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(ebook pdf) - Cisco-CCIE-Fundamentals-Network-Design
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for ccies,this is very nice book for those who wanna go deep
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About This Manual xix
About This Manual
Document Objectives
This publication provides internetworking design and implementation information and helps you
identify and implement practical internetworking strategies that are both flexible and scalable.
This publication was developed to assist professionals preparing for Cisco Certified Internetwork
Expert (CCIE) candidacy, though it is a valuable resource for all internetworking professionals. It is
designed for use in conjunction with other Cisco manuals or as a standalone reference. You may find
it helpful to refer to the Cisco CCIE Fundamentals: Case Studies, which provides case studies and
examples of the network design strategies described in this book.
Audience
This publication is intended to support the network administrator who designs and implements
router- or switched-based internetworks.
Readers will better understand the material in this publication if they are familiar with networking
terminology. The Cisco Internetworking Terms and Acronyms publication is a useful reference for
those with minimal knowledge of networking terms.
Document Organization
This manual contains three parts, which are described below:
Part I, “Overview,” provides an introduction to the type of internetworking design topics that will be
discussed in this publication.
Part II, “Design Concepts,” provides detailed information about each of the design strategies and
technologies contained in this publication.
Part III, “Appedixes,” contains reference material.
Document Conventions
In this publication, the following conventions are used:
• Commands and keywords are in boldface.
• New, important terms are italicized when accompanied by a definition or discussion of the term.
• Protocol names are italicized at their first use in each chapter.
Document Conventions
xx
Cisco CCIE Fundamentals: Network Design
Note Means reader take note. Notes contain helpful suggestions or references to materials not
contained in this manual.
CHAPTER
Introduction 1-1
1
Introduction
Internetworking—the communication between two or more networks—encompasses every aspect
of connecting computers together. Internetworks have grown to support vastly disparate
end-system communication requirements. An internetwork requires many protocols and features to
permit scalability and manageability without constant manual intervention. Large internetworks can
consist of the following three distinct components:
• Campus networks, which consist of locally connected users in a building or group of buildings
• Wide-area networks (WANs), which connect campuses together
• Remote connections, which link branch offices and single users (mobile users and/or
telecommuters) to a local campus or the Internet
Figure 1-1 provides an example of a typical enterprise internetwork.
Figure 1-1 Example of a typical enterprise internetwork.
Designing an internetwork can be a challenging task. To design reliable, scalable internetworks,
network designers must realize that each of the three major components of an internetwork have
distinct design requirements. An internetwork that consists of only 50 meshed routing nodes can
pose complex problems that lead to unpredictable results. Attempting to optimize internetworks that
feature thousands of nodes can pose even more complex problems.
Switch
Switch
WAN
Switch
LAN
Site 2
LAN
Site 1
WAN
WAN
CampusCampus
Host A
Host B
Router A Router B
Designing Campus Networks
Cisco CCIE Fundamentals: Network Design
1-2
Despite improvements in equipment performance and media capabilities, internetwork design is
becoming more difficult. The trend is toward increasingly complex environments involving multiple
media, multiple protocols, and interconnection to networks outside any single organization’s
dominion of control. Carefully designing internetworks can reduce the hardships associated with
growth as a networking environment evolves.
This chapter provides an overview of the technologies available today to design internetworks.
Discussions are divided into the following general topics:
• Designing Campus Networks
• Designing WANs
• Utilizing Remote Connection Design
• Providing Integrated Solutions
• Determining Your Internetworking Requirements
Designing Campus Networks
A campus is a building or group of buildings all connected into one enterprise network that consists
of many local area networks (LANs). A campus is generally a portion of a company (or the whole
company) constrained to a fixed geographic area, as shown in Figure 1-2.
Figure 1-2 Example of a campus network.
The distinct characteristic of a campus environment is that the company that owns the campus
network usually owns the physical wires deployed in the campus. The campus network topology is
primarily LAN technology connecting all the end systems within the building. Campus networks
generally use LAN technologies, such as Ethernet, Token Ring, Fiber Distributed Data Interface
(FDDI), Fast Ethernet, Gigabit Ethernet, and Asynchronous Transfer Mode (ATM).
Token
Ring
Switch
WAN
Building A
Building B
Building C
Token
Ring
Router
Router
Router
Introduction 1-3
Trends in Campus Design
A large campus with groups of buildings can also use WAN technology to connect the buildings.
Although the wiring and protocols of a campus might be based on WAN technology, they do not
share the WAN constraint of the high cost of bandwidth. After the wire is installed, bandwidth is
inexpensive because the company owns the wires and there is no recurring cost to a service provider.
However, upgrading the physical wiring can be expensive.
Consequently, network designers generally deploy a campus design that is optimized for the fastest
functional architecture that runs on existing physical wire. They might also upgrade wiring to meet
the requirements of emerging applications. For example, higher-speed technologies, such as Fast
Ethernet, Gigabit Ethernet, and ATM as a backbone architecture, and Layer 2 switching provide
dedicated bandwidth to the desktop.
Trends in Campus Design
In the past, network designers had only a limited number of hardware options—routers or
hubs—when purchasing a technology for their campus networks. Consequently, it was rare to make
a hardware design mistake. Hubs were for wiring closets and routers were for the data center or main
telecommunications operations.
Recently, local-area networking has been revolutionized by the exploding use of LAN switching at
Layer 2 (the data link layer) to increase performance and to provide more bandwidth to meet new
data networking applications. LAN switches provide this performance benefit by increasing
bandwidth and throughput for workgroups and local servers. Network designers are deploying LAN
switches out toward the network’s edge in wiring closets. As Figure 1-3 shows, these switches are
usually installed to replace shared concentrator hubs and give higher bandwidth connections to the
end user.
Figure 1-3 Example of trends in campus design.
Layer 3 networking is required in the network to interconnect the switched workgroups and to
provide services that include security, quality of service (QoS), and traffic management. Routing
integrates these switched networks, and provides the security, stability, and control needed to build
functional and scalable networks.
ATM campus
switch
Cisco router
Shared hub
Multilayer switch
(Layers 2 and 3)
LAN switch (Layer 2)
Hub
CDDI/FDDI
concentrator
Shared hub
The new backbone
The new wiring closet
Traditional backbone
Traditional wiring closet
Cisco router
Si
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