August, 2008

How to put an IP address on an Ethernet interface

There are 4 easy steps to accomplish this task.  Remember that you will always need to access the global configuration mode to add interfaces. Let’s walk through these steps together.

First you should connect to your router. You would do this with the enable command.
router> enable            enter

Now we need to access the configurator to use the terminal.
router# config t            enter                 (Note: t for terminal)

Notice that the prompt changes as you go deeper into the router configuration. (> sign changes to # sign).

You should see the following message:
Enter configuration commands, one per line.  End with CNTL/Z.

Next we need to configure the Ethernet interface.
router(config)# interface Ethernet 0/0    enter

Notice that the prompt now changes to (config-if)# indicating that we are now in configuration interface mode.

The final step is to type the IP address and subnet for the ethernet interface.
router(config-if)# ip address 1.1.1.1 255.255.255.0

Pressing CNTL/Z saves your changes and gets you back to the enable prompt. Of course you will want to verify your configuration. Type the following command at the enable prompt:
router# show interface Ethernet 0/0   enter

You should see the Ethernet 0/o is up and the IP address that we configured is displayed.

Eight Decimal to Binary Conversions to memorize for CCNA certification

128 – 1000 0000
64  -   0100 0000
32  -  0010 0000
16  -  0001 0000
8  -   0000 1000
4  -  0000 0100
2  -  0000 0010
1  -  0000 0001

What effect could Internet access have for everyone around the USA?

It has been suggested that the United States only uses 5% of the Internet. There is so much untapped information that can be accessed but unavailable due to technology restraints. But, thanks to the latest article from Google’s co-founder, Larry Page on Google’s vision of “wi-fi on steroids”, it may be possible in the very near future to fully utilize the internet for personal use and to attract tourism to remote areas that previously were unavailable or unknown. That’s one of the many potential uses for the wireless spectrum that is now lying unused between TV channels, says Page. To put this in perspective, think about all the unused open sectors on your PC hard drive. Once they are identified and compressed, wow, it’s like your PC suddenly is in warp drive. That’s an analogy of the “white space” that is available on the internet but not being used. White space or spectrum sensing as it is called holds the promise of giving low income Americans the availability to access the internet via wi-fi wireless Mesh networking at a cost that can be affordable. It can be possible to hold a conversation while passing through a tunnel or on a subway using this technology.

Current internet providers need not worry. Personal/portable devices will continuously scan for TV and wireless microphone signals, both full and low-power TV licensees will be detected and avoided even if they change channel assignments in the future. If FCC give its approval for use of spectrum sensing, it will not be implemented until after the February 2009 transition deadline. Additionally, it will take time for manufacturers to build and for the FCC to test and certify the devices.  For additional information, please read the blog: Larry Page talks about Google’s vision of “wi-fi on steroids”.

Four OSPF Router designations and their responsibilities

OSPF Routers have different responsibilities depending on their position and functionality.  Let’s look at them-

The Internal Router – This router exists within an area. It’s responsible for maintaining a current and accurate database of every subnet within an area . It’s also responsible for forwarding data to other networks by the shortest path.

The Backbone Router – This router exists within the backbone area, also called Area 0.  On some routers, it’s also known as Area 0.0.0.0.

The Area Border Router – Also known as ABR, it’s responsible for connecting two or more areas. It holds a full topological database for each area to which its connected and sends LSA updates between the areas.

The Autonomous System Boundary Router – Also known as ABSR, is used to connect to a network or routing protocol outside the OSPF domain. This router should reside in the backbone area.

Seven Acronyms that will come in handy for CCNA certification

ABR – Area Border Router:  A router that has interfaces in many OSPF areas. For more information on ABR, visit: Managing Routers.

ARP – Address Resolution Protocol: ARP finds a hardware address, also known as Media Access Control (MAC) address, of a host from its known IP address. It maintains a table in which MAC addresses are mapped to IP addresses.  For more information on ARP, please visit: Configuring Address Resolution Protocol Options.

BGP – Border Gateway Protocol: Performs interdomain routing in TCP/IP networks.  For more information on BGP, please visit: Border Gateway Protocol – Introduction.

CLI – Command-Line Interface:  Cisco CLI The Cisco IOS command-line interface (CLI) is the primary user interface used for configuring, monitoring, and maintaining Cisco devices. It allows the user to directly and simply execute Cisco IOS commands, whether using a router console or terminal, or using remote access methods.  For more information on CLI, please visit: Using the Cisco IOS Command-Line Interface documentation.

DHCP – Dynamic Host Control Protocol: enables users to dynamically and transparently assign reusable IP addresses to clients.  For additional information on DHCP, please visit: Dynamic Host Control Protocol (DHCP)/Domain Name System (DNS) Introduction documentation.

DNS – Domain Name System: is the system in the Internet that maps names of objects (usually host names) into IP numbers or other resource record values.  For additional information on DNS, please visit: Dynamic Host Control Protocol (DHCP)/Domain Name System (DNS) Introduction documentation.

OSPF – Open Shortest Path First: Open Shortest Path First (OSPF) is a routing protocol developed for the Internet Protocol (IP) . It uses a metric of link cost which adds the costs of each link cost from a router, to a subnet to determine the shortest path. For additional information on OSPF, please visit: Open Shortest Path First (OSPF) Introduction documentation.

Wheel of Fortune – Cisco style - IPrize

Playing off the idea that the public loves game shows, Cisco has come up with an ingenious way of asking the public for help on a concept for its next $1 billion dollar business.  According to Guido Jouret, chief technology officer for Cisco’s Emerging Technologies group, “its down to 3 contenders” . Contestants have the potential of winning $250,000.00 and a chance to be part of the team that takes the idea from concept to reality. Ideas have come literally from around the world. We wanted people to think “outside the box” and while many good ideas were offered, Cisco had to keep its main objectives in mind which is - does it make sense for Cisco and can it potentially grow into a $1 billion dollar business. To view the entire article, please see I-Prize Contest Proving a Winning Approach to Discovering Billion-Dollar Business Ideas.

The three main Network Topologies and how they can work for you

Studying for the Cisco CCNA or CCENT? You will certainly run across networking topology questions. Here’s a quick review:

First of all let’s define what a topology is- Simply put, a topology is the layout of a network. There are really three basic types of topologies. They are Star, Bus, and Ring. Let me explain them to you.

Star – All computers and devices are connected to a centrally located hub or switch.  The hub or switch collects and distributes the flow of data within the network. It’s better to use a switch than a hub because a switch transmits the data to the intended recipient rather than to all hosts on a network.

Bus –  All computers and devices are connected in series to a single linear cable called a trunk or sometimes called a backbone. Both ends of the trunk must be terminated to stop the signal from bouncing back up the cable. Because the bus topology does not have a central point it is difficult to troubleshoot problems.  Also, a break at any point along the bus can cause the entire network to go down.

Ring – In this topology, all computers and devices are connected to cable that forms a closed loop.  Each computer on this type of topology acts like a repeater and boosts the signal before sending it to the next computer. It transmits data by passing a “token” around the network. Hence this type of network is commonly called a token ring network. Similar to the Bus topology, if one computer fails, the entire network goes down.

Of these three network topologies, the Star topology is the best network type and is based on the Ethernet standard.  For additional information on all of these topologies, please visit the Cisco Internetworking handbook - topologies section.

Could Cisco’s latest purchase announcement make working from home easier?

With gas prices going up, up, up and salaries virtually remaining the same, companies are looking for ways to help ease the pain at the pump. Cisco has unveiled its intention to buy a Seattle based company, Pure Networks, which is a leader in home networking software. Working from home will become even easier to connect and enable to various tools as if you were sitting at your office. To view the entire article, please see Cisco Announces Definitive Agreement to Acquire Pure Networks.

Determining the Network ID using the Logical AND Operation

Studying for your CCNA? Having trouble with IP Subnetting?

It’s all about the 1’s and 0’s. We just need to convert our IP address and Subnet mask into binary and then subtract the ones from the zeros. 1+1 = 1, 1+0 = 0, 0+1 = 0. It really is that easy.

Let’s find out what the network ID is for this example.
IP address:          140.12.26.128
IP subnet mask: 255.255.240.0

The binary equivalent for IP address 140.12.26.128:
140 decimal is 10001100
12 decimal is    00001100
26 decimal is    00011010
128 decimal is 10000000
The binary for this IP address is:  10001100.00001100.00011010.10000000

Now let’s look at the binary equivalent for the IP subnet mask 255.255.240.0:
255 decimal is 11111111
255 decimal is 11111111
240 decimal is 11110000
0 decimal is      00000000
The binary for the subnet mask is:  11111111. 11111111. 11110000. 00000000
You have two steps left to complete. Subtract the binary IP address from the binary subnet mask
And then convert it to decimal.

Binary IP Address:         10001100.00001100.00011010.10000000
Binary subnet mask:     11111111. 11111111. 11110000.00000000
====================================
Binary Result                  10001100.00001100.00010000.00000000
Decimal result:                    140.             12.            16.              0

Your Network ID for this IP/subnet is 140.12.16.0. For more information on TCP/IP Subnetting,
visit Appendix A: Subnetting an IP Address Space.

How can Cisco Automatic Signature Extraction prevent zero-day virus attacks?

The Cisco IOS is powerful and already running on your routers. You would think that it could play a part in this virus detection and prevention, right? In my latest TechRepublic article, learn how Cisco Automatic Signature Extraction can help to prevent zero-day virus attacks. This is a new feature that works with a Linux server as a collector of the signatures. That “collector” communicates back to the routers to block the malicious traffic. Currently, the collector is in limited release and you have to contact your Cisco rep to obtain it. Still, I think this feature has a lot of promise for the future.