M13: The ARP Process

Module 13 CISCO Networking: The ARP Process

Address Resolution

The device must discover the MAC address when it only knows the IP address of another device on the same LAN.

2 Key Addresses on Every LAN Device

1. MAC address (Layer 2 - Physical)

2. IP address (Layer 3 - Logical)

MAC Address

Layer 2 - Physical. Used for NIC‑to‑NIC communication on the same Ethernet network. Required to deliver the Ethernet frame.

IP Address

Layer 3 – Logical. Used to deliver the IP packet from source to destination. Destination may be local (same network) or remote (different network).

Address Resolution Protocol

Used when a device needs the MAC address associated with an IPv4 address on the same link. For IPv4

Neigbor Discovery

Performs the same role as ARP. Uses ICMPv6 messages instead of broadcasts. It is used to determine the MAC address of a known destination device IPv6 address.

Protocol Data Unit

What the data is called at a specific layer.
It’s the formal name for the chunk of data used at each layer of the OSI or TCP/IP model. Ex: for OSI Layer 7: PDU name is Data, While in Layer 4 Transport, PDU name is Segment (TCP) / Datagram (UDP)

Router

Its function is to interconnect different IP networks.