GD Networking Newbie: CCNA v3.0

http://ccnaxv3.blogspot.com/

Cisco is leading company in manufacturing computer networking related equipment like routers and switches. It certifies the persons working with its products at five different levels.

1. Entry Level

2. Associate Level

3. Professional Level

4. Expert Level

5. Architect Level

Like almost every IT related certificate and device which update their product and name them with different version, Cisco has announced to update its contents for CCNA routing and switching and named it CCNAX.

The updated name: The update name is CCNAX Cisco Certified Network Associate (Accelerated). The updated number: The new course number is CCNAv3.0 200 - 125

As before, to get CCNA certification, one can follow one of the two ways.

Either you can give two exams separately

              i) 100-105 ICND1   Interconnecting Cisco Networking Devices Part 1
             ii) 200-105 ICND2 v3.0  Interconnecting Cisco Networking Devices Part 2

OR you can appear only for one combined exam

                200-125 CCNA Interconnecting Cisco Networking Devices: Accelerated (CCNAX)

Cisco deals with network and networking device.

COMPUTER NETWORK:

To be specific, computer network is defined to be a group of computer of networks joined/connected/ attached with each other.

For example, refer to the following figure.

Computer Networking

Computers are connected with each other with the help of some networking device like hub, switch, router etc.

Hub: is a network device which works on physical layer, therefore does not understand MAC address or the network address.

When hub receives packet from any node connected to it, it just copies that packet to all other nodes connected with it. It does not filters packet to only be received by specific target node.

Hub

Router

Switch: is a networking device which works on Packet Link Layer, therefore it understands the MAC address of the nodes.

When switch receives packet from any node connected to it, it only copies that packet to the specific targeted node. It filters packets based on the MAC addresses of the nodes.

Router: is a networking device which works on network layer, therefore it understands network address of the nodes.

With router receives packet from any node connected to it, it looks its IP address and forwards the packet to that specific network for which that packet is destined for.

Switch

CARRIER SENSE MULTIPLE ACCESS/ COLLISION DETECTION

CSMA/CD

A node in the network can start transmitting anytime. If there is only one node transmitting at a time than there is no issue.

However, when there are more than one computer nodes trying at the same time.

This can create collision among the transmitting nodes as seen above.

In case of collision, a signal is generated on the medium to inform other nodes on the network that there is collision on the medium. As a result, all the nodes on the network wait for some time until the medium is free. After this "some time" every host has equal right to transmit.

NETWORKING CABLES

Networking Cable : A networking cable is a physical medium/ path through data/ information is transmitted from one point to other.

In the figure above, two computes are connected with a printer through some cable.

Different types of nodes/computers are connected with different types of cables. These cable types are explained as follows.

Types of Networking Cables.

1. Straight-through cable

2. Crossover

3. Rolled over

Straight-through cable: A cable with following connection setup is called straight through cable.

Here out of Eight wires, first wire is connected with the first one, second with the second, third with the third and last, the sixth one with the sixth wire. The actual wire looks like.

Straight Through Cable

Rollover Cable: Cable with rollover connection as shown bellow is called a rollover cable. It is used to connect computers' EIA-TIA 232 interface to a router console serial communication (COM) port.

Rollover

Snapshot of a rollover cable is given bellow.

Snapshot of Rollover Cable

Uses of cross-over and straight-through cables:

Moreover, the use of crossover and straight-through cable is given in the following table.

	Crossover Cable	Straight-through Cable
1.	Switch to switch	Host to switch OR hub
2.	Hub to hub	Router to switch OR hub
3.	Router to router
4.	Host to host
5.	Hub to switch
6.	Router direct to host

CONNECTING WITH THE ROUTER

A router can be made functional with the help of operating system installed into it. This operating system is called Internetwork Operating System (IOS).

IOS of a router or in other words a router can be connected by following three different methods.

Through Console Port: A rollover cable is used to connect RS-232 port of a computer with the router's console serial communication (COM) port. Pictorial illustration is given bellow.

Through Auxiliary Port:

An RJ-45 connector is used to connect AUX port of a router with the modem as shown bellow.

With auxiliary port, we can get access to Cisco IOS remotely using modem.

Through Telnet or Secure Shell (SSH): In this method, Cisco IOS is accessed using a program called Telnet over the Internet.

After connecting with Cisco router, as soon as it is turned ON, the following setup mode is shown for some preliminary configuration.

System Bootstrap, Version 15.1(4)M4, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Total memory size = 512 MB - On-board = 512 MB, DIMM0 = 0 MB

CISCO2901/K9 platform with 524288 Kbytes of main memory

Main memory is configured to 72/-1(On-board/DIMM0) bit mode with ECC disabled

Readonly ROMMON initialized

program load complete, entry point: 0x80803000, size: 0x1b340

IOS Image Load Test

___________________

Digitally Signed Release Software

program load complete, entry point: 0x81000000, size: 0x3bcd3d8

Self decompressing the image :

########################################################################## [OK]

Smart Init is enabled

smart init is sizing iomem

TYPE MEMORY_REQ

Onboard devices &

buffer pools 0x0228F000

-----------------------------------------------

TOTAL: 0x0228F000

Rounded IOMEM up to: 36Mb.

Using 6 percent iomem. [36Mb/512Mb]

Restricted Rights Legend

Use, duplication, or disclosure by the Government is

subject to restrictions as set forth in subparagraph

Rights clause at FAR sec. 52.227-19 and subparagraph

Software clause at DFARS sec. 252.227-7013.

cisco Systems, Inc.

170 West Tasman Drive

San Jose, California 95134-1706

Cisco IOS Software, C2900 Software (C2900-UNIVERSALK9-M), Version 15.1(4)M5, RELEASE SOFTWARE (fc2)Technical Support: http://www.cisco.com/techsupport

Compiled Wed 18-Jul-07 04:52 by pt_team

Image text-base: 0x2100F918, data-base: 0x24729040

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

Cisco CISCO2901/K9 (revision 1.0) with 491520K/32768K bytes of memory.

Processor board ID FTX152400KS

2 Gigabit Ethernet interfaces

DRAM configuration is 64 bits wide with parity disabled.

255K bytes of non-volatile configuration memory.

249856K bytes of ATA System CompactFlash 0 (Read/Write)

--- System Configuration Dialog ---

Continue with configuration dialog? [yes/no]:

At this stage, either one can choose to continue with interactive session as shown above OR can opt for manual setup mode.

However, at this stage we don't know enough about Cisco ISO functionality, therefore we just type "no" and choose Command Line Interface (CLI) mode.

Press RETURN to get started!

Press Enter and we have the following screen in front of us.

Router>

With this prompt, we are now in User EXEC mode.
Now proceeding further, let's have a look on various operating modes of Cisco IOS which are as under:

1. User EXEC Mode

2. Privileged EXEC Mode

3. Global Configuration Mode

4. Interface Configuration Mode

5. Subinterface Configuration Mode

6. ROM Monitor Mode

At the moment, we are in user EXEC mode and in this mode we only very limited rights. Its only to view some basic things like ping, show, enable etc.

The last command (enable)is very important as this takes us to another very powerful mode of Cisco ISO, the privileged EXEC Mode.

Router> enable
Router#

So now we are in the Privileged EXEX mode. You can see the sign of ">" has been changed to "#". This is very important mode because in this mode we can not only view but change Router configurations.

From this mode, we can enter in next mode of operation, i.e., Global Configuration Mode by typing configure terminal or just config t

The commands in global configuration mode are called global command and they effect the entire router.

Router# configuration terminal
Router(config)#

The change in prompt is noticeable which has been changed from Router# (privileged mode) to Router(config)# (global configuration mode).

The router is there to provide and interface between the outside world and our own local area network. Therefore, it has interfaces to not only connect us for its configuration called console or auxiliary ports, but it also has other interface, for instance, serial interfaces to connect us to rest of the world's LANs.

To enter in the Interface mode of operation, interface command is used in global configuration mode. For example, to enter in the FastEthernet interface of the router, we proceed as follows.

Router(config)# interface FastEthernet 0/1
Router(config-if)#

We moved from global configuration mode to an interface mode, therefore the prompt changed from Router(config)# to Router(config-if)#

The physical interface of a router can further be divided logically into more than one virtual subinterfaces. The subinterface mode will be discussed later during discussion of frame relay

Finally, the ROM monitor mode is used when a Router is not able to find a valid system image then the ROM monitor mode helps to find a valid system image.

SETTING PASSWORD ON A ROUTER

The Internet age is full of threats from the individual wanting an unfair access to the routers. Therefore, Cisco routers are provided with multiple level of security using passwords.

1. Enable

2. Enable secret

3. Console

4. Auxiliary

5. Telnet

First two passwords are used in User EXEC mode to further restrict the access to the privileged EXEC mode and these are called Enable passwords.

The last three are called User mode passwords and these are used to prevent access to router IOS from console port, auxiliary port of through Telnet.

Enable password is set from global configuration mode as follows.

Router> enable
Router#
Router# configuration terminal
Router(config)#
Router(config)# enable password ITC

Enable Secret is set from global configuration mode as follows.

Router> enable
Router#
Router# configuration terminal
Router(config)#
Router(config)# enable secret ITC

User mode password are set in the global configuration mode with line command as follows.

Console password is set using line console 0 command

Router> enable
Router#
Router# configuration terminal
Router(config)#
Router(config)# line console 0
Router(config-line)# password console
Router(config-line)#login

Telnet passwords are set using line vty command in the global configuration mode as follows.

Router> enable
Router#
Router# configuration terminal
Router(config)#
Router(config)# line vty 0 15
Router(config-line)# password console
Router(config-line)#login

Auxiliary password is set using the line aux 0 command in the global configuration modes

Router> enable

Router#

Router# configuration terminal

Router(config)#

Router(config)# line aux 0

Router(config-line)# password aux

Router(config-line)#login

Secure Shell password is set using the line vty 0 15 command in the global configuration modes

Step-1:

Router(config)# hostname AnyName

Router(config)# ip domain-name AnyDomain.com

Router(config)# crypto key generate rsa

Router(config)# username AnyName password AnyPassword

Step-2:

Router(config)# line vty 0 15

Router(config-line)# login local

Router(config-line)# transport input ssh

Now check from any PC or other router by using the following command

C:\>ssh -l username IP_Addresss (Note -l is -L not -1)

IPv6

Global Routing Prefix: These are assigned at organization level. If an organization is assigned a Global Routing Prefix of, for instance, 2001:DB8:1111::/48, no other company can use any address whose first part matches 2001:DB8:1111::/48.

Link Local Address: They only work on local subnet, they do not leave IPv6 subnet.

ARP version of IPv6 (NDP) uses link-local address.
Link-local are used as next hop address.
Show IPv6 command lists only the link-local address of neighbors.

Dynamic Unicast Address Configuration

DHCP

Router(config)# interface AnyInterface

Router(config-int)#ipv6 address dhcp

SLAAC: