.g., Ethernet).

Address Length:
- IPv4: 32 bits (about 4.3 billion addresses).
- IPv6: 128 bits (about 340 undecillion addresses).
Address Format:
- IPv4: Decimal format (e.g., 192.168.1.1).
- IPv6: Hexadecimal format (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).
Header Complexity:
- IPv4: More complex header with optional fields.
- IPv6: Simplified header, leading to more efficient processing.
Configuration:
- IPv4: Manual or DHCP configuration.
- IPv6: Stateless Address Autoconfiguration (SLAAC) and DHCPv6.
Security:
- IPv4: IPsec is optional.
- IPv6: IPsec is mandatory.

Purpose: Monitoring and analyzing network traffic to improve performance, security, and troubleshooting.
Tools: Wireshark, tcpdump, NetFlow.
Key Metrics:
- Throughput: Rate of successful message delivery.
- Latency: Time taken for data to travel from source to destination.
- Packet Loss: Percentage of packets lost during transmission.
Techniques:
- Deep Packet Inspection: Analyzing packet data for patterns.
- Flow Analysis: Monitoring data flow between devices.

Types:
- Public IP Address: Routable on the internet, unique across the globe.
- Private IP Address: Not routable on the internet, used within local networks (e.g., 192.168.x.x, 10.x.x.x).
Reserved Addresses:
- Loopback (127.0.0.1 for IPv4).
- Link-local addresses (169.254.x.x for IPv4; fe80::/10 for IPv6).

Definition: Dividing a network into smaller, manageable sub-networks (subnets).
Benefits:
- Improved performance and security.
- Better utilization of IP addresses.
Subnet Mask: Defines the network and host portions of an IP address (e.g., 255.255.255.0).
CIDR (Classless Inter-Domain Routing): Allows more flexible allocation of IP addresses (e.g., /24 denotes a subnet mask of 255.255.255.0).
Calculating Subnets:
- Determine the required number of subnets.
- Use the formula 2^n ≥ required subnets (n = number of bits borrowed).
- Adjust the subnet mask accordingly.

Set of communication protocols structured in four layers: Application, Transport, Internet, and Link.
Application Layer: Direct interaction with user applications like HTTP and FTP.
Transport Layer: Manages end-to-end communication using protocols such as TCP and UDP.
Internet Layer: Handles packet forwarding utilizing IP and ICMP protocols.
Link Layer: Operates physical network connections, commonly through Ethernet.

Address Length:
- IPv4 has a length of 32 bits, providing approximately 4.3 billion unique addresses.
- IPv6 extends to 128 bits, accommodating around 340 undecillion addresses.
Address Format:
- IPv4 uses a decimal format (e.g., 192.168.1.1).
- IPv6 adopts a hexadecimal format (e.g., 2001:0db8:85a3::8a2e:0370:7334).
Header Complexity:
- IPv4 features a more intricate header with optional fields.
- IPv6 simplifies the header for enhanced processing efficiency.
Configuration Options:
- IPv4 can be configured manually or via DHCP.
- IPv6 supports Stateless Address Autoconfiguration (SLAAC) alongside DHCPv6.
Security Features:
- IPv4 includes IPsec as an optional feature.
- IPv6 mandates IPsec for all communications.

Involves monitoring and analyzing data traffic to enhance performance and security while aiding troubleshooting.
Utilizes tools such as Wireshark, tcpdump, and NetFlow for efficient analysis.
Key Metrics:
- Throughput: The rate at which successful messages are delivered.
- Latency: The time required for data to travel from a source to its destination.
- Packet Loss: The percentage of packets that fail to reach their intended destination.
Techniques Employed:
- Deep Packet Inspection: Detailed analysis of packet data to identify traffic patterns.
- Flow Analysis: Monitoring and examining data flow between devices on the network.

Types of IP Addresses:
- Public IP Address: Routable across the internet, must be unique globally.
- Private IP Address: Unroutable on the internet, used within local networks (notable examples include 192.168.x.x, 10.x.x.x).
Reserved Addresses:
- Loopback Address: 127.0.0.1 is used for loopback testing in IPv4.
- Link-local Addresses: IPv4 uses 169.254.x.x and IPv6 uses the range fe80::/10 for link-local addressing.

Involves subdividing a network into smaller, manageable units known as subnets.
Provides benefits such as enhanced performance, improved security, and efficient use of IP addresses.
Subnet Mask: Determines which part of an IP address represents the network versus the host (e.g., 255.255.255.0).
CIDR (Classless Inter-Domain Routing): Introduces flexibility in IP address allocation, where notation such as /24 indicates a subnet mask of 255.255.255.0.
Calculating Subnets:
- Assess the number of required subnets.
- Apply the formula 2^n ≥ required subnets, where n represents the number of bits borrowed.
- Adjust the subnet mask accordingly for optimal allocation.