1. Network Management
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2. Objectives
• Understand different features of Access List.
• Explain standard and extended IP Access Lists.
• Understand IOS software and how to load IOS
software.
• Understand how to backup and restore Cisco IOS.
• Understand how to backup and restore Cisco
configuration.
• Understand Cisco Discovery Protocol.
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3. Access List
An access list is essentially a list of conditions that control
access both to and form a network segment. Access lists
can filter unwanted packets and be used to implement
security policies.
The IP and IPX access lists work similarly – they're both
packet filters.
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4. Access List contd..
There are a few important rules a packet follows when it's
being compared with an access list:
• It's always compared with each line of the access list in
sequential order.
• It's compared with lines of the access list only until a
match is made. Once the packet matches a line of the
access list, it's acted upon, and no further comparisons
take place.
• There is an implicit “deny" at the end of each access list-
this means that if a packet doesn't match up to any lines
in the access list, it'll be discarded.
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5. Access List contd..
There are two types of access lists used with IP and IPX:
• Standard access lists: These use only the source IP
address in an IP packet to filter the network.
• Extended access lists: These check for both source
and destination IP address, protocol field in the
Network layer header, and port number at the
Transport layer header.
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6. Access List contd..
Once you create an access list, you apply it to an interface
with either an inbound or outbound list:
• Inbound access lists: Packets are processed through
the access list before being routed to the outbound
interface.
• Outbound access lists: Packets are routed to the
outbound interface and then processed through the
access list.
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7. Access List contd..
Standard IP Access Lists
Standard IP access lists filter the network by using the
source IP address in an IP packet. You create a standard IP
access list by using the access-list numbers 1-99.
You can specify access lists by names for the protocols
listed below:
• Apollo Domain
• IP
• IPX
• ISO CLNS
• NetBIOS IPX
• Source-route bridging NetBIOS
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8. Standard IP Access Lists contd..
RouterA(config)#access-list ?
<1-99> IP standard access list
<100-199> IP extended access list
<1000-1099> IPX SAP access list
<1100-1199> Extended 48-bit MAC address access list
<1200-1299> IPX summary address access list
<200-299> Protocol type-code access list
<300-399> DECnet access list
<400-499> XNS standard access list
<500-599> XNS extended access list
<600-699> Appletalk access list
<700-799> 48-bit MAC address access list
<800-899> IPX standard access list
<900-999> IPX extended access list
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9. Standard IP Access Lists contd..
Wildcards
• Wildcards are used with access lists to specify a host,
network, or part of a network.
• Block size: Some of the different block sizes available
are 64, 32, 16, 8, and 4.
• When you need to specify a range of addresses, you
choose the next-largest block size for your needs.
• Wildcards are used with the host or network address to
tell the router a range of available addresses to filter. To
specify a host, the address would look like this:
172.16.30.5 0.0.0.0
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10. Access List contd..
Extended IP Access Lists
Extended IP access lists give more detailed control
compared to standard lists which only allow you to deny or
permit traffic from a certain source.
Extended lists allow you to permit or deny particular TCP/IP
traffic based on the Transport protocol being used (TCP or
UDP) and the service or application (e.g. SMTP, Telnet)
from source addresses and destination addresses.
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11. IOS Software
Cisco IOS Software provides a wide range of functionality -
from basic connectivity, security, and network management
to technically advanced services that enable businesses to
deploy applications such as real-time trading, interactive
support, on-demand media, and unified messaging.
The functionality of Cisco IOS Software is the result of an
evolution. First-generation networking devices could only
store and forward data packets. Today, Cisco IOS software
can recognize, classify, and prioritize network traffic,
optimize routing, support voice and video applications, and
much more.
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12. IOS Software contd..
Cisco network platforms and the Cisco IOS Software
running on them are a unified system - one that is a firm
foundation for building Internet applications.
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13. IOS Software contd..
Each time you switch on the router, it goes through power-
on self-test (POST) diagnostics to verify basic operation of
the CPU, memory and network interfaces.
The system bootstrap software in ROM (boot image)
executes and searches for valid router operating system
software (Cisco IOS image).
There are three places to find the Cisco IOS image to load:
• Flash memory
• TFTP server
• ROM
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14. IOS Software contd..
Default (Normal) Boot Sequence
After power on router does POST. Bootstrap starts IOS load.
Check the startup-config file in NVRAM for boot-system
commands (normally there aren't any). Then load IOS from
Flash.
Boot System Commands
Router(config)# boot system flash IOS_filename
Router(config)#boot system tftp IOS_filename
tftp_server_ip_address
Router(config)# boot system rom
Router#copy running-config startup-config
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15. IOS Software contd..
Configuration Register Command
Router(config)# config-register 0x10x
where that last x is 0 - F in hex
When the last x is:
0 = boot into ROM Monitor mode
1 = boot the ROM IOS
2 - 15 = look in startup config file in NVRAM
To check the boot field setting, and to verify the config-
register command, use the show version command.
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16. Backing Up and Restoring Cisco IOS
Before you upgrade or restore a Cisco IOS, you should copy
the existing file to a TFTP host as a backup in case the new
image does not work.
Verify Flash Memory
By using the show flash command you can verify the
amount of flash memory and the file or files being stored in
flash memory.
Router#sh flash
System flash directory:
File Length Name/status
1 8121000 c2500-js-l.112-18.bin
[8121064 bytes used, 8656152 available, 16777216 total]
16384K bytes of processor board System flash (Read ONLY)
Router#
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17. Backing Up and Restoring Cisco IOS contd..
Back Up Cisco IOS
To back up the Cisco IOS to a TFTP host, you use the copy
flash tftp command. This command requires only the
source filename and the IP address of the TFTP host.
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18. Back Up Cisco IOS contd..
Router#copy flash tftp
System flash directory:
File Length Name/status
1 8121000 c2500-js-l.112-18.bin
[8121064 bytes used, 8656152 available, 16777216 total]
Address or name of remote host [255.255.255.255]?
192.168.0.120
Source file name?c2500-js-l.112-18.bin
Destination file name [c2500-js-l.l12-18.bin]?[Enter]
Verifying checksum for 'c2500-js-l.l12-18.bin')file #1)
...OK
Copy '/c2500-js-l.112-18' from Flash to server
as '/c2500-js-l.112-18'? [yes/no]y
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!! [output cut]
Upload to server done
Flash copy took 00:02:30 [hh:mm:ss]
Router#
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19. Backing Up and Restoring Cisco IOS contd..
Restoring or Upgrading the Cisco Router IOS
You may need to restore the Cisco IOS to flash memory to
replace an original file that has been damaged or to
upgrade the IOS.
You can download the file from a TFTP host to flash
memory by using the copy tftp flash command.
Router#copy tftp flash
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20. Backing Up and Restoring the Cisco
Configuration
Any changes that you make to the router configuration are
stored in the running-config file.
If you do not perform a copy run start command after you
make a change to running-config, that change will be gone if
the router reboots or gets powered down.
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21. Backing Up and Restoring the Cisco Configuration
contd..
Backing Up the Cisco Router Configuration
To copy the router's configuration from a router to a TFTP
host, you can use either the copy running-config tftp or
copy startup-config tftp command.
Verifying the Current Configuration
To verify the configuration in DRAM, use the show running-
config command as follows:
Router#sh run
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22. Backing Up the Cisco Router Configuration
contd..
Verifying the Stored Configuration
Next, you should check the configuration stored in NVRAM.
To see this, use the show startup-config command as
follows:
Router#sh start
Copying the Current Configuration to NVRAM
Router#copy run start
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23. Backing Up the Cisco Router Configuration
contd..
Copying the Configuration to a TFTP Host
Once the file is copied to NVRAM, you can make a second
backup to a TFTP host by using the copy running-config
tftp command, as follows:
Router#copy run tftp
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24. Backing Up and Restoring the Cisco Configuration
contd..
Restoring the Cisco Router Configuration
If you copied the router's configuration to a TFTP host as a
second backup, you can restore the configuration using the
copy tftp running-config command or the copy tftp
startup-config command, as shown below.
Router#copy tftp run
Erasing the Configuration
To delete the startup-config file on a Cisto router, use the
command erase startup-config, as follows:
Router#erase startup-config
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25. Cisco Discovery Protocol (CDP)
CDP is a proprietary protocol designed by Cisco to help
administrators collect information about both locally attached
and remote devices.
The show cdp command shows information about two CDP
global parameters that can be configured on Cisco devices:
• CDP timer is how often CDP packets are transmitted
to all active interfaces.
• CDP holdtime is the amount of time that the device
will hold packets received from neighbor devices.
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