David’s Cisco Networking Blog

August 23, 2008  5:03 AM

Wheel of Fortune – Cisco style – IPrize

David Davis David Davis Profile: David Davis

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.

August 22, 2008  8:41 PM

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

David Davis David Davis Profile: David Davis

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.

August 22, 2008  5:39 AM

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

David Davis David Davis Profile: David Davis

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.

August 21, 2008  8:29 PM

Determining the Network ID using the Logical AND Operation

David Davis David Davis Profile: David Davis

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:
IP subnet mask:

The binary equivalent for IP address
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 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 For more information on TCP/IP Subnetting,
visit Appendix A: Subnetting an IP Address Space.

August 20, 2008  11:26 PM

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

David Davis David Davis Profile: David Davis

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.

August 20, 2008  5:14 AM

Four show commands to Verify the OSPF configuration

David Davis David Davis Profile: David Davis

show ip ospf – provides information about the OSPF process and its details.
show ip ospf database – provides information about the contents of the topological database.
show ip ospf interface – provides information on how OSPF has been configured on each interface.
show ip ospf neighbor – displays all the information  about the relationship that the router has with its neighbors.

August 20, 2008  5:06 AM

Doctors and Medical Staff go wireless thanks to Cisco

David Davis David Davis Profile: David Davis

We have come a long way from the age of Doctors coming to our homes in horse-drawn carriages. I recently read about Cisco’s healthcare solutions and was interested in how advanced their offering was. If you think about all the technology that goes into a hospital or doctor’s office, there is a ton of technology that makes that happen. Consider these applications:

  • Cisco wireless APs connecting doctor and nurse laptops and PDAs
  • Cisco wireless APs and switches connecting VoIP phones
  • Cisco switches connecting imaging devices for image devices like xray machines with 1GB or 10GB Ethernet
  • Routers transmitting patient data to the proper building or office
  • Network high-availability features like VRRP, HSRP, routing protocols, and STP keeping the WAN and LAN network up in case of failure – Cisco calls this”the medical grade network”.

There is really no more critical data than the data at a hospital as the patient’s lives are at stake. Additionally, HIPPA has also required and driven many of these technology updates.

Do you use Cisco in a healthcare environment? I am interested in hearing what applications you use – post your comments here.

For more information, please see Fulfilling the Promise of Mobile Medicine and Cisco’s healthcare industry solutions.

July 30, 2008  9:27 PM

Cisco’s new LearnNetSpace website has a lot to offer

David Davis David Davis Profile: David Davis

Cisco has unveiled a new web site – LearnNetSpace – to help us in a dedicated forum to share problems and helpful solutions that many of us have learned through trial and error. Networking with your peers is a great solution. I was just viewing the web site, and WOW, what a great place to share and be taught. There is information on CCNA, CCNP, and CCSP certification, study materials, blogs, discussions, etc. Be sure and check this one out.

For further information on this new opportunity for growth, please see the Cisco article, Cisco Boosts Worldwide Talent Development Efforts to Meet Increasing Demand for Networking Skills.

July 24, 2008  9:25 PM

Three show commands that will help you as a Cisco Admin

David Davis David Davis Profile: David Davis

Show version – This command lists information like the IOS filename and version currently in use. Another very important thing this command shows is the configuration register value The register value 0x2102 is the default factory value. You will need this value, for instance, if you do not know the password on your router. For more information on router passwords, please see my article, How to properly secure your Cisco router with passwords. For more information on the show version, please see the Cisco Use of the Configuration Register on All Cisco Routers documentation.

Show file information –  Similar to MS DOS, it displays file information about the specific file.
You must be in EXEC mode to use this command.
Example: Router1#Router# show file information tftp://gener/davis/c3300-d-a.b
tftp:// gener/davis/c3300-d-a.b:
type is image (a.out) [relocatable, run from flash]
file size is 8524596 bytes, run size is 9044940 bytes [8512316+112248+420344]
Foreign image

For additional information on the show file information command, see Cisco CFR Commands: show context — show ip http server documentation.

Show host – Display the IP addresses that the Domain Name Server (DNS) uses to resolve the host name.You must be in exec mode to use this command.
Example: R1#show host
name-server-one :
name-server-two :
domain-name : orchard
For additional information on the show host command, please see the Cisco show commands documentation.

July 24, 2008  9:23 PM

Can Cisco really change other businesses to help education?

David Davis David Davis Profile: David Davis

While Cisco has great networking and VoIP solutions, I wonder what they can do to really change other businesses…

According to the latest Cisco news, Cisco believes a transformation of educational systems is required, as well as improved teacher and leadership development. Cisco has met with district administrators, school leaders, teachers and community members to make sure that their new paradigm is heard loud and clear.  Our kids are our future and we should give them every technological opportunity to help them seek their full potential. For more information on this new concept, please see the Cisco article, Cisco Says Radical Shift in Education Systems Required to Sustain Global Competitiveness. 

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