Network Layer Protocols

Network layer protocols provide essential services for addressing, routing, diagnostics, and multicast communication in IP-based networks.

Protocol

Description

Use Case

ICMPv4 (Internet Control Message Protocol v4)

Provides diagnostics and error messages in IPv4 networks. Used for ping, traceroute, and network diagnostics.

Troubleshooting, path discovery

ICMPv6 (Internet Control Message Protocol v6)

IPv6 equivalent of ICMPv4 with extended features. Handles Neighbor Discovery, Path MTU, and IPv6 errors.

IPv6 diagnostics, auto-configuration

IGMP (Internet Group Management Protocol)

Manages multicast group membership for IPv4 hosts. Enables efficient multicast traffic delivery.

IPTV, streaming, conferencing

ARP (Address Resolution Protocol)

Resolves IPv4 addresses to MAC addresses within LAN. Essential for local packet delivery.

Local delivery in IPv4 networks

LOOP (Loopback Protocol)

Routes traffic back to the local host (127.0.0.1 / ::1). Used in local testing and IPC.

Application testing and diagnostics

IPv4 (Internet Protocol version 4)

Core IP protocol with 32-bit addressing. Most widely deployed IP version.

Internet and enterprise routing, legacy networks

IPv6 (Internet Protocol version 6)

Next‑generation IP with 128‑bit addressing, built‑in security, and multicast. Designed for future‑proof routing and addressing.

IoT, modern Internet, dual‑stack deployments

RFC: RFC 792

Main Features:

  • Echo request/reply for reachability checks

  • Error reporting for unreachable hosts and TTL expiry

  • Used by traceroute and Path MTU discovery

Use Cases:

  • Ping and route analysis

  • Diagnosing unreachable endpoints and latency issues

Alternative Protocols:

  • ICMPv6 – For IPv6 diagnostics

  • SNMP – Device and service monitoring

  • TCP Keepalive – Application-level reachability

Let us learn more about ICMPv4:

Jump to “ICMPv4”

RFC: RFC 4443

Main Features:

  • Supports IPv6 Neighbor Discovery and path discovery

  • Router and prefix advertisement/reductions and redirects

  • Error messaging for IPv6 operations

Use Cases:

  • IPv6 host reachability testing

  • Auto-configuration and router discovery

  • Path and route debugging for IPv6

Alternative Protocols:

  • ICMPv4 – IPv4 equivalent

  • SNMP – Network health monitoring

Let us learn more about ICMPv6:

Jump to “ICMPv6”

RFCs: RFC 2236 (v2), RFC 3376 (v3)

Main Features:

  • Enables IPv4 hosts to join/leave multicast groups

  • Controls multicast traffic delivery on LANs

  • Works with multicast routers to manage flows

Use Cases:

  • IPTV streaming

  • LAN conference and gaming multicast

  • Multicast-aware routing

Alternative Protocols:

  • MLD – IPv6 multicast protocol

  • PIM – Protocol‑Independent Multicast for routing

Let us learn more about IGMP:

Jump to “IGMP”

RFC: RFC 826

Main Features:

  • Resolves IPv4 addresses into MAC addresses via LAN broadcast

  • Maintains ARP cache for efficient forwarding

  • Operates at Layer 2 for Layer 3 traffic delivery

Use Cases:

  • Mapping IPv4 to MAC addresses on Ethernet

  • Required by routers and hosts for LAN communication

Alternative Protocols:

  • NDP – IPv6’s ARP equivalent

  • Proxy or static ARP – For subnet bridging or manual mapping

Let us learn more about ARP:

Jump to “ARP”

RFCs: RFC 1122 (IPv4), RFC 4291 (IPv6)

Main Features:

  • Returns traffic to local host using loopback addresses

  • Enables internal testing and IPC without external networking

Use Cases:

  • Testing local servers and applications

  • Verifying internal TCP/IP stack operation

Alternative Protocols:

  • UNIX domain sockets

  • Virtualized private loop interfaces

Let us learn more about LOOP:

Jump to “LOOP”

RFC: RFC 791

Main Features:

  • 32-bit addressing (IPv4)

  • Connectionless, best-effort packet delivery

  • Handles fragmentation, TTL, and checksums

  • Backbone of TCP/UDP traffic worldwide

Use Cases:

  • Global internet and LAN routing

  • Legacy device support and embedded systems

Alternative Protocols:

  • IPv6 – Next-generation protocol

  • IPX, ATM/Frame Relay – Older legacy alternatives

Let us learn more about IPv4:

Jump to “IPv4”

RFC: RFC 8200

Main Features:

  • 128-bit addressing for scalable IP

  • Simplified headers and built-in IPsec

  • Multi‑ and anycast support

  • Uses IPv6 Neighbor Discovery instead of ARP

Use Cases:

  • Modern internet infrastructure and IoT

  • Dual-stack networks

  • Secure routing and auto-configuration

Alternative Protocols:

  • IPv4 – Still in widespread use

  • 6LoWPAN – IPv6 on constrained IoT networks

Let us learn more about IPv6:

Jump to “IPv6”