June 2011
Beginner
264 pages
5h 16m
English
Content preview from Packet Guide to Core Network Protocols
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Chapter 4. Address Resolution Protocol
“The world is a jungle in general, and the networking game contributes many animals.”
—RFC 826
The operation of an IPv4 network requires the use of several different kinds of addresses at different layers of the networking model, but also the resolution of these addresses to one another. This chapter describes the address resolution process, gives real-world examples of the messaging used, and provides insight into potential security risks associated with its use.
The Problem
A vast majority of IP packet-based data transmission begins and ends on a LAN. This is true regardless of whether the IP packet is going to a neighbor on the same LAN or to the other side of the world. Chapter 3 describes how IP packets are encapsulated in LAN frames that use Layer-2 MAC addressing for both the source and the destination nodes. The source MAC address is easy to determine. The problem is the determination of the destination MAC address.
With Ethernet as a LAN infrastructure, a frame is constructed using the sender’s own address as the source at Layer 2 and IP address as the source at Layer 3. The destination IP address (or at least the name) is usually known, leaving only the determination of the destination MAC address. Figure 4-1 is a packet-capture review of these addresses shown in an encapsulated ICMP message.
Figure 4-1. Addressing layers
This is an example ...
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