Lecture 9: Address Resolution for IPv4 and IPv6

Overview

• Module 9 of Cisco NetAcad Introduction to Networks
• Focus on address resolution in networking, specifically for IPv4 and IPv6

Address Types

• MAC Address: Layer 2, used for NIC to NIC communication on the same Ethernet network
• IP Address: Layer 3, logical address used for sending packets between source and destination devices

Key Concepts

• Layer 2 MAC Address: Delivers frames within the same network
• Layer 3 IP Address: Sends packets across multiple networks

Address Resolution Protocol (ARP) - IPv4

• Used to associate an IPv4 address with a MAC address on a device
• Functions:
  • Resolves IPv4 addresses to MAC addresses
  • Maintains ARP table mapping IPv4 to MAC
• ARP Table: Stores mappings of IPv4 addresses to MAC addresses
  • Searches the table for destination address within the same network or the default gateway for different networks
  • Sends ARP request if no entry is found
  • Entries are removed after a cache timer expiration or manually by administrator

IPv6 Neighbor Discovery (ND)

• Uses ICMPv6 for address resolution, not ARP
• ICMPv6 Messages:
  • Neighbor Solicitation (NS): Requests MAC address for a known IPv6 address
  • Neighbor Advertisement (NA): Response containing the requested MAC address
• Functions:
  • Provides address resolution, router discovery, and redirection

Address Resolution in IPv6

• Uses special Ethernet and IPv6 multicast addresses
• Neighbor Discovery replaces ARP in IPv6

Security Considerations

• ARP Vulnerabilities:
  • Broadcasts may lead to network congestion
  • ARP spoofing can lead to ARP poisoning attacks
• Mitigations: Enterprise switches employ techniques to protect against ARP attacks

Tools and Commands

• Cisco Devices: show ip arp to display ARP table
• Windows PCs: arp -a to view ARP entries

Practical Application

• Recommended to use Cisco NetAcad packet tracer labs for hands-on practice

Conclusion

• IPv4 uses ARP for MAC-IP association; IPv6 uses ICMPv6 ND
• Understanding these protocols is crucial for network communication

Additional Resources

• Links to video demonstrations and packet tracer labs provided in lecture

• For further questions, engage in the comment sections of the videos
• Check the YouTube channel for previous and future lectures.
• End of lecture.