ccna2 - 1 -configuring network devices and introduction to routing
Post on 04-Jun-2018
230 Views
Preview:
TRANSCRIPT
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
1/60
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
WELCOME TOCCNA 2
Some important info to follow
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
2/60
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Before we begin....Practical Sessions
You need to attend your practical session every week to avoid fallingbehind
Online Chapter Tests Will be active for 1 week following the theory lecture
Passing requirements You need to pass
both the CCNA 2 and CCNA 3 online final exam and the skillsexam with 70%
the written exam in November with 50%
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
3/60
Configuring Network Devices &Introduction to Routing
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
4/60
The purpose of Cisco IOSSoftware
As with a computer, a router or switch cannot functionwithout an operating system.Cisco calls its operating system the Cisco InternetworkOperating System or Cisco IOS.
The Cisco IOS provides the following network services:Basic routing and switching functionsReliable and secure access to networked resourcesNetwork scalability
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
5/60
Router user interfaceThe Cisco IOS software uses a command-lineinterface (CLI) as the traditional consoleenvironment.This environment is accessible through several
methods:Console AUX port (modem)Telnet
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
6/60
Router user interface modes
The IOS provides a command interpreter service known asthe command executive ( EXEC ).
After each command is entered, the EXEC validates andexecutes the command.The levels are user EXEC mode and privileged EXECmode .
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
7/60
Cisco IOS software features
Although there are numerous IOS images fordifferent Cisco device models and feature sets, thebasic configuration command structure is thesame.
The naming convention for the different Cisco IOSreleases contains three parts:The platform on which the image runsThe special features supported in the imageWhere the image runs and whether it has been
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
8/60
Operation of Cisco IOS Software
The Cisco IOS devices have three distinct operatingenvironments or modes:
ROM monitorBoot ROM
Cisco IOS
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
9/60
Troubleshooting command line errorsHelp is at hand.. When in doubt use the ? to see what commandoption are available
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
10/60
Examining the initial routerbootup
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
11/60
Examining the initial routerbootup
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
12/60
Examining the initial routerbootup
no
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
13/60
Device management
Out-of-band management requires a computer to be directlyconnected to the console port or auxiliary port (AUX) of thenetwork device being configured.Use in-band management to monitor and make configurationchanges to a network device over a network connection.
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
14/60
Establishing a HyperTerminalsession
Take the following steps to connect a terminal to the consoleport on the router:Connect the terminal using the RJ-45 to RJ-45 rollovercable and an RJ-45 to DB-9 or RJ-45 to DB-25 adapter.Configure the terminal or PC terminal emulation softwarefor 9600 baud, 8 data bits, no parity, 1 stop bit, and no flow
Rollovercable
Consoleport
Com1 or Com2 serialport
Terminal ora PC with
terminalemulationsoftware
Router
bl h l
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
15/60
Establishing a HyperTerminalsession
Important: A console connection is not the same as anetwork connection!
=
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
16/60
Logging into the router
16
Two commands can be used to set a password used toaccess privileged EXEC mode: enable password andenable secret The following are specific modes that can also be accessedfrom the global configuration mode:
InterfaceSubinterfaceLine
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
17/60
Keyboard help in the router CLI
17
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
18/60
Keyboard help in the router CLI
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
19/60
Enhanced editing commands
Ctrl-Z is a command used to back out of configurationmode. This will return the user to the privileged EXECmode prompt.
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
20/60
Router command history
terminal history size : maximum number ofcommands is 256
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
21/60
Router as a Computer
The basic purpose of a router-Computers that specialize in sending packets overthe data network. They are responsible forinterconnecting networks by selecting the best path
for a packet to travel and forwarding packets to theirdestinationRouters are the network center
-Routers generally have 2 types of connections:
-WAN connection (Connection to ISP)-LAN connection
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
22/60
Router as a ComputerData is sent in form of packets between 2 enddevicesRouters are used to direct packet to its destination
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
23/60
Router as a ComputerRouters examine a packets destination IP address
and determine the best path by enlisting the aid ofa routing table
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
24/60
Router components and their functions
CPU - Executes operating system instructions
Random access memory (RAM) - Contains the running copy ofconfiguration file. Stores routing table. RAM contents lost when power isoff
Read-only memory (ROM) - Holds diagnostic software used when routeris powered up. Stores the routers bootstrap program.
Non-volatile RAM (NVRAM) - Stores startup configuration. This mayinclude IP addresses (Routing protocol, Hostname of router)
Flash memory - Contains the operating system (Cisco IOS)
Interfaces - There exist multiple physical interfaces that are used toconnect network. Examples of interface types:-Ethernet / fast Ethernet interfaces-Serial interfaces-Management interfaces
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
25/60
Router components
h h b
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
26/60
Major phases to the router boot-up
Test router hardwarePower-On Self Test
(POST)Execute bootstrap loader
Locate & load Cisco IOSsoftware-Locate IOS-Load IOS
Locate & load startupconfiguration file or entersetup mode-Bootstrap program looks
for configuration file
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
27/60
Verify the router boot-up process
The show version command is used to viewinformation about the router during thebootup process. Information includes:
Platform model numberImage name & IOS versionBootstrap version stored in ROMImage file name & where it was loaded fromNumber & type of interfaces
Amount of NVRAM Amount of flashConfiguration register
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
28/60
Info we can see at boot time
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
29/60
Router Interfaces
Router Interface is a physical connector that enablesa router to send or receive packetsEach interface connects to a separate networkConsist of socket or jack found on the outside of arouterTypes of router interfaces:
-Ethernet-Fastethernet-Serial-DSL-ISDN
-Cable
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
30/60
Router InterfacesTwo major groups of Router Interfaces
LAN Interfaces:
Are used to connect router to LANnetworkHas a layer 2 MAC address
Can be assigned a Layer 3 IPaddressUsually consist of an RJ-45 jack
WAN Interfaces
Are used to connect routers to external networks thatinterconnect LANs.
Depending on the WAN technology, a layer 2 addressmay be used.
Uses a layer 3 IP address
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
31/60
Routers and the Network Layer
Routers use destination IP address to forwardpackets
The path a packet takes is determined after a routerconsults information in the routing table.
After router determines the best path
Packet is encapsulated into a frameFrame is then placed on network medium in form of Bits
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
32/60
Routers Operate at Layers 1, 2 & 3Router receives a stream of encoded bits
Bits are decoded and passed to layer 2Router de-encapsulates the frameRemaining packet passed up to layer 3
Routing decision made at this layer by examining destination IP
addressPacket is then re-encapsulated & sent out outboundinterface
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
33/60
Implementing Basic AddressingSchemes
When designing a new network or mapping anexisting network you must provide the followinginformation in the form of a document:
-Topology drawing that Illustrates physical connectivity
Address table that provides the following information:Device nameInterfaces usedIP addresses
Default gateway
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
34/60
Basic Router Configuration A basic router configuration should contain thefollowing:
-Router name - Host name should be unique-Banner - At a minimum, banner should warnagainst unauthorized use
-Passwords - Use strong passwords-Interface configurations - Specify interfacetype, IP address and subnet mask. Describepurpose of interface. Issue no shutdown
command. If DCE serial interface issue clockrate command. After entering in the basic configuration the followingtasks should be completed
-Verify basic configuration and routeroperations.
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
35/60
Configure Devices and Apply AddressesVerify Basic Router Configuration
-Issue the show running-config command-Save the basic router configuration by Issuing thecopy running-config startup-config command
-Additional commands that will enable you to furtherverify router configuration are:
Show running-config - Displays configuration currently inRAMShow startup-config - Displays configuration file NVRAMShow IP route - Displays routing tableShow interfaces - Displays all interface configurationsShow IP int brief - Displays abbreviated interfaceconfiguration information
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
36/60
Routing Table StructureRouting Table is stored in ram and containsinformation about:
Directly connected networks - this occurs when adevice is connected to another router interface
Remotely connected networks - this is a networkthat is not directly connected to a particular routerDetailed information about the networks include
source of information, network address & subnet
mask, and Ip address of next-hop routerShow ip route command is used to view a routingtable
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
37/60
Routing Table StructureRouter interfaces
Each router interface is a member of a different network Activated using the no shutdown commandIn order for static and dynamic routes to exist inrouting table you must have directly connectednetworks
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
38/60
Static RoutesStatic routes in the routing table
-Includes: network address and subnet mask and IPaddress of next hop router or exit interface-Denoted with the code S in the routing table
-Routing tables must contain directly connectednetworks used to connect remote networks beforestatic or dynamic routing can be used
When to use static routes
-When network only consists of a few routers-Network is connected to internet only through oneISP-Hub & spoke topology is used on a large network
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
39/60
Connected and Static routes
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
40/60
Dynamic routing protocolsDynamic routing protocols
-Used to add remote networks to a routing table-Are used to discover networks-Are used to update and maintain routing tables
Automatic network discovery-Routers are able discover new networks by sharingrouting table information
Maintaining routing tables-Dynamic routing protocols are used to share routing information withother router & to maintain and up date their own routing table.
IP routing protocols. Example of routing protocols include:-RIP-IGRP-EIGRP-OSPF
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
41/60
Connected. Static and Dynamic
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
42/60
Routing Table Principles3 principles regarding routing tables:
Every router makes its decisions alone , based onthe information it has in its routing table.Different routing table may contain different
information A routing table can tell how to get to a destinationbut not how to get back
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
43/60
Effects of the 3 Routing Table Principles
-Packets are forwarded through the network from one routerto another, on a hop by hop basis.
-Packets can take path X to a destination but return via pathY (Asymmetric routing).
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
44/60
Internet Protocol (IP) packetInternet Protocol (IP) packet format contains fieldsthat provide information about the packet and thesending and receiving hostsFields that are importance for CCNA students:
-Destination IP address-Source IP address-Version & TTL-IP header length-Precedence & type of service-Packet length
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
45/60
Internet Protocol (IP)
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
46/60
MAC Layer Frame Format
MAC Frames are also divided into fields. Theyinclude:
-Preamble-Start of frame delimiter-Destination MAC address-Source MAC address-Type/length
-Data and pad-Frame check sequence
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
47/60
MAC Layer Frame Format
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
48/60
Router Metrics A Metric is a numerical value used by routing protocols helpdetermine the best path to a destination
The smaller the metric value the better the path2 types of metrics used by routing protocols are:
-Hop count - this is the number of routers a packet must travelthrough to get to its destination-Bandwidth - this is the speed of a link also known as the datacapacity of a link
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
49/60
Router Paths with Equal MetricsEqual cost metric is a condition where a router has multiplepaths to the same destination that all have the same metricTo solve this dilemma , a router will use Equal Cost LoadBalancing . This means the router sends packets over the multipleexit interfaces listed in the routing table.
Ro ter Paths and Packet
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
50/60
Router Paths and PacketSwitchingPath determination is a process used by a router to pick the bestpath to a destinationOne of 3 path determinations results from searching for the bestpath
Directly connected networkRemote networkNo route determined
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
51/60
Router Packet SwitchingSwitching Function of Router is the processused by a router to switch a packet from anincoming interface to an outgoing interface onthe same router.
-A packet received by a router will do thefollowing:
Strips off layer 2 headers.Examines destination IP address located in
Layer 3 header to find best route todestination.Re-encapsulates layer 3 packet into layer 2
frame.Forwards frame out exit interface.
A k l f ki
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
52/60
As a packet travels from one networkingdevice to another
-The Source and Destination IP addresses NEVER change-The Source & Destination MAC addresses
CHANGE as packet is forwarded from onerouter to the next.-TTL field decrement by one until a value ofzero is reached at which point router discardspacket (prevents packets from endlesslytraversing the network)
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
53/60
A Day in the life of a Packet
PC1 Wants to send something to PC 2 here is part ofwhat happensStep 1 - PC1 encapsulates packet into a frame. Framecontains R1s destination MAC address
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
54/60
A Day in the life of a Packet Step 2 - R1 receives Ethernet frame.
R1 sees that destination MAC address matches its own MAC.R1 then strips off Ethernet frame.R1 Examines destination IP.R1 consults routing table looking for destination IP.
After finding destination IP in routing table, R1 now looks upnext hop IP address.R1 re-encapsulates IP packet with a new Ethernet frame.R1 forwards Ethernet packet out Fa0/1 interface.
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
55/60
A Day in the life of a Packet
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
56/60
A Day in the life of a Packet Path determination and switching function details. PC1 Wants tosend something to PC 2 here is part of what happens
Step 3 - Packet arrives at R2R2 receives Ethernet frameR2 sees that destination MAC address matches its own MACR2 then strips off Ethernet frameR2 Examines destination IPR2 consults routing table looking for destination IP
After finding destination IP in routing table, R2 now looks upnext hop IP addressR2 re-encapsulates IP packet with a new data link frameR2 forwards Ethernet packet out S0/0 interface
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
57/60
A Day in the life of a Packet Step 4 - Packet arrives at R3
R3 receives PPP frameR3 then strips off PPP frameR3 Examines destination IPR3 consults routing table looking for destination IP
After finding destination IP in routing table, R3 is directly connectedto destination via its fast Ethernet interfaceR3 re-encapsulates IP packet with a new Ethernet frameR3 forwards Ethernet packet out Fa0/0 interface
Step 5 - IP packet arrives at PC2. Frame is decapsulated& processed by upper layer protocols.
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
58/60
SummaryRouters are computers that specialize in sending data over a network.Routers are composed of:
-Hardware i.e. CPU, Memory, System bus, Interfaces-Software used to direct the routing process
IOSConfiguration file
Routers need to be configured. Basic configuration consists of:-Router name-Router banner-Password(s)-Interface configurations i.e. IP address and subnet mask
Routing tables contain the following information-Directly connected networks-Remotely connected networks-Network addresses and subnet masks-IP address of next hop address
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
59/60
SummaryRouters determine a packets path to its destinationby doing the following
Receiving an encapsulated frame & examiningdestination MAC address.
If the MAC address matches then Frame is de-encapsulated so that router can examine thedestination IP address.If destination IP address is in routing table or there
is a static route then Router determines next hop IPaddress. Router will re-encapsulate packet withappropriate layer 2 frame and send it out to nextdestination.Process continues until packet reaches destination.Note - only the MAC addresses will change the
-
8/13/2019 CCNA2 - 1 -Configuring Network Devices and Introduction to Routing
60/60
top related