🔀 IP Protocols – TCP/IP, UDP, IPSec, IPMC
Deep dive into the key IP-based protocols including TCP, UDP, IP Multicast, and IPSec with its modes and components.
🌐 IP Protocols – TCP/IP, UDP, IPMC, and IPSec
Internet communication relies on a group of protocols that define how data travels across networks. This guide explores core IP-based protocols including TCP/IP, UDP, IP Multicast (IPMC), and IPSec for secure communication.
📦 TCP/IP Stack Overview
The TCP/IP model is a simplified version of the OSI model with 4 layers:
| Layer | Protocols / Functions |
|---|---|
| Application | HTTP, FTP, DNS, SMTP, SSH, etc. |
| Transport | TCP, UDP |
| Internet | IP, ICMP, IGMP |
| Network Access | Ethernet, Wi-Fi, PPP |
🔀 TCP vs UDP
✅ TCP (Transmission Control Protocol)
- Connection-oriented
- Reliable delivery
- 3-way handshake
- Use cases: HTTP, SSH, FTP, Email
⚡ UDP (User Datagram Protocol)
- Connectionless
- Fast but unreliable
- Use cases: DNS, VoIP, Video Streaming, Gaming
🔁 Quick Comparison
| Feature | TCP | UDP |
|---|---|---|
| Connection | Yes | No |
| Reliability | Guaranteed delivery | No guarantees |
| Overhead | High | Low |
| Speed | Slower | Faster |
📢 IPMC – IP Multicast
IP Multicast (IPMC) allows a single sender to deliver data to multiple receivers simultaneously using a group address.
- Uses Class D IPs:
224.0.0.0 – 239.255.255.255 - Efficient for streaming, IPTV, online conferencing
- Common Protocols:
- IGMP (Internet Group Management Protocol) – Used by hosts to join/leave multicast groups
- PIM (Protocol Independent Multicast) – Used by routers to manage multicast traffic
🔐 IPSec – Internet Protocol Security
IPSec is a suite of protocols for securing IP communications at the Network Layer (Layer 3). It offers encryption, integrity, and authentication.
🔧 Modes of IPSec
| Mode | Description |
|---|---|
| Tunnel Mode | Entire IP packet is encrypted and encapsulated in a new IP header (used between gateways) |
| Transport Mode | Only the payload (not the header) is encrypted (used between end devices) |
🔐 IPSec Protocols
✅ AH – Authentication Header
- Provides authentication and integrity
- No encryption (data is not hidden)
✅ ESP – Encapsulating Security Payload
- Provides encryption, authentication, and integrity
- Supports both Tunnel and Transport modes
🔁 IKE – Internet Key Exchange
IKE (v1/v2) is used for establishing Security Associations (SAs) between two endpoints.
Key Phases:
- Phase 1: Establishes a secure IKE SA (authentication + encryption)
- Phase 2: Negotiates IPSec SAs (AH or ESP parameters)
🛡️ Security Associations (SAs)
- A Security Association (SA) defines the encryption and authentication methods between two peers.
- Each direction (inbound/outbound) has its own SA.
- Identified by:
- SPI (Security Parameter Index)
- Destination IP
- Protocol (AH or ESP)
📘 Summary Table
| Protocol | Layer | Purpose | Common Use Cases |
|---|---|---|---|
| TCP | 4 | Reliable, connection-based | Web, email, file transfer |
| UDP | 4 | Fast, connectionless | DNS, VoIP, video/gaming |
| IPMC | 3 | One-to-many communication | IPTV, streaming, conferencing |
| IPSec | 3 | Secure IP communication | VPNs, secure tunnels |
| AH | 3 | Integrity and authentication | Data origin authentication |
| ESP | 3 | Encryption + authentication | VPN encryption |
| IKE | — | SA negotiation | IPSec VPN setup |
🧠 Pro Tip: IPSec works at the IP level, making it transparent to applications—ideal for VPNs and site-to-site tunnels.