1. Instructor: Mr Malik Zaib
Chapter 5:
Managing a Cisco Internetwork
Instructor: Mr Malik Zaib

2. Chapter 5 Objectives Cisco Router Components Boot Sequence
Configuration register
Backing up and restoring the IOS
Backing up and restoring the configuration
Cisco Discovery Protocol
Telnet
Resolving hostnames
Troubleshooting tools 2

3. Cisco Router Components
Bootstrap
Brings up the router during initialization
POST(Power-on self-test)
Checks basic functionality; hardware & interfaces
ROM monitor
Manufacturing testing & troubleshooting, as well as running a mini-IOS when the IOS in flash fails to load.
Mini-IOS
Loads Cisco IOS into flash memory, Called the RXBOOT or bootloader by Cisco, the mini-IOS is small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory. The mini-IOS can also perform a few other maintenance operations.
RAM
Holds packet buffers, routing tables, & s/w
Stores running-config

4. Cisco Router Components
ROM
Starts & maintains the router, Holds the POST and the bootstrap program as well as the mini-IOS.
Flash Memory
Holds Cisco IOS
Not erased when the router is reloaded
A It is EEPROM (electronically erasable programmable read-only memory) created by Intel.
NVRAM
Holds router (& switch) configurations
Does not store an IOS.
Configuration Register
Controls how the router boots up
By default the value is set to 0x2102, which tells the router to load the IOS from flash memory as well as to load the configuration from NVRAM.

5. Boot Sequence 1: Router performs a POST
2: Bootstrap looks for & loads the Cisco
IOS
3: IOS software looks for a valid
configuration file
4: Startup-config file (from NVRAM) is
loaded
If startup-config file is not found, the router will start the setup mode

6. Backing up the Configuration
1: Verify the Current Configuration
Router#sh run
2: Verify the Stored Configuration
Router#sh start
Verify available memory
3: Copy running-config to NVRAM
Router#copy run start
4: Copy running-config to a TFTP host
Router#copy run tftp
A second backup

7. Restoring the Configuration
Used when…
You need to copy the startup-config to the running-config
Errors made in editing the running-config
Changes made at the TFTP host need to be copied to the running-config or startup-config
Router#copy tftp run or Router#copy tftp start
NOTE: The configuration file is ASCII. Any text editor will enable changes
Erasing the Configuration
Router#erase startup-config
Note: When the router reboots it will be in setup mode

8. Configuring DHCP
To configure a DHCP server for your hosts, you need the following information at minimum:
Network and mask for each LAN Network ID, also called a scope. All addresses in a subnet can be leased to hosts by default.
Reserved/excluded addresses Reserved addresses for printers, servers, routers, etc.
These addresses will not be handed out to hosts. I usually reserve the first address of each subnet for the router, but you don’t have to do this.
Default router This is the router’s address for each LAN.
DNS address A list of DNS server addresses provided to hosts so they can resolve names.

9. DHCP Configuration Steps
Here are your configuration steps:
1. Exclude the addresses you want to reserve. The reason you do this step first is because as soon as you set a network ID, the DHCP service will start responding to client requests.
2. Create your pool for each LAN using a unique name.
3. Choose the network ID and subnet mask for the DHCP pool that the server will use to provide addresses to hosts.
4. Add the address used for the default gateway of the subnet.
5. Provide the DNS server address(es).
6. If you don’t want to use the default lease time of 24 hours, you need to set the lease time in days, hours, and minutes.

10. DHCP Configuration Commands
Switch(config)#ip dhcp excluded-address
Switch(config)#ip dhcp pool Sales_Wireless
Switch(dhcp-config)#network
Switch(dhcp-config)#default-router
Switch(dhcp-config)#dns-server
Switch(dhcp-config)#lease
DHCP Configuration example on a switch

11. DHCP Relay
we can configure the F0/0 interface of the router to accept the DHCP client
requests and forward them to the DHCP server like this:
Router#config t
Router(config)#interface fa0/0
Router(config-if)#ip helper-address

12. Verifying DHCP on Cisco IOS
There are some really useful verification commands to use on a Cisco IOS device for monitoring and verifying a DHCP service.
show ip dhcp binding Lists state information about each IP address currently leased to a client.
show ip dhcp pool [poolname] Lists the configured range of IP addresses, plus statistics for the number of currently leased addresses and the high watermark for leases from each pool.
show ip dhcp server statistics Lists DHCP server statistics—a lot of them!
show ip dhcp conflict If someone statically configures an IP address on a LAN and the
DHCP server hands out that same address, you’ll end up with a duplicate address. This isn’t good, which is why this command is so helpful!

13. Using Cisco Discovery Protocol (CDP)
A Cisco proprietary protocol
Designed to collect information about directly attached & remote devices
Hardware information
Protocol information
Useful in troubleshooting & documenting the network

14. Getting CDP Timers & Holdtime Information
Configuration
CDP Timer: How often CDP packets are transmitted to all active interfaces
CDP Holdtime: The amount of time that the device will hold packets received from neighbor devices
Router#sh cdp
Global CDP information
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Router#config t
Router(config)#cdp timer 90
Router(config)#cdp holdtime 240

15. Getting Neighbor Information
Shows information about directly connected devices
CDP packets are not passed through a Cisco switch
Can only see what is directly attached
Router#sh cdp nei or
Router#sh cdp neighbor detail
Detailed information; hostname, IP address, etc

16. Getting Interface Traffic & Port Information
Interface Traffic Information:
CDP packets sent & received
Errors with CDP
Router#sh cdp traffic
Port & Interface Information:
Encapsulation on the line
Timer & Holdtime for each interface
Router#sh cdp interface

17. Documenting the network with CDP

18. Documented !!

19. Using Telnet A virtual terminal protocol Part of the TCP/IP suite
Allows connections to remote devices
Gather information
Run programs
Note: The VTY passwords must be set on the routers

20. Using Telnet Setting VTY passwords: Router#config t
Router(config)#line vty 0 4
Router(config)#login
Router(config)#password cisco
Router(config)#^Z
Router#
Trying … Open
User Access Verification
Password:
RouterB>

21. Using Telnet Setting VTY password: Remember…. Router#config t
Router(config)#line vty 0 4
Router(config)#login
Router(config)#password cisco
Router(config)#^Z
Router#
Trying … Open
User Access Verification
Password:
RouterB>
Remember….
VTY password is the user mode (>) password - not the enable mode (#) password
With no enable/enable secret password set, the following happens:
RouterB>en
% No password set
RouterB>
This equates to good security!

22. Telnet Commands Telnetting into Multiple Devices
Ctrl+Shift+6 (release) X
Checking Telnet Connections
Router#sh sessions
Checking Telnet Users
Router#sh users
Closing Telnet Sessions
RouterB>exit
RouterB>disconnect

23. Resolving Hostnames
To use a hostname rather than an IP address to connect to a remote host a device must be able to translate the hostname to an IP address
Build a host table on each router
Build a Domain Name System (DNS) server

24. Building a Host Table
Provides name resolution only on the router on which it is built
[ip host name tcp_port_number ip_address]
Router(config)#ip host RouterB
Router(config)#ip host switch
Router#sh hosts
Default TCP port number: 23
Router#RouterB
RouterB#(Ctrl+Shift+6) (X)
Router#switch

25. Using DNS to Resolve Names
Used when you have many devices on your network
Making DNS work…
ip domain-lookup
Turned on by default
ip name-server
Sets the IP address of the DNS server (up to 6 each)
ip domain-name
Appends the domain name to the hostname
Ex: RouterA.neversail.navy.mil

26. Checking Network Connectivity
Ping
Displays the minimum, average, & maximum times it takes for aping packet to find a specified system + return
Router#ping RouterB
Trace
Shows the path a packet takes to get to a remote device
Router#trace RouterB

27. Summary Go through all the written and review questions
Go through the answers with the class 27