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1
Data Forwarding
Basic Router Configuration
Overview
In this session, we sill be looking at Review : router backplane
Ethernet, console and serial interfaces Configuring router interfaces
Ethernet and serial interface Viewing router configurations
Using show commands Testing network connectivity
Using ping command
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Addressing - Review
4
What is Routing?
Routing - Selecting the correct path towards destination Build Routing table for
path selection Two methods
Static Dynamic
Router
1
23
0111
value in arrivingpacket’s header
routing algorithm
local forwarding table
header value output link
0100010101111001
3221
5
Routers –Interfaces
Routers have LAN interfaces
Ethernet interfaces: Have MAC Addresses IP addresses
WAN interfaces Serial interfaces Have IP addresses
Serial 0192.168.10.1 255.255.255.252
Ethernet 1 172.16.2.1/ 255.255.255.0 MAC: 0abbccddeeff
Ethernet 0172.16.1.1/ 255.255.255.0
MAC: 0cddeeffaabb
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Review: Cisco Router backplane Identify the different interfaces on router
Interface 1 Interface 2 Interface 3 Interface 4
Serial interface
console interfaceEthernet interface
Interface 1 Interface 2
Interface 3
Interface 4
Router Components
RAM – holds packet buffers, routing table, running-config is stored in RAM,
ROM – starts and maintains the router Flash memory – holds the IOS;
is not erased when the router is reloaded; is an EEPROM [Electrically Erasable Programmable Read-Only Memory]
NVRAM – Non-Volatile RAM - holds router configuration; is not erased when router is reloaded
Where Is The Configuration?
Can also be stored in more permanent places: External hosts, using TFTP (Trivial File Transfer Protocol) In flash memory in the router
Copy command is used to move it around
copy run start copy run tftp copy start tftp copy tftp start copy flash start copy start flash
Identify network boundaries
128.143.100.32/24 255.255.255.0
128.143.102.32/24 255.255.255.0
128.143.101.32/24 255.255.255.0
128.143.10.33/24 255.255.255.0
R R
•Can you identify different networks and network addresses ?•Identify network class •What is the maximum number of hosts that can be hosts can be connected on each of these networks?
10
Review: Establishing a Hyper-terminal Session
• All Cisco routers include an EIA/TIA-232 asynchronous serial console port (RJ-45).
• How do you connect to router to configure?
• Router configured from PC connected to router console port using a rollover cable
• Rollover cable has•Serial interface adapter on one side and •RJ45 adapter on the other
PC
Serial adapter
RJ45 adapter
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Routing Types
Example: Static Routing
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Connections to the Router- cables
Connections of a Router for Ethernet 2 types of cables can be used:
Straight through and Cross-over Straight through used to connect
dissimilar devices Switch-to-Router, Switch-to-PC,
Cross-over used to connect
similar devices: Switch-to-Switch, Router to PC (Host) PC-to-PC, Switch-to-Hub, Hub-to-Hub, Router-to-Router
Cross-over Straight-thru
Straight-thru
Logging Into The Router Connect router to console port or telnet to router
– router>– router>enable– password– router#– router#?
Configuring the router– Terminal (entering the commands directly)– router# configure terminal– router(config)#
USER MODE PROMPT
PRIVILEDGED MODE PROMPT
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Configuring router Interfaces
-By default all interfaces are down Ethernet Serial
Interface configured with IP address and subnet mask
No Shutdown command used to enable the interface
Ethernet interface
New Router Configuration Process
Load configuration parameters into RAM Router#configure terminal
Personalize router identification Router#(config)hostname RouterA
Assign access passwords RouterA#(config)line console 0 RouterA#(config-line)password cisco RouterA#(config-line)login
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To configure an Ethernet interface -Enter interface configuration mode (config) -Enter IP address and subnet mask -Enter no shutdown command Example:
-R2(config)#interface fastethernet 0/0 -R2(config-if)#ip address 172.16.1.1 255.255.255.0 -R2(config-if)#no shutdown
Configuring Interfaces –Ethernet Interface
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Configuring Interfaces – Serial Interface
Configuring a Serial interface -Enter interface configuration mode -Enter in the ip address and subnet mask -Enter in the no shutdown command
Example: -R1(config)#interface serial 0/0 -R1(config-if)#ip address 172.16.2.1 255.255.255.0 -R1(config-if)#no shutdown
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Configuring serial links in a lab environment Serial Interfaces require a clock signal to control the timing of
the communications One end of serial interface is DCE end and other end is DTE
end configure timing on the DCE end of serial interface.
R1# show interface serial 0/0
If it is DCE interface then configure clock rate -R1(config)#interface serial 0/0 -R1(config-if)#clock rate 64000
Serial Interface – setting clock rate
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Verify configuration Use show commands
-Show interfaces fastEthernet 0/0 -Show ip interface brief -Show running-config
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Testing the network connectivity
To check the connectivity Run ‘ping’ command
Between Host 1 and Host 3 Host 1 and router Host 2 and router Host 3 and router
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Review: Default Gateway
When a LAN is connected to a Router, Default Gateway is the address of router interface connected to that LAN.
The IP address and subnet mask is on the same network as the hosts on that network
Router
LAN
Router
Default Gateway
Global Configuration
Static route creation:
IP route <n.n.n.n> <m.m.m.m> <g.g.g.g> n.n.n.n = network block m.m.m.m = network mask denoting block size g.g.g.g = next hop gateway destination packets
are sent to
23
Static Routes
The NO Command
Used to reverse or disable commands e.g
ip domain-lookup no ip domain-lookup router ospf 1 no router ospf 1 ip address 1.1.1.1 255.255.255.0 no ip address
Looking At The Configuration
Use “show running-configuration” to see the current configuration
Use “show startup-configuration” to see the configuration in NVRAM, that will be loaded the next time the router is rebooted or reloaded
Getting Online Help IOS has a built-in help facility; use “?” to get a list of
possible configuration statements
“?” after the prompt lists all possible commands: router#?
“<partial command> ?” lists all possible subcommands, e.g.: router#show ? router#show ip ?
Getting Online Help
This also works in configuration mode: router(config)#ip a? accounting-list accounting-threshold
accounting-transits address-pool alias as-path
router(config)#int e0/0 router(config-if)#ip a? access-group accounting address
Getting Lazy Help TAB character will complete a partial word
hostel-rtr(config)#int<TAB> hostel-rtr(config)#interface et<TAB> hostel-rtr(config)#interface ethernet 0 hostel-rtr(config-if)#ip add<TAB> hostel-rtr(config-if)#ip address ...
n.n.n.n m.m.m.m Not really necessary; partial commands can be used:
router#conf t router(config)#int e0/0 router(config-if)#ip addr n.n.n.n
Deleting Your Router’s Configuration
To delete your router’s configuration Router#erase startup-config Router#reload
Router will startup again, but in setup mode, since startup-config file does not exists
How many Static Routes?
30
Conclusion
Today we learnt to Configure router interfaces
Ethernet and Serial Set clock rate on serial interface Set up and tested the testbed network
Design IP addressing Configure ethernet interfaces Verified configurations used ping to test network
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