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ARP, IPv4, IPv6, Neighbour Solicitation

Nov 16, 2024

Module 9: Address Resolution

Instructor: Professor Don LaFond

Lecture Overview

  • Focuses on ARP (Address Resolution Protocol) and Neighbor Discovery (ND).
  • Discusses roles of MAC and IP addresses.
  • Explains how ARP and ND enable network communications.

Key Concepts

Address Types

  • Layer 2 Physical Address (MAC Address):

    • Used for NIC-to-NIC communication on the same Ethernet network.
    • Example: PC1 (AAAA) to PC2 (5555).

  • Layer 3 Logical Address (IP Address):

    • Used for sending packets from a source to a destination on a different network.
    • Example: Host to web server communication.

ARP (Address Resolution Protocol)

  • Purpose: Resolves IPv4 addresses to MAC addresses.
  • Functions:
    • Resolves addressing to MAC addresses.
    • Maintains an ARP table mapping IPv4 to MAC addresses.
  • Process:
    • Device broadcasts to identify the destination's MAC address using an IP address.
    • Uses ARP requests and receives ARP replies.
    • If no entry, broadcasts ARP request for resolution.

Neighbor Discovery (ND) for IPv6

  • Uses ICMPv6: Instead of ARP, IPv6 employs ND with ICMPv6.
  • Messages:
    • Neighbor Solicitation (NS) and Neighbor Advertisement (NA) for address resolution.
    • Router Solicitation and Advertisement for router discovery.
    • Redirect messages for better next-hop selection.
  • Process:
    • Similar to ARP, uses multicast addresses for NS, reducing unnecessary processing.
    • Devices map IPv6 to a multicast MAC address.

Videos and Demonstrations

  • ARP Request and Reply:
    • PCA sends ARP request to determine MAC of PCC.
    • ARP request broadcast understood by all, reply unicast back to requester.
  • IPv6 Address Resolution:
    • Host uses NS to find destination MAC.
    • Packet placed on hold until MAC is resolved.

Security Considerations

  • ARP Spoofing and Poisoning:
    • Threat actors can spoof ARP replies leading to man-in-the-middle attacks.
    • Enterprise switches should implement mitigation techniques.

Practical Exercises

  • Packet Tracer Labs:
    • Examining ARP tables and simulating network communications.
    • Understanding neighbor discovery in IPv6.

Final Notes

  • Recommended to re-watch videos for better understanding.
  • Participation in forums for questions and discussions is encouraged.
  • External resources available (e.g., itexamanswers.net).

This session was led by Professor Don LaFond as part of the Cisco One curriculum on Module 9, focused on Address Resolution. Further questions can be addressed in forums or through comments on recorded sessions. Have a great learning experience!

Full transcript