4. ARP: Address Resolution Protocol

4.1. Introduction

We have seen that the IP protocol is designed to provide interoperability of packet switching across a large variety of physical network types. Doing so requires, among other things, converting between the addresses used by the network-layer software and those interpreted by the underlying network hardware. Generally, network interface hardware has one primary hardware address (e.g., a 48-bit value for an Ethernet or 802.11 wireless interface). Frames exchanged by the hardware must be addressed to the correct interface using the correct hardware addresses; otherwise, no data can be transferred. But a conventional IPv4 network works with its own addresses: 32-bit IPv4 addresses. Knowing a host’s ...

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