JUNOS Enterprise Routing

How to Use This Book

Let’s look at some specifics on how this book can help you. We’ll talk about what we cover in the various chapters, how the book is laid out, and some resources to help you along the way. To start, let’s discuss what you should know before you begin to read this book.

We are assuming a certain level of knowledge on the reader’s part. This is important because we are assuming you to be conversant in the following topic areas:

OSI model

The Open Systems Interconnection (OSI) model defines seven different layers of technology: Physical, Data Link, Network, Transport, Session, Presentation, and Application. This model allows network engineers and network vendors to easily discuss and apply technology to a specific OSI level. This segmentation lets engineers divide the overall problem of getting one application to talk to another into discrete parts and more manageable sections. Each level has certain attributes that describe it and each level interacts with its neighboring levels in a very well-defined manner.

Switches

These devices operate at Layer 2 of the OSI model and use logical local addressing to move frames across a network. Devices in this category include Ethernet, Asynchronous Transfer Mode (ATM), and Frame Relay switches.

Routers

These devices operate at Layer 3 of the OSI model and connect IP subnets to each other. Routers move packets across a network in a hop-by-hop fashion.

Ethernet

These broadcast domains connect multiple hosts together on a common infrastructure. Hosts communicate with each other using Layer 2 media access control (MAC) addresses.

Point-to-point links

These network segments are often thought of as WAN links in that they do not contain any end users. Often, these links are used to connect routers together in disparate geographical areas. Possible encapsulations used on these links include ATM, Frame Relay, Point-to-Point Protocol (PPP), and High-Level Data Link Control (HDLC).

IP addressing and subnetting

Hosts using IP to communicate with each other use 32-bit addresses. Humans often use a dotted decimal format to represent this address. This address notation includes a network portion and a host portion, which is normally displayed as 192.168.1.1/24.

TCP and UDP

These Layer 4 protocols define methods for communicating between hosts. The Transmission Control Protocol (TCP) provides for connection-oriented communications, whereas the User Datagram Protocol (UDP) uses a connectionless paradigm. Other benefits of using TCP include flow control, windowing/buffering, and explicit acknowledgments.

ICMP

Network engineers use this protocol to troubleshoot and operate a network as it is the core protocol used by the ping and traceroute (on some platforms) programs. In addition, the Internet Control Message Protocol (ICMP) is used to signal error and other messages between hosts in an IP-based network.

JUNOS CLI

The command-line interface (CLI) used by Juniper Networks routers, which is the primary method for configuring, managing, and troubleshooting the router. JUNOS documentation covers the CLI in detail, and it is freely available on the Juniper Networks web site (http://www.juniper.net).