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ARP and NDP

·439 words·3 mins
lab1918
Author
lab1918

ARP (Address Resolution Protocol) and NDP (Neighbor Discovery Protocol) are both protocols used for discovering physical addresses (like MAC addresses) associated with a given IP address on a network. However, they are used in different contexts and have distinct functionalities. Here’s a brief overview of how each works and how they differ:

ARP (Address Resolution Protocol)
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  • Used in IPv4 Networks: ARP is used in IPv4 networks to map an IPv4 address to a physical MAC address.
  • Operation: When a device wants to communicate with another device on the same network, it uses ARP to find out the MAC address corresponding to the target’s IP address.
  • Process:
    • The device sends an ARP request packet to the network’s broadcast address. This packet contains the IP address for which it needs the MAC address.
    • All devices on the local network segment receive the ARP request. The device with the matching IP address responds with an ARP reply, providing its MAC address.
    • The requesting device receives this MAC address and can then establish a connection.

NDP (Neighbor Discovery Protocol)
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  • Used in IPv6 Networks: NDP is used in IPv6 networks and is a part of the ICMPv6 protocol suite. It performs several functions that ARP does along with other IPv6 specific functionalities.
  • Functions: NDP is responsible for address autoconfiguration, address resolution, router discovery, and neighbor unreachability detection, among other things.
  • Process:
    • NDP uses ICMPv6 messages (like Neighbor Solicitation and Neighbor Advertisement messages) instead of broadcast ARP requests.
    • A Neighbor Solicitation message is used to discover the MAC address of a device on the same local network, similar to an ARP request in IPv4.
    • The device with the corresponding IPv6 address replies with a Neighbor Advertisement message containing its MAC address.

Key Differences
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  1. Protocol Used:

    • ARP is specific to IPv4.
    • NDP is used in IPv6 and is part of ICMPv6.

  2. Functional Scope:

    • ARP’s primary function is to map IPv4 addresses to MAC addresses.
    • NDP not only replaces ARP in IPv6 for address resolution but also handles other functions like router discovery and address autoconfiguration.

  3. Method of Communication:

    • ARP uses broadcast requests, which can lead to more network traffic on a busy network.
    • NDP uses ICMPv6 messages and multicast addresses, which is more efficient in terms of network traffic.

  4. Security Features:

    • ARP does not have built-in security features and is susceptible to attacks like ARP spoofing.
    • NDP can be secured with IPsec, providing better security features.

In summary, while ARP and NDP perform similar roles in their respective IP versions (IPv4 for ARP and IPv6 for NDP), NDP encompasses a broader set of functionalities and is designed to be more efficient and secure.