© Copyright 2008 Course Outsource. All Rights Reserved.1
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT
Cisco Certified Entry Networking Technician
CCIP, CCIE, CCDA, CCDP, CCENT, CCNP, CCNA, CCVO, VLANDirector, TrafficDirector, CiscoWorks 2000, ONS 15454 Secure PIX Firewall, Secure Virtual Private Networks, Cisco, Cisco Systems, Cisco Systems Logo, Catalyst, EtherChannel, IOS and LightStream are registered trademarks of Cisco Systems, Inc. or its affiliates in the US and certain other countries.
© Copyright 2008 Course Outsource. All Rights Reserved. 2
© Copyright 2008 Course Outsource. All Rights Reserved.
IntroductionIntroduction
This is a 5 day hands-on course which covers the following exam objectives.
ICND1 (640-822)
Other CCNA exams:ICND2 (640-816)CCNA (640-802)
© Copyright 2008 Course Outsource. All Rights Reserved. 3
© Copyright 2008 Course Outsource. All Rights Reserved.
Cisco offers several options as a stepping stone approach to CCIE certification:
CCNP: Routing/SwitchingCCSP: SecurityCCVP: Voice/TelephonyCCIE: R/S, Security, Voice, Storage,
Service Provider
Cisco Professional Certifications
Service provider and Storage networking CCIE also exist, but do not have lower level certifications
© Copyright 2008 Course Outsource. All Rights Reserved. 4
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT (ICND1) 1.0 ExamCCENT (ICND1) 1.0 Exam
• Around 56 items• Around 804 out of 1000 to pass• The amount of questions and percent to pass
could vary on each exam• About 90 minutes• Cannot return to questions• Simulation, Test-let, Sim-let, multiple choice,
fill-in-the-blank, and drag n’ drop questions
© Copyright 2008 Course Outsource. All Rights Reserved. 5
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT Course OutlineCCENT Course Outline
Chapter 1: Internetworking
- History of Networking- Define Internetworking- Internetworking terms- Internetworking devices- Security Threats- OSI Reference Model- Ethernet Networking
Chapter 2: Introduction to TCP/IP- TCP/IP Protocol Stack
* TCP, UDP, IP, ICMP, ARP, RARP, Proxy ARP- IP addressing- Class C Subnetting
© Copyright 2008 Course Outsource. All Rights Reserved. 6
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT Course OutlineCCENT Course Outline
Chapter 3: The Cisco Router and Switch Interface- Cisco IOS- Cisco CLI- Administrative Functions- Configuring Interfaces- Introduction to Cisco Catalyst Switches
Chapter 4: Managing a Cisco Internetwork- Copying and saving the IOS and configuration- Dynamic Host Configuration Protocol- Domain Name System- Troubleshooting Cisco networks
© Copyright 2008 Course Outsource. All Rights Reserved. 7
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT Course OutlineCCENT Course Outline
Chapter 5: IP Routing - Basic IP routing- Static Routing- RIPv1 and RIPv2
Chapter 6: VLSM and Summarization- VLSM design and implementation
- Discontiguous Networks
- Summarization
© Copyright 2008 Course Outsource. All Rights Reserved. 8
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT Course OutlineCCENT Course Outline
Chapter 7: Network Address Translation- Static NAT
- Dynamic NAT Pools
- Port Address Translation (PAT)
Chapter 8: VLANs and STP- Virtual LANs (VLANs)
- Spanning Tree Protocol (STP)
© Copyright 2008 Course Outsource. All Rights Reserved. 9
© Copyright 2008 Course Outsource. All Rights Reserved.
CCENT Course OutlineCCENT Course Outline
Chapter 9: Wireless LANs- 802.11
- Basic Service Sets (BSS)
Chapter 10: Cisco WAN Support
- Basic WAN
- HDLC
- PPP
- Frame Relay
Chapter 11: Secure Device Manager
- Overview
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
PrefacePreface
Course Conventions
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2006 Course Outsource. All Rights Reserved. © Copyright 2008 Course Outsource. All Rights Reserved.
LocalLocal--Area and WideArea and Wide--Area Area Network Symbols KeyNetwork Symbols Key
Router Bridge Ethernet SwitchATM Switch
Hub MAUConcentrator Server
Comm Server CSU/DSUWAN Cloud
Serial LinesEthernet
Modem
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2006 Course Outsource. All Rights Reserved. © Copyright 2008 Course Outsource. All Rights Reserved.
Syntax ConventionsSyntax Conventions
Router prompts are in BLACK as follows:
R1#
Router commands to be entered by the user are in GREEN as follows:
R1(config)# interface serial 0R1(config-if)# shutdown
© Copyright 2008 Course Outsource. All Rights Reserved. 13
© Copyright 2008 Course Outsource. All Rights Reserved.
InternetworkingInternetworking
Chapter 1
Welcome to the exciting world of internetworking. This first chapter will really help you understand the basics of internetworking by focusing on how to connect networks together using Cisco routers and switches. To get all that down, you’ll first need to know exactly what an internetwork is, right? You create an internetwork when you take two or more LANs or WANs and connect them via a router, and configure a logical network addressing scheme with a protocol like IP.
© Copyright 2008 Course Outsource. All Rights Reserved. 14
© Copyright 2008 Course Outsource. All Rights Reserved.
Network EvolutionNetwork Evolution
• 1960s and 1970s - United States Department of Defense
(DOD) performed research. The Defense Advanced Research
Project Agency (DARPA) was the group performing the
research. The outcome was ARPANET which later became the
Internet. Mainly centered around a mainframe with
unintelligent terminals communicating with the host.
• 1970s and 1980s - Introduction of PCs. Local-area-
networks (LANs) grew primarily to decrease costs. DEC VAX
systems and DECnet were common. Wide-area-networks
(WANs) started to evolve.
• 1980s and 1990s - Networks have become a way of life
when performing daily tasks. Internetworks put together
LANs and WANs. Internetworks give an organization a
competitive advantage.
© Copyright 2008 Course Outsource. All Rights Reserved. 15
© Copyright 2008 Course Outsource. All Rights Reserved.
Network EvolutionNetwork Evolution
• 1990s -Users are placing increasing demands on the network.
Current and future networks are providing for integration of
voice, data and video. Client/server model placing increasing
demands on the network.
• 2000+ - Computer networks and the Internet are crucial to
the success of most every business. Wireless networks have
become commonplace. Speeds (data rates) are ever
increasing.
© Copyright 2008 Course Outsource. All Rights Reserved. 16
© Copyright 2008 Course Outsource. All Rights Reserved.
The Basic NetworkThe Basic Network
The basic network allows devices to share informationThe term “Computer Language” refers to Binary code (0’s or 1’s)
The reason that networks were even created is so that we can easily share information and files. Before networks, we had to use floppy disks or other type of physical media to share files.
Before Local Area Networks (LANs), we used mainframes from IBM, Honeywell, DEC, and others. The first LANs used coax connectivity but distance and amount of hosts that could be on a network were limited.
On a basic network, hardware addresses (MAC addresses) are usedto communicate between the hosts.
Hosts communicate with a language referred to as binary code – which is 0’s and 1’s.
© Copyright 2008 Course Outsource. All Rights Reserved. 17
© Copyright 2008 Course Outsource. All Rights Reserved.
The Basic InternetworkThe Basic Internetwork
A router creates an internetwork
In a basic network, hosts use hardware addresses to communicate between each host on the LAN. However, in an internetwork, hosts use logical addresses (IP addresses) to communicate with hosts on a different LAN (other side of the router).
Each connection into a router is a different logical network (broadcast domain).
A network is a connected collection of devices and end systems, such as computers and servers, which can communicate with each other.Networks carry data in many types of environments, including homes, small businesses, and large enterprises. Large enterprises may have various parts such as a Main Office, Remote Locations and BranchOffices along with Home Offices and Mobile Users.
© Copyright 2008 Course Outsource. All Rights Reserved. 18
© Copyright 2008 Course Outsource. All Rights Reserved.
Routing ProtocolsRouting Protocols
When you have more then one router, a routing protocol is used to share network information between the routers. Examples of routing protocols are RIP, RIPv2, IGRP, EIGRP and OSPF.
Routing protocols are used to tell neighbor routers about networks that they are not directly connected to. The routers place these networks in their routing table (map of the internetwork)
Examples of routing protocols are RIP, RIPv2, IGRP, EIGRP and OSPF. EIGRP is a Cisco proprietary routing protocol and is the preferred routing protocol for most networks. You only have Cisco routers in your internetwork, right?
Once all the routers have converged (all have the same routing table), then a routed protocol (typically and hopefully just IP) can send packets through the internetwork.
In smaller networks, you can create static routes instead of using a routing protocol. However, EIGRP works well in small and large networks, so why go through the hassle of static routes? (except for maybe a default route to the Internet).
© Copyright 2008 Course Outsource. All Rights Reserved. 19
© Copyright 2008 Course Outsource. All Rights Reserved.
Internetworking TermsInternetworking Terms
• Collision Domain• Network segment with multiple hosts in which they
all share the same bandwidth. If two hosts transmit
at the same time a collision occurs. Typically
created by using hubs in the network.
• Broadcast Domain• Boundary in which all devices see and participate in
broadcasts sent from hosts and servers. Broadcast
domains created by routers.
By default, switches break up collision domains. This is an Ethernet term used to describe a network scenario wherein one particular device sends a packet on a network segment, forcing every other device on that same segment to pay attention to it. At the same time, a different device tries to transmit, leading to a collision, after which both devices must retransmit, one at a time. Not good—very inefficient! This situation is typically found in a hub environment where each host segment connects to a hub that represents only one collision domain and only one broadcast domain. By contrast, each and every port on a switch represents its own collision domain.
Routers, by default, break up a broadcast domain, which is the set of all devices on a network segment that hear all broadcasts sent on that segment. Breaking up a broadcast domain is important because when a host or server sends a network broadcast, every device on the network must read and process that broadcast—unless you’ve got a router.
Switches create separate collision domains, but a single broadcast domain. Routers provide a separate broadcast domain.
© Copyright 2008 Course Outsource. All Rights Reserved. 20
© Copyright 2008 Course Outsource. All Rights Reserved.
Common Network ComponentsCommon Network Components
Devices used in an internetwork:PC: Computers serve as end pointsInterconnections: i.e. Network Interface Cards (NICs)Hub: Multiple port repeaterBridge: Segments network with hardware addressesSwitch: Multiport bridge with more intelligenceRouter: Segments networks with logical addresses (i.e. IP)
This next section will cover the various Internetworking devices.
© Copyright 2008 Course Outsource. All Rights Reserved. 21
© Copyright 2008 Course Outsource. All Rights Reserved.
MultiMulti--Port Repeater (Hub)Port Repeater (Hub)
One collision domainOne broadcast domain
A hub is really a multiple-port repeater. A repeater receives a digital signal and reamplifies or regenerates that signal, and then forwards the digital signal out all active ports without looking at any data. An active hub does the same thing. Any digital signal received from a segment on a hub port is regenerated or reamplified and transmitted out all ports on the hub. This means all devices plugged into a hub are in the same collision domain as well as in the same broadcast domain.
© Copyright 2008 Course Outsource. All Rights Reserved. 22
© Copyright 2008 Course Outsource. All Rights Reserved.
Transparent BridgesTransparent Bridges
One broadcast domain
Collision domains
Bridges reduce collisions within a broadcast domain while increasing the number of collision domains
Bridge
Bridges and switches read each frame as it passes through the network. The layer-2 device then puts the source hardware address in a filter table and keeps track of which port the frame was received on. This information (logged in the bridge’s or switch’s filter table) is what helps the machine determine the location of the specific sending device.
© Copyright 2008 Course Outsource. All Rights Reserved. 23
© Copyright 2008 Course Outsource. All Rights Reserved.
MultiMulti--Port Bridge (Switch)Port Bridge (Switch)
One broadcast domain
Each port is a separate collision domain
The term bridging was introduced before routers and hubs were implemented, so it’s pretty common to hear people referring to bridges as “switches.”That’s because bridges and switches basically do the same thing—break up collision domains on a LAN. After a filter table is built on the layer-2 device, it will only forward frames to the segment where the destination hardware address is located. If the destination device is on the same segment as the frame, the layer-2 device will block the frame from going to any other segments.If the destination is on a different segment, the frame can only be transmitted to that segment. This is called transparent bridging.
© Copyright 2008 Course Outsource. All Rights Reserved. 24
© Copyright 2008 Course Outsource. All Rights Reserved.
RouterRouter
WAN Services
Each interface is a separate collision domain and broadcast domain
S0/0
E0
E1
Fa0
Here are some points about routers:Routers, by default, will not forward any broadcast or multicast packets.Routers use the logical address in a Network layer header to determine the next hop router to forward the packet to.Routers can use access lists, created by an administrator, to control security on the types of packets that are allowed to enter or exit an interface.Routers can provide layer-2 bridging functions if needed and can simultaneously route through the same interface.Layer-3 devices (routers in this case) provide connections between virtual LANs (VLANs).Routers can provide quality of service (QoS) for specific types of network traffic.
© Copyright 2008 Course Outsource. All Rights Reserved. 25
© Copyright 2008 Course Outsource. All Rights Reserved.
Impact of Applications on the NetworkImpact of Applications on the Network
•Batch Applications•TFTP, FTP•Bandwidth important but not critical•No direct human interaction
•Interactive Applications•Human to Machine Interaction•Inventory Inquiries, Database Updates
•Real-Time Applications•VoIP, Video•Mission Critical Applications (end to end latency critical)•Human to Human Interaction
When considering the interaction between the network and applications that ran on the network, bandwidth was historically the main concern. Batch applications such as FTP, TFTP, and inventory updates would be initiated by a user, then run to completion by the software with no further direct human interaction. Like interactive applications, real time applications such as VoIP and video applications involve human interaction. Because of the amount of information that is transmitted, bandwidth has become critical. In addition, because these applications are time-critical, latency (delay through the network) has become critical. Even variations in the amount of latency can affect the network. Not only is proper bandwidth mandatory, QoS is mandatory. VoIP and video applications must be given the highest priority.
© Copyright 2008 Course Outsource. All Rights Reserved. 26
© Copyright 2008 Course Outsource. All Rights Reserved.
Characteristics of a NetworkCharacteristics of a Network
• Speed• Cost• Security• Availability• Scalability• Reliability• Topology
Speed: Speed is a measure of how fast data is transmitted over the network. Another term to describe speed is data rate.Cost: Cost indicates the general cost of components, installation, and maintenance of the network.Security: Security indicates how secure the network is, including the data that is transmitted over the network. Availability: Availability is a measure of the probability that the network will be available for use when it is required. Scalability: Scalability indicates how well the network can accommodate moreusers and data transmission requirements. If a network is designed and optimized for just the current requirements, it can be very expensive and difficult to meet new needs when the network grows.Reliability: Reliability indicates the dependability of the components (routers, switches, PCs, and so on) that make up the network. This is often measured as a probability of failure, or mean time between failures (MTBF).Topology: In networks, there are two types of topologies: the physical topology, which is the arrangement of the cable, network devices, and end systems (PCs and servers), and the logical topology, which is the path that the data signals take through the physical topology.
© Copyright 2008 Course Outsource. All Rights Reserved. 27
© Copyright 2008 Course Outsource. All Rights Reserved.
Collision and Broadcast DomainsCollision and Broadcast Domains
How many broadcast domains are shown?
How many collision domains are shown?
Two collision domains, two broadcast domains.
A router breaks up both collision domains and broadcast domains and a hub breaks up no collision domains.
© Copyright 2008 Course Outsource. All Rights Reserved. 28
© Copyright 2008 Course Outsource. All Rights Reserved.
How many collision domains are shown?
How many broadcast domains are shown?
Collision and Broadcast DomainsCollision and Broadcast Domains
Hub HubHub HubHub Hub
Switch Switch
One broadcast domain, six collision domains are shown.
By default, switches break up collision domains with each port, but are one broadcast domain by default.
© Copyright 2008 Course Outsource. All Rights Reserved. 29
© Copyright 2008 Course Outsource. All Rights Reserved.
Which of the hosts can transmit simultaneously without causing collisions?
Collision and Broadcast DomainsCollision and Broadcast Domains
How many collision and broadcast domains are show?
HubSwitch
Only the hosts connected to the switch can transmit simultaneously without causing collisions.
Four collision domains are shown, one broadcast domain. By default, switches break up collision domains with each port, but they are only one broadcast domain by default.
© Copyright 2008 Course Outsource. All Rights Reserved. 30
© Copyright 2008 Course Outsource. All Rights Reserved.
Hardware and Logical AddressingHardware and Logical Addressing
Communicate on LAN via hardware addresses
Communicate on LAN via hardware addresses
Communicate via logical address
Hardware AddressUniquely identifies a host on a LAN
Logical AddressUniquely identifies a host on an internetwork
© Copyright 2008 Course Outsource. All Rights Reserved. 31
© Copyright 2008 Course Outsource. All Rights Reserved.
Physical TypologiesPhysical Typologies
•Bus: In early networks, computers and other network devices were cabled together in a line using coaxial cable. Modern bus topologies connect the host devices to the bus using twisted-pair wiring.•Ring: Computers and other network devices are cabled together, with the last device connected to the first to form a circle, or ring. This category includes both ring and dual-ring topologies. The physical connection can be made using either coaxial or fiber.•Star: A central cabling device (i.e. switch) connects the computers and other network devices. The physical connection is commonly made using twisted-pair wiring. Most prevalent in today’s networks.•Mesh: There are both full-mesh and partial mesh topologies. In a full-mesh topology each node is connected to every other node for redundancy.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Common Threats to Physical Common Threats to Physical InstallationsInstallations
• Hardware threats
• Environmental threats
• Electrical threats
• Maintenance threats
What should be part of a comprehensive network security plan?*Physically secure network equipment from potential access by unauthorized individuals.
Hardware threats: The threat of physical damage to the router or switch hardware. Mission-critical network equipment should be located in locked room with restricted access.Environmental threats: Threats such as temperature extremes (too hot or too cold) or humidity extremes (too wet or too dry). The room should have dependable temperature and humidity control systems. If possible, remotely monitor and alarm the environmental parameters of the room. Electrical threats: Threats such as voltage spikes, insufficient supply voltage
(brownouts), unconditioned power (noise), and total power loss. Electrical supply problems can be limited by installing uninterruptible power supply (UPS) or backup generator.:Maintenance threats: Maintenance threats include poor handling of equipment (ESD), lack of spares, poor cabling. Clearly label all equipment cabling and secure the cabling to equipment racks to prevent accidental damage, disconnection, or incorrect termination. Do not leave a console connected to and logged into any console port. Always log off administrative interfaces when leaving a station.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Need for Network SecurityNeed for Network Security
• Closed Network – No outside connectivity, networks
designed in this way can be considered safe from
outside attacks. However, internal threats still exist.
• Open Network - Corporate networks require access
to the Internet and other public networks. It is not
uncommon for corporate networks have several access
points to public and other private networks. Securing
open networks is extremely important. Open networks
have not only internal threats but external threats as
well.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Balancing Network SecurityBalancing Network Security
• There is a huge challenge of balancing network
security needs against e-business needs, legal
issues, and government policies.
• The overall security challenge is to find a balance
between two important needs: open networks to
support evolving business requirements and
freedom-of-information initiatives, versus
protection of private, personal, and strategic
business information.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Common AttackCommon Attack
• Denial of Service (DoS): a flood of packets
that are requesting a TCP connection to a
server
company.com
Bad Guy
Internet
65,000 timesSY N
SY NSY N
ACKACK
…CRASH!
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Security AppliancesSecurity Appliances• IDS
An intrusion detection system is used to detect several types of
malicious behaviors that can compromise the security and trust of a
computer system. This includes network attacks against vulnerable
services, data driven attacks on applications, host based attacks such
as privilege escalation, unauthorized logins and access to sensitive
files, and malware (viruses, trojan horses and worms).
• IPSAn intrusion prevention system is a computer security device that
monitors network and/or system activities for malicious or unwanted
behavior and can react, in real-time, to block or prevent those
activities. Network-based IPS, for example, will operate in-line to
monitor all network traffic for malicious code or attacks. When an
attack is detected, it can drop the offending packets while still
allowing all other traffic to pass.
© Copyright 2008 Course Outsource. All Rights Reserved. 37
© Copyright 2008 Course Outsource. All Rights Reserved.
The OSI Reference ModelThe OSI Reference Model
(OSI) Open System Interconnection
was created by the
(ISO) International Organization for
Standardization
The OSI reference model was created in the late 1970s, and the main reason the International Organization for Standardization (ISO) released the OSI model was so different vendor networks could work (communicate) with each other. One of the greatest functions of the OSI specifications is to assist in data transfer between disparate hosts, meaning, they enable us to transfer data between a Unix host and a PC or a Mac, for example.The OSI isn’t a physical model, though. Rather, it’s a set of guidelines that application developers can use to create and implement applications that run on a network. It also provides a framework for creating and implementing networking standards, devices, and internetworking schemes.
© Copyright 2008 Course Outsource. All Rights Reserved. 38
© Copyright 2008 Course Outsource. All Rights Reserved.
ISOISOISO is the Greek term for “equal”
• Why the OSI?• It divides the network communication process into smaller
and simpler components, thus aiding component development, design, and troubleshooting
• Changes in the OSI model at one layer do not affect other
layers
• It encourages industry standardization by defining what
functions occur at each layer of the model
Macintosh Unix PC IBM
Advantages of using the OSI layered model include, but are not limited to, the following:Allows multiple-vendor development through standardization of network componentsAllows various types of network hardware and software to communicatePrevents changes in one layer from affecting other layers, so it does not hamper development
© Copyright 2008 Course Outsource. All Rights Reserved. 39
© Copyright 2008 Course Outsource. All Rights Reserved.
File, print, message, database, and application services
End to end connectionRouting
Framing
Physical Topology
Data Translation
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI Layer & FunctionsOSI Layer & Functions
Dialog control (Maintains, tracks, and closes sessions between applications.)
Concerned with host-to-host communication
Concerned with local and physical network
765
43
21
The OSI reference model has seven layers:Application layerPresentation layerSession layerTransport layerNetwork layerData Link layerPhysical layer
© Copyright 2008 Course Outsource. All Rights Reserved. 40
© Copyright 2008 Course Outsource. All Rights Reserved.
OSI Model (Rational)OSI Model (Rational)
Application
Presentation
Session
Transport
Network
Data Link
Physical
• Manageable• Standardizes interfaces• Ensures interoperability• Promotes modular engineering• Reduces development cycle• Simplifies teaching
Early network development was chaotic. The early 1980s saw tremendous increases in the number and sizes of networks. By the mid-1980s, companies began to experience difficulties from all of the expansions they had made. It became more difficult for networks using different specifications and implementations to communicate with one another. To address the problem of networks being incompatible and unable to communicate with one another, the International Organization forStandardization (ISO) researched different network schemes. As a result of this research, the ISO created a model that would help vendors create networks that would be compatible with, and operate with, other networks, hence the OSI reference model.The OSI reference model was released in 1984. It provided vendors with a set of standards that ensured greater compatibility and interoperability between the various types of network technologies produced by companies around the world. The OSI model is considered the best tool available for teaching people about data networks.
© Copyright 2008 Course Outsource. All Rights Reserved. 41
© Copyright 2008 Course Outsource. All Rights Reserved.
OSI Model (Remembering)OSI Model (Remembering)
Application
Presentation
Session
Transport
Network
Data Link
Physical
Easy way to remember the order of the OSI reference model:All People Seem To Need Data Processing.Or in the reverse order:Please Do Not Teach Sales People Anything. ☺Translates to:
Sentences to help remember the layers of the OSI Reference Model:
Please Do Not Throw Sausage Pizza Away.
Or
All People Seem To Need Data Processing.
© Copyright 2008 Course Outsource. All Rights Reserved. 42
© Copyright 2008 Course Outsource. All Rights Reserved.
Application LayerApplication Layer
Application
Presentation
Session
Transport
Network
Data Link
Physical
Remote LoginTelnet, rlogin
File TransferTFTP, FTP
EmailSimple Mail Transfer Protocol (SMTP)
Network Management SNMP
Internet BrowsingHTTP, HTTPS
Closest to the user. Provides services directly to applications. Does not provide any services to other OSI layers
Name ManagementDNS
The Application layer of the OSI model marks the spot where users actually communicate to the computer. This layer is responsible for identifying and establishing the availability of the intended communication partner, and determining if sufficient resources for the intended communication exist.
A vast array of protocols combine at the DoD model’s Process/Application layer to integrate the various activities and duties spanning the focus of the OSI’s corresponding top three layers (Application, Presentation, and Session).
© Copyright 2008 Course Outsource. All Rights Reserved. 43
© Copyright 2008 Course Outsource. All Rights Reserved.
Presentation LayerPresentation Layer
Application
PresentationSession
Transport
Network
Data Link
Physical
Rich Text Format
MPEG files
Musical Instrument Digital Interface
Quick Time Movies
Provides for code formatting, conversion and representation. Ensures that information sent by the application layer of one system is readable by another. Can include encryption services.
JPEG files
The Presentation layer gets its name from its purpose: It presents data to the Application layer and is responsible for data translation and code formatting.This layer is essentially a translator and provides coding and conversion functions. A successful data-transfer technique is to adapt the data into a standard format before transmission.
© Copyright 2008 Course Outsource. All Rights Reserved. 44
© Copyright 2008 Course Outsource. All Rights Reserved.
Session LayerSession Layer
Application
Presentation
SessionTransport
Network
Data Link
Physical
XWindow
Remote Procedure Call (RPC)
Network File System (NFS)
Structured Query Language (SQL)
Establishes, manages and terminates sessions between applications. Coordinates service requests and responses when applications communicate between different hosts. Responsible for inter-host communication.
The Session layer is responsible for setting up, managing, and then tearing down sessions between Presentation layer entities. This layer also provides dialogue control between devices, or nodes.
© Copyright 2008 Course Outsource. All Rights Reserved. 45
© Copyright 2008 Course Outsource. All Rights Reserved.
Transport LayerTransport Layer
Establishes a reliable communication stream between a pair of systems. Responsible for end-to-end communications. Deals with issues such as reliable service and flow control.
Application
Presentation
Session
Transport
Network
Data Link
Physical
Provides mechanisms for the establishment, maintenance, and termination of virtual circuits.
User Datagram Protocol (UDP)
Transmission Control Protocol (TCP)
The Transport layer segments and reassembles data into a data stream. Services located in the Transport layer both segment and reassemble data from upper-layer applications and unite it onto the same data stream. They provide end-to-end data transport services and can establish a logical connection between the sending host and destination host on an internetwork.Provides mechanisms for the establishment, maintenance, and termination of virtual circuits. The Transport layer can use positive acknowledgement and retransmission to ensure reliable delivery.Information flow control. The Transport Layer sends Segments between peer transport layers.
© Copyright 2008 Course Outsource. All Rights Reserved. 46
© Copyright 2008 Course Outsource. All Rights Reserved.
Network LayerNetwork Layer
Establishes the connection between two end nodes and provides path selection. This is where routing takes place.
Application
Presentation
Session
Transport
NetworkData Link
Physical
PDU: Packet
TCP/IP Suite•IP – Internet Protocol•ICMP – Internet Control Message
Protocol•ARP – Address Resolution Protocol•RARP – Reverse Address Resolution
Protocol
The Network layer (also called layer 3) manages devices addressing, tracks the location of devices on the network, and determines the best way to move data, which means that the Network layer must transport traffic between devices that aren’t locally attached. Routers (layer-3 devices) are specified at the Network layer and provide the routing services within an internetwork.
Device addressingTracks locations of devices on the networkDetermines the best way to move data
PDU at the Network layer is called “Packet”.
The Network layer sends Packets between peer network layers.
© Copyright 2008 Course Outsource. All Rights Reserved. 47
© Copyright 2008 Course Outsource. All Rights Reserved.
Data Link LayerData Link Layer
Provides transport of data across a physical link. Specifies topology and hardware (physical) addressing.
Application
Presentation
Session
Network
Transport
Data LinkPhysical
Ethernet
Frame Relay
HDLC
PPP
The Data Link layer provides the physical transmission of the data and handles error notification, network topology, and flow control.
This means the Data Link layer will ensure that messages are delivered to the proper device on a LAN using hardware addresses, and translates messages from the Network layer into bits for the Physical layer to transmit.
The Data Link layer sends Frames between peer data link layers.
© Copyright 2008 Course Outsource. All Rights Reserved. 48
© Copyright 2008 Course Outsource. All Rights Reserved.
Logical Link Control (LLC)
Media access control (MAC)
802.2802.3802.11
IEEE Data Link SubIEEE Data Link Sub--LayersLayers
PDU: Frame
The IEEE has divided this layer into two sub-layers:The MAC sublayerThe LLC sublayer
The IEEE Ethernet Data Link layer has two sublayers:
Media Access Control (MAC) 802.3This defines how packets are placed on the media. Contention media access is “first come/first served” access where everyone shares the same bandwidth—hence the name. Physical addressing is defined here, as well as logical topologies.
Logical Link Control (LLC) 802.2This sublayer is responsible for identifying Network layer protocols and then encapsulating them. An LLC header tells the Data Link layer what to do with a packet once a frame is received.
PDU at the Data Link layer is called “Frame”.
© Copyright 2008 Course Outsource. All Rights Reserved. 49
© Copyright 2008 Course Outsource. All Rights Reserved.
MAC AddressMAC Address
MAC address is burned into ROM on a network interface card
0080.0c45. 6789
24 bits24 bits
Vendor CodeVendor Code Serial NumberSerial Number
0000.0c98.7654
E0: 0000.0c45.6789
S0
0080.0c45.6789
Unique for each local area interface48-bit addresses
Expressed as 12 hexadecimal digits0000.0c12.abcd
First six hexadecimal digits contain manufacturer identification(vendor code) also called Organizational Unique Identifier (OUI).Manufacturer IDs administered by IEEE
© Copyright 2008 Course Outsource. All Rights Reserved. 50
© Copyright 2008 Course Outsource. All Rights Reserved.
Physical LayerPhysical Layer
Application
Presentation
Session
Transport
Network
Data Link
Physical
Specifies electrical signaling and hardware interface. This includes voltage levels, data rates, maximum transmission distances and physical connectors
EIA/TIA-449
HSSI
EIA-530
V.35
Finally arriving at the bottom, we find that the Physical layerdoes two things: It sends bits and receives bits. Bits come only in values of 1 or 0—a Morse code with numerical values.
The physical layer defines the electrical, mechanical, procedural and functional specifications for:activatingmaintainingdeactivating
the physical link between end systems.
The Physical layer sends Bits between peer physical layers.
© Copyright 2008 Course Outsource. All Rights Reserved. 51
© Copyright 2008 Course Outsource. All Rights Reserved.
Peer to Peer CommunicationPeer to Peer Communication
Each layer of the OSI Model communicates with its peer layer.
Segments
Bits
Packets
Frames
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Each layer of the OSI model at the source must communicate with its peer layer at the destination. During the protocols ateach layer exchange packets of information called protocol data units (PDUs) between peer layers.
Bits are sent between physical layer peers.Frames are sent between data link layer peers.Packets are sent between transport layer peers.Segments are sent between transport layer peers.
© Copyright 2008 Course Outsource. All Rights Reserved. 52
© Copyright 2008 Course Outsource. All Rights Reserved.
TCP/IP Stack compared to OSI TCP/IP Stack compared to OSI
Application
Presentation
Session
Transport
Network
Data Link
Physical
Process/Application
Host to Host
Internet
NetworkAccess
The TCP/IP model is basically a condensed version of the OSI model—it’s composed of four, instead of seven, layers:
Process/Application layerTransport layerInternet layerNetwork Access layer
The OSI model and the TCP/IP stack were developed, by different organizations, at approximately the same time as a means to organize and communicate the components that guide the transmission of data.
© Copyright 2008 Course Outsource. All Rights Reserved. 53
© Copyright 2008 Course Outsource. All Rights Reserved.
Data EncapsulationData Encapsulation
Transport
Data Link
Physical
Network
Upper Layer Data
Upper Layer DataTCP Header
DataIP Header
DataLLC Header
0101110101001000010
DataMAC Header
Presentation
Application
Session
Segments
Packets
Bits
FramesFCS
Data
Following the data stream:Alphanumeric user input is converted to data for transmission on the network (At the upper layers)Data is converted to segments, which allow hosts to reliably communicate (At the Transport Layer)Segments are converted to packets or datagrams with a source and destination logical address (At the Network layer)Packets or datagrams are converted to frames for transmission over an interface to the network (At the Data Link Layer)Frames are converted to bits, and uses a synchronization and clocking function (At the Physical Layer)
When going from layer 7 to layer 1, encapsulation occursWhen going from layer 1 to layer 7, de-encapsulation occurs
© Copyright 2008 Course Outsource. All Rights Reserved. 54
© Copyright 2008 Course Outsource. All Rights Reserved.
Ethernet TechnologiesEthernet Technologies
Chapter 1 Continued
Ethernet is a contention media access method that allows all hosts on a network to share the same bandwidth of a link. Ethernet is popular because it’s readily scalable, meaning it’s comparatively easy to integrate new technologies, like FastEthernet and Gigabit Ethernet, into an existing network infrastructure. It’s also relatively simple to implement in the first place, and with it, troubleshooting is reasonably straightforward. Ethernet uses both Data Link and Physical layer specifications
© Copyright 2008 Course Outsource. All Rights Reserved. 55
© Copyright 2008 Course Outsource. All Rights Reserved.
Physical
MAC layerEt
hern
e t
100b
aseT
X
10B
aseT
IEEE 802.3
10B
ase5
10B
ase2
100b
aseF
X
802.3 Specifications for 10mb Ethernet
802.3u Specifications for 100mb FastEthernet
100b
aseT
4
10B
aseF
DIX Standard
LLC layer IEEE 802.2
1000
base
TX
1000
base
FX
1000
base
T4
802.3ab\z Specifications for 1000mb Gigabit Ethernet
IEEE 802.3 LANIEEE 802.3 LAN
Ethernet was first implemented by a group called DIX (Digital, Intel, and Xerox).They created and implemented the first Ethernet LAN specification, which the IEEE used to create the IEEE 802.3 Committee. This was a 10Mbps network that ran on coax, twisted-pair, and fiber physical media.The IEEE extended the 802.3 Committee to new committees known as 802.3U (FastEthernet) and 802.3aband 802.3z (Gigabit Ethernet) and 802.3ac (10-Gig). These are both specified on twisted-pair and fiber physical media.
© Copyright 2008 Course Outsource. All Rights Reserved. 56
© Copyright 2008 Course Outsource. All Rights Reserved.
Preamble7 Bytes
DA6 Bytes
SA6 Bytes
Ether-Type2 Bytes
Data46-1500
FCS4 Bytes
Ethernet_II
802.3_Ethernet (IEEE 802.3 RAW)
Preamble7 Bytes
DA6 Bytes
SA6 Bytes
Length2 Bytes
Data46-1500
FCS2 Bytes
Frame TypesFrame Types
SOF
SOF
Ethernet at the Data Link layer is responsible for Ethernet addressing, commonly referred to as hardware addressing or MAC addressing. Ethernet is also responsible for framing packets received from the Network layer and preparing them for transmission on the local network through the Ethernet contention media access method. There are four different types of Ethernet frames available:Ethernet_IIIEEE 802.3IEEE 802.2SNAP
The function of Ethernet stations is to pass data frames betweeneach other using a group of bits known as a MAC frame format.
This provides error detection from a cyclic redundancy check (CRC). But remember—this is error detection, not error correction.
© Copyright 2008 Course Outsource. All Rights Reserved. 57
© Copyright 2008 Course Outsource. All Rights Reserved.
802.3 with LLC (802.2)802.3 with LLC (802.2)
Dest SAP Source SAP802.2 Ctrl
Dest SAP
AA
Source SAP
AA
SNAPCtrl03
OUI ID
EtherType
802.3_EthernetDA6 Bytes
SA6 Bytes
LengthBytes
DATA FCS
Since the 802.3 Ethernet frame cannot by itself identify the upper-layer (Network) protocol, it obviously needs some help. The IEEE defined the 802.2 LLC specifications to provide this function and more.
802.2 uses Destination and Source Service Access Points (SAP’s) to identify the Network layer protocol
The SNAP frame has its own protocol field to identify the upper-layer protocol. This is really a way to allow an Ethernet_II Ether-Type field to be used in an 802.3 frame.
© Copyright 2008 Course Outsource. All Rights Reserved. 58
© Copyright 2008 Course Outsource. All Rights Reserved.
EthernetEthernet
Ethernet is a physical star, logical bus technology
Physical star topology means that the network is physically connected in the center
Physical star topology means that the network is physically connected in the center, as shown in the hub diagram in this slide.The logical bus means the signal must run from the beginning of a network segment to the end, and everyone on that segment must listen to the signal on the bus.Switches break up these segments into smaller logical bus’s
© Copyright 2008 Course Outsource. All Rights Reserved. 59
© Copyright 2008 Course Outsource. All Rights Reserved.
CSMA/CDCSMA/CD
• Carrier Sense, Multiple Access with Collision Detection (CSMA/CD)
• Statistical limit to the number of devices on segment
As devices increase:• Collisions increase• Effective bandwidth decreases (through-put)• Increased delay• Increased congestion
Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium. CSMA/CD was created to overcome the problem of those collisions that occur when packets are transmitted simultaneously from different nodes.
Used in Half-Duplex Ethernet networks.Half-duplex is single pair for both transmit and receive.If a collision does occur, the transmitting host sends an extended jam
signal, which tells all hosts to stop transmitting.Backoff algorithm is the retransmission delay that is enforced when a
collision occurs. This causes global synchronization which reduces performance.
© Copyright 2008 Course Outsource. All Rights Reserved. 60
© Copyright 2008 Course Outsource. All Rights Reserved.
Duplex OverviewDuplex OverviewDuplex Overview
802.3 Half duplex (CSMA/CD)Unidirectional data flowHigher potential for collisionHubs connectivity One wire pair Shared collision domainLower Effective Throughput
Hub
Full duplexPoint-to-point onlyAttached to dedicated switched portRequires full-duplex support on both endsCollision free Collision detect circuit disabledTwo wire pair
Half-duplex Ethernet is defined in the original 802.3 Ethernet and uses only one wire pair with a digital signal running in both directions on the wire.It also uses the CSMA/CD protocol to help prevent collisions and to permit
retransmitting if a collision does occur. If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions. Half-duplex Ethernet—typically 10BaseT—is only about 30 to 40 percent efficient as Cisco sees it, because a large 10BaseT network will usually only give you 3- to 4Mbps—at most.But full-duplex Ethernet uses two pairs of wires, instead of one wire pair like half duplex. And full duplex uses a point-to-point connection between the transmitter of the transmitting device and the receiver of the receiving device. This means that with full duplex data transfer, you get a faster data transfer compared to half-duplex. And because the transmitted data is sent on a different set of wires then the received data, no collisions will occur—sweet!
Full-Duplex is collision freeHalf-Duplex is subject to collisionsFull-Duplex provides higher throughput than Half-Duplex Ethernet of the
same bandwidthHalf-Duplex operates in a shared collision domainFull-Duplex operates in a private collision domain
© Copyright 2008 Course Outsource. All Rights Reserved. 61
© Copyright 2008 Course Outsource. All Rights Reserved.
Straight
Cisco DTE device(Ethernet 0)
12345678
12345678
Switch device(Ethernet Interface)
RJ-45 pinsEIA/TIA 568B
Pair 4
Pair 1Pair 1
Pair 3
Pair 4
Pair 3Pair 2
Pair 2
Pair 4
Pair 1Pair 1
Pair 3
Pair 4
Pair 3Pair 2
Pair 2
RJRJ--45 Wiring and CAT 5 Cables45 Wiring and CAT 5 Cables
This type of Ethernet cable is used to connect:-Host to switch or hub-Router to switch or hubFour wires are used in straight-through cable to connect Ethernet devices. It is relatively simple to create this type of cable.
© Copyright 2008 Course Outsource. All Rights Reserved. 62
© Copyright 2008 Course Outsource. All Rights Reserved.
RJRJ--45 Wiring and Cables45 Wiring and Cables
RJ-45 pinsEIA/TIA 568B
Cross over
Switch device(Ethernet Interface)
12345678
12345678
Switch device(Ethernet Interface)
Pair 4
Pair 1Pair 1
Pair 3
Pair 4
Pair 3Pair 2
Pair 2
Pair 4
Pair 1Pair 1
Pair 3
Pair 4
Pair 3Pair 2
Pair 2
Hub
This type of Ethernet cable can be used to connect:-Switch to switch-Hub to hub-Host to hostThe same four wires are used in this cable as in the straight-through cable, but we just connect different pins together.
© Copyright 2008 Course Outsource. All Rights Reserved. 63
© Copyright 2008 Course Outsource. All Rights Reserved.
Console CablesConsole Cables
PC or other DTE device (Com 1)
87654321
Rolled
TxDDTRRTS
GNDGND
CTSDSR/CDRxD
Cisco DTE device(Console)
RTSDTRTxDGNDGNDRxD
DSR/CDCTS
12345678
RJ-45 pinsand signals
Adapter
DB 9
Although this type isn’t used to connect any Ethernet connections together, you can use a rolled Ethernet cable to connect a host to a router console serial communication (com) port.If you have a Cisco router or switch, you would use this cable to connect your PC running HyperTerminal to the Cisco hardware. Eight wires are used in this cable to connect serial devices.
As you can see, Cisco console cables are rolled cables where pin 1 maps to pin 8, pin 2 maps to pin 7 and so on.
© Copyright 2008 Course Outsource. All Rights Reserved. 64
© Copyright 2008 Course Outsource. All Rights Reserved.
Chapter 1 LabChapter 1 Lab
Written Lab 1.1
Open your lab books and complete written lab 1.1
© Copyright 2008 Course Outsource. All Rights Reserved. 243
© Copyright 2008 Course Outsource. All Rights Reserved.
IP RoutingIP Routing
Chapter 5
In this chapter, we’re to discuss the IP routing process. This is an important subject to understand since it pertains to all routers and configurations that use IP. IP routing is the process of moving packets from one network to another network using routers. And by routers, we mean Cisco routers, of course!
This chapter correlates directly with chapter 5 of the SybexCCNA Study Guide.
© Copyright 2008 Course Outsource. All Rights Reserved. 244
© Copyright 2008 Course Outsource. All Rights Reserved.
To route a router need to know:• Remote Networks• Neighbor Routers• All Possible routes to remote network• The absolute best route to all remote
networks• Maintain and verify the routing information
What is Routing?What is Routing?
D C B A
Once you create an internetwork by connecting your WANs and LANs to a router, you then need to configure logical network addresses, such as IP addresses, to all hosts on the internetwork so that they can communicate across that internetwork.The term routing is used for taking a packet from one device and sending it through the network to another device on a different network. Routers don’t care about hosts—they only care about networks and the best path to each network. The logical network address of the destination host is used to get packets to a network through a routed network, then the hardwareaddress of the host is used to deliver the packet from a router to the correct destination host.
© Copyright 2008 Course Outsource. All Rights Reserved. 245
© Copyright 2008 Course Outsource. All Rights Reserved.
Basic Path SelectionBasic Path Selection
What interface will the router send out a packet if it has destination address of 10.10.10.18?
Fa0/0
Fa0/2
Fa0/1
S0/010.10.20.2 /24
10.10.10.2 /24
10.10.40.1 /24
10.10.30.1 /24
The router will packet switch the packet to the FastEthernet 0/0 interface and then frame it and send it out the LAN
© Copyright 2008 Course Outsource. All Rights Reserved. 246
© Copyright 2008 Course Outsource. All Rights Reserved.
Longest Match RuleLongest Match Rule
Ping Outgoing Interface
10.1.1.9
10.4.4.4
10.1.4.7
209.41.3.7
Routers will compare the destination ip address with entries in their route table and choose the path that provides the longest applicable match.
Assuming you want to ping the addresses as indicated in the table, through which interface will the packets be forwarded?
Route Outgoing Interface
10.0.0.0/8 E1
10.1.0.0/16 E0
10.1.4.0/24 E2
0.0.0.0/0 E3
E0
E1
E2
E3
Ping to 10.1.1.9 would be sent out of E0Ping to 10.4.4.4 would be sent out of E1Ping to 10.1.4.7 would be sent out of E2Ping to 209.41.3.7 would be sent out of E3
Don’t confuse this with Administrative Distance. Administrative Distance is how the best routes are selected for the route table.If there are multiple entries to the same network, the longest match rule always wins. Look at the prefix
© Copyright 2008 Course Outsource. All Rights Reserved. 247
© Copyright 2008 Course Outsource. All Rights Reserved.
Simple IP RoutingSimple IP Routing
172.16.1.0
BA
172.16.2.0
172.16.2.2
172.16.1.2172.16.2.1 172.16.1.1
e0 e0
>ping 172.16.1.2>ping 172.16.1.2
B
172.16.3.1 172.16.3.2
s0s0
Host A
Host B
The IP routing process is fairly simple and doesn’t change, regardless of the size of network you have. For an example, we’ll describe step by step what happens when Host A wants to communicate with Host B on a different network.In this example, a user on Host A pings Host B’s IP address.
© Copyright 2008 Course Outsource. All Rights Reserved. 248
© Copyright 2008 Course Outsource. All Rights Reserved.
show ip show ip arparp
What will Router1 do when it receives the above frame?
Router1# show ip arp
Protocol Address Age(min) Hardware Adddr Type Interface
Internet 192.168.10.2 9 0000.0c09.ff76 ARPA FastEthernet0/0Internet 192.168.30.9 8 0000.0c89.a400 ARPA FastEthernet0/1Internet 192.168.20.3 - 0000.0c67.ue29 ARPA FastEthernet0/0Internet 192.168.30.3 9 0000.0c00.142d ARPA FastEthernet0/2Internet 192.168.50.5 - 0000.0c35.11p8 ARPA FastEthernet0/1Internet 192.168.40.2 - 0000.0c36.ku57 ARPA FastEthernet0/2
0000.0c09.ff76 192.168.10.2 0000.0c67.ue29 192.168.30.3Source MAC Source IP Destination MAC Destination IPData Frame
Answer on next slide
© Copyright 2008 Course Outsource. All Rights Reserved. 249
© Copyright 2008 Course Outsource. All Rights Reserved.
Answer to Previous SlideAnswer to Previous Slide
0000.0c00.142d192.168.30.3
F0/2
F0/1
F0/0192.168.40.2
0000.0c36.ku57192.168.20.3
0000.0c67.ue29
192.168.10.20000.0c09.ff76
192.168.50.5
0000.0c89.a400192.168.30.9
0000.0c35.11p8
Dest Mac0000.0c00.142d
Source Mac0000.0c36.ku57
Dest Mac0000.0c67.ue29
Source Mac0000.0c09.ff76
Router1 will strip off the source MAC address and replace it with the MAC address 0000.0c36.6965Router1 will strip off the destination MAC address and replace it with the MAC address 0000.0c07.4320Router1 will forward the data packet out interface Fa0/2
© Copyright 2008 Course Outsource. All Rights Reserved. 250
© Copyright 2008 Course Outsource. All Rights Reserved.
Host A Web browses to the HTTP Host A Web browses to the HTTP ServerServer……..
3. The destination port number in a segment header will have a value of __
1. The destination address of a frame will be the _______________________
2. The destination IP address of a packet will be the IP addressof the ________________________________
A BS0
S1E0 E0
Host A HTTP Server
This slide represents how segments, packets and frames are used to send data from HostA to the HTTP server. It’s important to remember that frames are “ALWAYS” on a local network and hardware addressees are used.Packets are used to route a segment from one network to another networkSegments are used to rebuild a datastream on a remote host, in this case, the HTTP server.
3. The destination port number in a segment header will have a value of 80
1. The destination address of a frame will be the MAC address of the E0 interface of the Lab_A router
2. The destination IP address of a packet will be the IP addressof the network interface of the HTTP server
© Copyright 2008 Course Outsource. All Rights Reserved. 251
© Copyright 2008 Course Outsource. All Rights Reserved.
How will the frames sent from host A be How will the frames sent from host A be addressed when the frames reach host B?addressed when the frames reach host B?
192.168.23.100c0.6AE6.EAEF
Router
192.168.20.500c0.0c36.f892
192.168.23.200a0.3D3A.66BC
192.168.20.600a0.3C22.1122
A B
Final Frame received by Host BSource MAC = 00c0.0c36.f892Destination MAC = 00a0.3C22.1122Source IP = 192.168.23.2Destination IP – 192.168.20.6
Initial Frame sent by Host ASource MAC = 00a0.3d3a.66bcDestination MAC = 00c0.6ae6.eaefSource IP = 192.168.23.2Destination IP – 192.168.20.6
© Copyright 2008 Course Outsource. All Rights Reserved. 252
© Copyright 2008 Course Outsource. All Rights Reserved.
Host A is sending to Host BHost A is sending to Host B
How will Router1 handle the data received from Host A?
Router1# show ip arpProtocol Address Age(min) Hardware Adddr Type InterfaceInternet 192.168.10.2 9 0000.0c09.ff76 ARPA FastEthernet0/0Internet 192.168.30.9 8 0000.0c89.a400 ARPA FastEthernet0/1Internet 192.168.20.3 - 0000.0c67.ue29 ARPA FastEthernet0/0Internet 192.168.30.3 9 0000.0c00.142d ARPA FastEthernet0/2Internet 192.168.50.5 - 0000.0c35.11p8 ARPA FastEthernet0/1Internet 192.168.40.2 - 0000.0c36.ku57 ARPA FastEthernet0/2
Router 1
Switch 1
Switch 2
Switch 3Host A
192.68.10.2 Host B192.68.30.3
Host C192.68.50.5
Fa0/0
Fa0/2
Fa0/1
An ethernet frame will be sent out fa0/2 with a destination address of 0000.0c07.4320 since 192.168.40.5 is in Router1’s ARP table.
© Copyright 2008 Course Outsource. All Rights Reserved. 253
© Copyright 2008 Course Outsource. All Rights Reserved.
172.16.3.2
SO
Static RoutesStatic Routes
172.16.1.0
B172.16.3.1
A B
Stub Network
172.16.2.0
SOA
Routes must be unidirectional
Static routing occurs when you manually add routes in each router’s routing table. There are pros and cons to static routing, but that’s true for all routing processes.Things that are good about static routing:-No overhead on the router CPU-No bandwidth usage between routers-Security (because the administrator can only allow routing to certain networks)Things that aren’t so good about static routing:-The administrator must really understand the internetwork and how each router is connected super well in order to configure routes correctly.-If a network is added to the internetwork, the administrator has to add a route to it on all routers—by hand.-It just won’t work for you in large networks because maintaining it would be a full-time job in itself.
© Copyright 2008 Course Outsource. All Rights Reserved. 254
© Copyright 2008 Course Outsource. All Rights Reserved.
ip route 172.16.1.0 255.255.255.0 172.16.3.2orip route 172.16.1.0 255.255.255.0 s0
Static Route ExampleStatic Route Example
172.16.3.2
SO
172.16.1.0
B172.16.3.1
A B
Stub Network
172.16.2.0
SO
This slide shows an example of a simple static route command.
Static routes are used to send all unknown destination packets to a next hop router.
© Copyright 2008 Course Outsource. All Rights Reserved. 255
© Copyright 2008 Course Outsource. All Rights Reserved.
Default RoutesDefault Routes
172.16.3.2
SO
172.16.1.0
B172.16.3.1
A B
Stub Network
172.16.2.0
SO
ip route 0.0.0.0 0.0.0.0 172.16.3.1 ip classless
We use default routing to send packets with a remote destination network not in the routing table to the next-hop router. You can only use default routing on stub networks—those with only one exit port out of the network.
© Copyright 2008 Course Outsource. All Rights Reserved. 256
© Copyright 2008 Course Outsource. All Rights Reserved.
Default Route ExampleDefault Route Example
• ip route 0.0.0.0 0.0.0.0 172.16.3.2• ip route 0.0.0.0 0.0.0.0 s0
this works too….• ip default-network 172.16.3.0 (EIGRP)• default-information originate (OSPF)
172.16.3.2
S0
Internal Network
172.16.3.1Gateway
S0ISP
This slide shows multiple examples to configure default routes.
The “ip route 0.0.0.0 0.0.0.0 172.16.3.2” has an Administrative Distance of 1.The “ip route 0.0.0.0 0.0.0.0 s0” has an Administrative Distance of 0 just as a connected interface.
Administrative Distance will be discussed later.
© Copyright 2008 Course Outsource. All Rights Reserved. 257
© Copyright 2008 Course Outsource. All Rights Reserved.
Routing LoopsRouting Loops
172.16.3.2
SO
B172.16.3.1A B
SO
ip route 0.0.0.0 0.0.0.0 172.16.3.1 ip classless
ip route 0.0.0.0 0.0.0.0 172.16.3.2 ip classless
Be careful NOT create routing loops!
© Copyright 2008 Course Outsource. All Rights Reserved. 258
© Copyright 2008 Course Outsource. All Rights Reserved.
Larger Static Route ExampleLarger Static Route Example
config tip route 0.0.0.0 0.0.0.0 172.16.40.1ip classless
E0 E0
S1 S1S0
S0
S0
S0
config tip route 172.16.10.0 255.255.255.0 172.16.30.1ip route 172.16.20.0 255.255.255.0 172.16.30.1ip route 172.16.50.0 255.255.255.0 172.16.40.2
10
20
30
50
40
.1
.2
.1
This slide shows an example of using both static and default routing on a network with four router. Every router would need to have the routing tables built.
© Copyright 2008 Course Outsource. All Rights Reserved. 259
© Copyright 2008 Course Outsource. All Rights Reserved.
Chapter 5 LabChapter 5 Lab
Hands-on Lab 5.1
Open your lab books and perform hands-on lab 5.1.
© Copyright 2008 Course Outsource. All Rights Reserved. 260
© Copyright 2008 Course Outsource. All Rights Reserved.
Dynamic RoutingDynamic Routing
Chapter 5 Continued
Dynamic routing is when protocols are used to find and update routing tables on routers. True—this is easier than using static or default routing, but it’ll cost you in terms of router CPU processes and bandwidth on the network links. A routing protocol defines the set of rules used by a router when it communicates between neighbor routers.
© Copyright 2008 Course Outsource. All Rights Reserved. 261
© Copyright 2008 Course Outsource. All Rights Reserved.
• Routing protocols are used between routers to: • Determine the path of a packet through a network• Maintain routing tables• Examples?
• RIP, EIGRP, OSPF
• Routed protocols are:• Assigned to an interface• Once the path is determined by the Routing protocol, determines
method of delivery• Examples?
• IP, IPX
What is a Routing Protocol?
A routing protocol is used by routers to dynamically find all the networks in the internetwork and to ensure that all routers have the same routing table.Basically, a routing protocol determines the path of a packet
through an internetwork. Examples of routing protocols are RIP, IGRP, EIGRP and OSPF.
Okay—once all routers know about all networks, a routed protocol can be used to send user data (packets) through the established enterprise. Routed protocols are assigned to an interface and determine the method of packet delivery. Examples of routed protocols are IP and IPX.
© Copyright 2008 Course Outsource. All Rights Reserved. 262
© Copyright 2008 Course Outsource. All Rights Reserved.
Autonomous System 1 Autonomous System 2
IGPs: RIP, IGRPEIGRP, OSPF EGPs: BGP
Routing ProtocolsRouting Protocols
• An autonomous system is a collection of networks under a common administrative domain.
• IGPs operate within an autonomous system.• EGPs connect different autonomous systems.
There are two types of routing protocols used in internetworks: interior gateway protocols (IGPs) and exterior gateway protocols (EGPs).IGPs are used to exchange routing information with routers in the same autonomous system (AS). An AS is a collection of networks under a common administrative domain, which basically means that all routers sharing the same routing table information are in the same AS.EGPs are used to communicate between ASs. An example of an EGP is Border Gateway Protocol (BGP).
© Copyright 2008 Course Outsource. All Rights Reserved. 263
Classful routing means that all devices in the network must use the same subnet mask.
© Copyright 2008 Course Outsource. All Rights Reserved.
ClassfulClassful Routing OverviewRouting Overview
• Classful routing protocols do not include the subnet mask with the route advertisement.
• Within the same network, consistency of the subnet masks is assumed.
• Summary routes are exchanged between foreign networks.
• Examples of classful routing protocols:• RIP Version 1 (RIPv1)• IGRP
© Copyright 2008 Course Outsource. All Rights Reserved. 264
Prefix routing does send subnet mask information with the route updates. This is called classless routing.
© Copyright 2008 Course Outsource. All Rights Reserved.
Classless Routing OverviewClassless Routing Overview
• Classless routing protocols include the subnet mask with the route advertisement.
• Classless routing protocols support Variable-Length Subnet Masking (VLSM).
• Advantages of classless routing:• Fewer IP addresses are wasted• Summarization can be manually controlled
within the routing protocol• Examples of classless routing protocols:
• RIP Version 2 (RIPv2)• EIGRP• OSPF• IS-IS
© Copyright 2008 Course Outsource. All Rights Reserved. 265
© Copyright 2008 Course Outsource. All Rights Reserved.
Classes of Routing ProtocolsClasses of Routing Protocols
A
B
C
D
A
B
C
DDistance VectorHybrid Routing
Link State
There are three classes of routing protocols:Distance vector: The distance-vector protocols find the best path to a remote network by judging distance. Each time a packet goes through a router, that’s called a hop. The route with the least number of hops to the network is determined to be the best route. The vector indicates the direction to the remote network. Both RIP and IGRP are distance-vector routing protocols. They send the entire routing protocol to directly connected neighbors.Link state: In link-state protocols, also called shortest-path-first protocols, the routers each create three separate tables. One of these tables keeps track of directly attached neighbors, one determines the topology of the entire internetwork, and one is used as the routing table. Link-state routers know more about the internetwork than any distance-vector routing protocol. OSPF is an IP routing protocol that is completely link state. Link State protocols send updates containing the state of their own link to all other routers on the network. Hybrid: The hybrid protocols use aspects of both distance vector and link state—for example, EIGRP.
© Copyright 2008 Course Outsource. All Rights Reserved. 266
© Copyright 2008 Course Outsource. All Rights Reserved.
Routing Protocol Comparison ChartRouting Protocol Comparison Chart
This slide shows the various routing protocols available and their characteristics.
RIPv2 is exactly like RIPv1, except that it send out subnet maskinformation with the route table updates. This allows RIPv2 to support VLSM networks and discontiguous networks.
© Copyright 2008 Course Outsource. All Rights Reserved. 267
© Copyright 2008 Course Outsource. All Rights Reserved.
Administrative Distance: Administrative Distance: Ranking RoutesRanking Routes
Default Administrative Distance:Directly Connected: 0Static Route: 1RIP: 120IGRP: 100EIGRP: 90OSPF: 110
A
B
D
C
E
IGRP Administrative Distance = 100
RIP Administrative Distance = 120
I need to send data to Network
E. Routers B and C will get it there, but which
route is best?
The Administrative Distance (AD) is used to rate the trustworthiness of routing information received on a router from a neighbor router. An administrative distance is an integer from 0 to 255, where 0 is the most trusted and 255 means no traffic will be passed via this route.If a router receives two updates listing the same remote network, the first thing the router checks is the AD. If one of the advertised routes has a lower AD than the other, then the route with the lowest AD will be placed in the routing table.If both advertised routes to the same network have the same AD, then routing protocol metrics (such as hop count or bandwidth of the lines) will be used to find the best path to the remote network. The advertised route with the lowest metric will be placed in the routing table. But if both advertised routes have the same AD as well as the same metrics, then the routing protocol will load-balance to the remote network.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Distance Vector MetricsDistance Vector Metrics
• IP RIP uses only Hop count
• IGRP uses a composite metric of
bandwidth and delay of the line by
default. MTU, Reliability and Load can be
administratively configured
Metrics are used to determine the best path to a remote network if more then one path exists.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Distance VectorDistance VectorDistance Vector
CC BB AADD
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
Distance—How farVector—In which direction
Distance—How farVector—In which direction
• Routers pass periodic copies of their routing table to neighboring routers and accumulate distance vectors.
The distance-vector protocols find the best path to a remote network by judging distance.
Each time a packet goes through a router, that’s called a hop. With RIP, the route with the least number of hops to the network is determined to be the best route. IGRP utilizes a more complex algorithm for determining the best route. It is a combination of bandwidth, delay, load, reliability and mtu.
The vector indicates the direction to the remote network. Both RIP and IGRP are distance-vector routing protocols.
Distance vector routing protocols are sometimes referred to as routing by rumor.Distance vector algorithms do not allow a router to know the exact topology of an internetwork.This information is somewhat analogous to the information found on signs at a highway intersection. A sign points toward a road leading away from the intersection and indicates the distance to the destination.
Further down the highway, another sign also points toward the destination, but now the distance to the destination is shorter.
As long as each successive point on the path shows that the distance to the destination is successively shorter, the traffic is following the best path.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 00
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
Discovering RoutesDiscovering RoutesDiscovering Routes
Routers, when powered up and the interfaces are enabled, have only their directly connected networks in the routing table
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 00
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011
11172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.012 S1
S0S0S0
Discovering RoutesDiscovering RoutesDiscovering Routes
Router C is directly connected to network 172.16.4.0 with a distance of 0. Router A’s path to 172.16.4.0 is through Router B, with a hop count of 2.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Routing LoopsRouting LoopsRouting Loops
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 00
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011
11172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.012 S1
S0S0S0
XX
Router C has detected the failure of network 172.16.4.0 and stops routing packets out its E0 interface. However, Router A has not yet received notification of the failure and still believes it can access network 172.16.4.0 through Router B.
Router A’s routing table still reflects a path to network 10.4.0.0 with a distance of 2.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Symptom: Counting to InfinitySymptom: Counting to InfinitySymptom: Counting to Infinity
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.0E0E0 00
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 S0 22
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0E0
E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.0
11
33172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.014 S1
S0S0S0
XX
Because Router B’s routing table indicates a path to network 172.16.4.0, Router C believes it now has a viable path to 172.16.4.0 through Router B. Router C updates its routing table to reflect a path to network 172.16.4.0 with a hop count of 2.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Symptom: Counting to InfinitySymptom: Counting to InfinitySymptom: Counting to Infinity
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 33
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011
44172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.015 S1
S0S0S0
XX
Router A receives the new routing table from Router B, detects the modified distance vector to network 172.16.4.0, and recalculates its own distance vector to network 172.16.4.0
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Solution: Defining a MaximumSolution: Defining a MaximumSolution: Defining a Maximum
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 1616
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011 172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.01
16 S1S0S0
S0 1616
XX
To avoid prolonging the count-to-infinity time span, distance vector protocols define infinity as some maximum number.
This number refers to a routing metric, such as a hop count.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Solution: Split HorizonSolution: Split HorizonSolution: Split Horizon
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 00
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011
11172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.012 S1
S0S0S0
XX
Periodic Update
Network 4 not sent in update
The rule of Split Horizon states: Never advertise a route out of the interface through which you learned it.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Solution: Route PoisoningSolution: Route PoisoningSolution: Route Poisoning
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 1616
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011
1616172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.012 S1
S0S0S0
XX
Route Poisoning sends a “infinite hop count” for a downed link.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2008 Course Outsource. All Rights Reserved.
Solution: Poison ReverseSolution: Poison ReverseSolution: Poison Reverse
AA BB CC
172.16.1.0 172.16.2.0 172.16.3.0 172.16.4.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
172.16.2.0172.16.2.0
172.16.3.0172.16.3.000
00S0S1
Routing TableRouting Table
172.16.3.0172.16.3.0 S0 00
172.16.4.0172.16.4.0 E0 1616
Routing TableRouting Table
172.16.1.0172.16.1.0
172.16.2.0172.16.2.0E0S0
00
172.16.1.0172.16.1.0
172.16.4.0172.16.4.011
1616172.16.1.0172.16.1.0 S0 22
172.16.2.0172.16.2.0 S0 11172.16.3.0172.16.3.0
172.16.4.0172.16.4.01
16 S1S0S0
S0
XX
Poison Reverse is an acknowledgement to a route poison. Poison reverse overrides the split-horizon solution
Poison Reverse states: Once you learn of a route through an interface, advertise it as unreachable back through that same interface.
© Copyright 2008 Course Outsource. All Rights Reserved.
© Copyright 2006 Course Outsource. All Rights Reserved. © Copyright 2008 Course Outsource. All Rights Reserved.
• The router keeps an entry for the “possibly down state” in the network, allowing time for other routers to recompute for this topology change.
• Hold-down timers are used to prevent regular update messages from inappropriately reinstating a route that may have gone bad.
Holddown TimersHolddown Timers
A B C E0S0S1S0S0E0
10.1.1.1 10.2.1.1 10.3.1.1 10.4.1.1
Network 10.4.1.1 is Down….. Then Back Up……Then Back Down…..
Update After Hold Down Time
Update After Hold Down Time
Network 10.4.1.1 is unreachable
Hold-down timers are used to prevent regular update messages from inappropriately reinstating a route that may have gone bad.Hold-downs tell routers to hold any changes that might affect routes for some period of time. The hold-down period is usually calculated to be just greater than the period of time necessary to update the entire network with arouting change.
© Copyright 2008 Course Outsource. All Rights Reserved. 280
© Copyright 2008 Course Outsource. All Rights Reserved.
Chapter 5 ContinuedChapter 5 Continued
RIP Version 1 and
Version 2
© Copyright 2008 Course Outsource. All Rights Reserved. 281
© Copyright 2008 Course Outsource. All Rights Reserved.
64kbps
T1
T1 T1
• Hop count metric selects the path, 16 is unreachable
• Full route table broadcast every 30 seconds
• Load balance maximum of 6 equal cost paths (default = 4)
• RIPv2 supports VLSM and Discontiguous networks
RIP Overview
Routing Information Protocol (RIP) is a true distance-vector routing protocol. It sends the complete routing table out to allactive interfaces every 30 seconds. RIP only uses hop count to determine the best way to a remote network, but it has a maximum allowable hop count of 15 by default, meaning that 16 is deemed unreachable. RIP works well in small networks, but it’s inefficient on large networks with slow WAN links or on networks with a large number of routers installed.RIP version 1 uses only classful routing, which means that all devices in the network must use the same subnet mask.
© Copyright 2008 Course Outsource. All Rights Reserved. 282
© Copyright 2008 Course Outsource. All Rights Reserved.
Router(config)# router rip
Router(config-router)# network network-number*
network 172.16.0.0network 192.168.10.0
router ripnetwork 172.16.0.0network 10.0.0.0
router rip
*Network is a classful network address. Every device on network uses the same subnet mask
172.16.10.0 192.168.10.010.3.5.0
RIP Routing Configuration
To configure RIP routing, just turn on the protocol with the router rip command and tell the RIP routing protocol which networks to advertise. That’s it. Understand that RIP is configured with classful routing network addresses!
© Copyright 2008 Course Outsource. All Rights Reserved. 283
© Copyright 2008 Course Outsource. All Rights Reserved.
RIP Version 2RIP Version 2
• Allows the use of Variable Length Subnet Masks (VLSM) by sending subnet mask information with each route update
• Distance Vector – same AD, and timers.• Easy configuration, just add the command “version 2” under
the router rip configuration• Uses Multicast address 224.0.0.9 versus broadcast like RIP
version 1• RIPv2 allows routing update authentication
router ripnetwork 10.0.0.0version 2
Easy configuration, just add the command “version 2” under the router rip configuration.RIPv2 is the preferred choice over RIPv1 because it supports VLSM and discontiguous networks.
© Copyright 2008 Course Outsource. All Rights Reserved. 284
© Copyright 2008 Course Outsource. All Rights Reserved.
Discontiguous AddressingDiscontiguous Addressing
• Two networks of the same classful networks are separated
by a different network address
192.168.10.16/28
10.1.1.0/24
192.168.10.32/28
– RIPv1 and IGRP do not advertise subnet masks, and therefore cannot support discontiguous subnets.
– OSPF, EIGRP, and RIPv2 can advertise subnet masks, and therefore can support discontiguous subnets.
– To fix discontiguous networking, use the no auto-summary command
If you create VLSM network, sometimes you may find that the backbone connecting buildings together is a different class of network. This is called discontiguous addressing. By default routing protocols will not work across discontiguous networks. By using the “no auto-summary” command on the network boundaries, routing protocols will be able do work across a discontiguous addressed network.
© Copyright 2008 Course Outsource. All Rights Reserved. 285
© Copyright 2008 Course Outsource. All Rights Reserved.
Passive InterfacePassive Interface
Maybe you don’t want to send RIP updates out your router
interface connected to the Internet. Use the passive-
interface command:
Router(config)#router rip
Router(config-router)#passive-interface serial0
This allows a router to receive route updates on an interface, but not send updates via that interface
S0 GatewayInternet
UpdatesXX
You probably don’t want your RIP network advertised everywhere on your LAN and WAN—there’s not a whole lot to be gained by advertising your RIP network to the Internet, now is there?No worries—there are a few different ways to stop unwanted RIP updates from propagating across your LANs and WANs. The easiest one is through the passive-interface command. This command prevents RIP update broadcasts from being sent out a defined interface, but that same interface can still receive RIP updates.
© Copyright 2008 Course Outsource. All Rights Reserved. 286
© Copyright 2008 Course Outsource. All Rights Reserved.
Verifying RIPVerifying RIP
Router#show ip protocols
Router#show protocols
Router#show ip route
Router#debug ip rip
Router#undebug all (un all)
Show ip protocols: show routing protocols information and timersShow protocols: show routed protocol informationShow ip route: displays the routing tableDebug ip rip: show rip updates being sent and received on your routerUndebug all or no debug ip rip: turns off debugging
© Copyright 2008 Course Outsource. All Rights Reserved. 287
© Copyright 2008 Course Outsource. All Rights Reserved.
Verifying the RIP ConfigurationVerifying the RIP Configuration
A B CE0
S3S3S2S2E0172.16.1.0
10.2.2.3
192.168.1.0
10.2.2.210.1.1.210.1.1.1
172.16.1.1 192.168.1.1
This figure shows how the show ip protocol command is used to monitor RIP operation.The command displays the routing protocols that are active on the router for IP. It also gives network and timer information.Notice the list of networks for which the router is injecting routes and lastly, notice the administrative distance metric.
© Copyright 2008 Course Outsource. All Rights Reserved. 288
© Copyright 2008 Course Outsource. All Rights Reserved.
Displaying the IP Routing TableDisplaying the IP Routing Table
A B CE0
S3S3S2S2E0172.16.1.0
10.2.2.3
192.168.1.0
10.2.2.210.1.1.210.1.1.1
172.16.1.1 192.168.1.1
This figure displays the show ip route command, which displays the contents of the router’s IP routing table.Notice the locations of the hop count (metric) and the administrative distance (120).
R—Refers to routes learned from RIP.via—Refers to the router that informed us about this route.00:00:07 timer value—RIP updates are every 30 seconds. Ask, “How long until the next update?”The interfaces used for the best path