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Chapter 3
ROUTING IP
Chapter 3: ROUTING IP
CHAPTER INTRODUCTION
 Understand the function of a router.
 Understand the structure of a routing table.
 Choose between static or dynamic routing on your
network.
 Select, install, and configure the dynamic routing
protocol most suitable for your network.
 Use routers to connect LANs and WANs.
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UNDERSTANDING IP ROUTING
 Routers direct data through the network.
 Routers connect two networks or two segments on
an internetwork.
 Routers can be used on LANs to provide connectivity
between segments, on WANs to provide connectivity
between LANs, and on either to provide connectivity
to the Internet.
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ROUTER FUNCTIONS
 Has a minimum of two network interfaces
 Holds a table of network information that it uses to
make routing decisions
 Can be either a hardware device or a software
application
Chapter 3: ROUTING IP
ROUTING LAN TRAFFIC
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Chapter 3: ROUTING IP
WAN ROUTING
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Chapter 3: ROUTING IP
CHOOSING A WAN TOPOLOGY
 Mesh
 Ring
 Star
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MESH TOPOLOGY
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RING TOPOLOGY
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STAR TOPOLOGY
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SELECTING A WAN TECHNOLOGY
 Leased Lines
 More expensive than dial on demand
 Guaranteed always-on service
 Dial on Demand
 Generally less expensive
 Pay for what you use
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USING LEASED LINES
 Permanent, always-on connection
 Expensive to install and run
 Can only be used to connect to a specified location
 Normally provided as a managed service by a
communications company
Chapter 3: ROUTING IP
USING DIAL-ON-DEMAND CONNECTIONS
 Includes ISDN, modem
 Links only used when necessary
 Normally charged on a usage basis
 Less expensive than leased-line installations
 Can be used to connect to more than one location
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Chapter 3: ROUTING IP
USING FRAME RELAY
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Chapter 3: ROUTING IP
USING VIRTUAL PRIVATE NETWORKS
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Chapter 3: ROUTING IP
ROUTING IP MULTICAST TRAFFIC
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USING NETWORK SWITCHES
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Chapter 3: ROUTING IP
SWITCHES, ROUTERS, AND
PERFORMANCE
 Switches are more expensive than hubs.
 Switches are less expensive than routers.
 Switches provide excellent performance
improvements over hub-based networks.
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Chapter 3: ROUTING IP
COMBINING ROUTING AND SWITCHING
 A switch reduces collisions but does not create a
broadcast domain.
 Implementation of VLANs allows creation of
broadcast domains.
 Ability to create a VLAN depends on the switch.
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Chapter 3: ROUTING IP
SELECTING ROUTERS AND SWITCHES
 Software based
 Places processing overhead on host server
 Allows functionality to be added or removed easily
 Hardware based
 Generally faster and more reliable than software
based routers
 More difficult to add or remove features
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Chapter 3: ROUTING IP
UNDERSTANDING ROUTING TABLES
 The routing table contains a listing for each route
including:
 Network Address
 NetMask
 Gateway Address
 Interface
 Metric
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STATIC VERSUS DYNAMIC ROUTING
Static routing
 An administrator manually enters information into
the routing table, using a program designed for that
purpose.
Dynamic routing
 The router receives routing table information
automatically from other routers, using a
specialized routing protocol.
Chapter 3: ROUTING IP
USING STATIC ROUTING
 Requires routes to be configured manually
 Route.exe command line utility
 Routing and Remote Access MMC snap-in
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USING DYNAMIC ROUTING
 Specialized routing protocols communicate
information between routers.
 Self-maintaining.
 Requires no intervention in the event of a topology
change.
Chapter 3: ROUTING IP
SELECTING A ROUTING PROTOCOL
 Distance vector routing protocols
 Less administration
 Better suited to smaller networks
 Link state routing protocols
 Require more administration
 More effective in larger networks
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DISTANCE VECTOR ROUTING
 Uses simple hop count to determine route to take
across the network
 1 router = 1 hop
 Doesn’t necessarily indicate the best or fastest route
Chapter 3: ROUTING IP
LINK STATE ROUTING
 Uses complex algorithms to determine preferred
route
 The number of hops between the router and the
destination
 The transmission speed of the links connecting the
router to the destination
 Delays caused by network traffic congestion
 A route cost value, supplied by an administrator
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UNDERSTANDING ROUTING PROTOCOL
COMMUNICATIONS
 Distance vector
 Each router transmits information about every router it
knows about to every other router on the network.
 Information is retransmitted periodically irrespective
of any change in the network topology.
 Link state
 After initial discovery, only changes are transmitted.
 Information is only transmitted to neighboring routers.
Chapter 3: ROUTING IP
ADMINISTERING ROUTING PROTOCOLS
 Distance vector
 Minimal configuration
 Minimal ongoing administration
 Link state
 Potentially complex configuration
 Minimal ongoing administration
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USING ROUTING AND REMOTE ACCESS
 RRAS
 Service in Windows 2003
 Configured via the Routing and Remote Access MMC
snap-in
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CHAPTER SUMMARY
 Routers enable communication between networks.
 Routers can take the form of software or hardware.
 A WAN topology defines the pattern of connections
among your network sites.
 Multicasting allows you to send data to a group of
machines using a single IP address.
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CHAPTER SUMMARY (continued)
 Static routing describes the manual creation of
routing table entries.
 Dynamic routing uses specialized routing protocols
to update changes in the network topology.
 RRAS can be used on Windows Server 2003
systems to configure static and dynamic routing.