David’s Cisco Networking Blog

September 22, 2008  6:38 AM

Cisco to buy instant messaging company – Jabber

David Davis David Davis Profile: David Davis

Cisco’s access to the technology necessary to provide a complete instant messaging & presence tracking solution is complete. Today, Cisco purchased Instant Messaging company, Jabber.

Cisco aims to be #1 in the communication & collaboration business. To do that, they needed what Jabber had – an enterprise messaging product that would scale well, had strong presence features, and supported open standards. Jabber’s XMPP is used by GoogleTalk and Jabber is one of the pioneers in IM and presence.

Jabber is based in Denver and Cisco didn’t disclose the financial detail of their purchase. The acquisition is expected to be completed by the first half of 2009.

Cisco just completed PostPath, Inc, an e-mail and calendaring company.

What’s this mean to you? We should all be on the lookout for the result of Cisco’s acquitisitons – a powerful collaboration and communication tool for “the masses”.

You can learn more about Jabber at their homepage and/or read about Cisco’s official announcement that they are buying Jabber.

September 17, 2008  1:27 AM

What is AAA and how do you configure it in the Cisco IOS?

David Davis David Davis Profile: David Davis

Whether you are studying for the Cisco CCNA, CCNP, Cisco Security certifications, the Security+, or the CISSP, you must understand AAA.

AAA is authentication, authorization, and accounting.

Learn about AAA as it relates to Cisco routers and switches, and how to configure it in the Cisco IOS by reading my new article What is AAA and how do you configure it in the Cisco IOS?

September 15, 2008  1:23 AM

Monitor Cisco routers and switches using the IOS environment command

David Davis David Davis Profile: David Davis

How do you know what the temperature is where your router or switch is? This can tell you if the device is overheating due to fans being out or improver ventilation in the room where the Cisco device is. Additionally, you would want to know if the fans were running and what their speed is. Oh yeah, and what about the status of your power supplies?

You can find out all this and more using the Cisco IOS show environment command. You can also configure the switch or router to alert you when there is an environmental alarm.

To see how it is done,  read my article Monitor Cisco routers and switches using the IOS environment command

September 8, 2008  5:07 AM

Virtual conferences rooms – almost like being face to face

David Davis David Davis Profile: David Davis

Cisco has uniquely cornered the market on tele conferencing with the introduction of Cisco TelePresence.  Many companies are utilizing this feature to save on time and travel but are still getting the work done. It has value added to it by ease of operation and you don’t have to add new infrastructure to your network to use it.  “Cisco Telepresence gives us the experience and benefit of actually being in the room with colleagues on the other side of the world, without having to pack a suitcase.”, says Chief Information Officer Ken Henry of HSBC. And of course, Cisco is preserving our future environment by having companies use less travel and therefore less carbon dioxide in the air.  For further information on this article, please see my article on TelePresence at:   What is Cisco Telepresence and what does it take?

September 5, 2008  5:02 AM

Four Routing Protocols that you should know

David Davis David Davis Profile: David Davis

BGP: Border Gateway Protocol –  As defined in RFC 1771, BGP is an interdomain routing protocol. You would use BGP to exchange routing information between autonomous systems. It’s usually configured between two directly connected routers that belong to different autonomous systems and the routers must first become established neighbors. TCP Port 179 is reserved for the BGP protocol to establish connections with neighbors. For more information on BGP, see the article on Border Gateway Protocol documentation.

MBGP: Multiprotocol  Border Gateway Protocol – Bigger and better BGP. MBGP is an enhanced form of BGP which has IP routing information about other protocols. It also carries information about reachable and non-reachable destinations in the network layer (that’s Layer 3). For more, information, please see the MBGP article.

EIGRP: Enhanced IGRP  –  Just like MBGP is an enhanced form of BGP,  EIGRP provides  more compatibility than IGRP. EIGRP allows IGRP routes to be imported into EGRP, and vice versa, so it is possible to gradually add it into your existing IGRP network. For more information, see the EIGRP article.

RIP: Routing Information Protocol – A distance-vector protocol that uses hop count as its’ metric. This metric can be hops, bandwidth, delay, or multiple metrics.  Distance vector protocol periodically sends the neighboring routers its entire routing table to ensure network availability. RIP is used for routing traffic and is an interior gateway protocol (IGP), which means that it performs routing within a single autonomous system.  Just like IGRP, this is an old routing algorithm and could result in split horizon. For more, information, please see the RIP article.

August 25, 2008  9:19 PM

How to put an IP address on an Ethernet interface

David Davis David Davis Profile: David Davis

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

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.

August 25, 2008  9:18 PM

Eight Decimal to Binary Conversions to memorize for CCNA certification

David Davis David Davis Profile: David Davis

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

August 25, 2008  5:16 AM

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

David Davis David Davis Profile: David Davis

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”.

August 24, 2008  9:15 PM

Four OSPF Router designations and their responsibilities

David Davis David Davis Profile: David Davis

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

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.

August 23, 2008  9:08 PM

Seven Acronyms that will come in handy for CCNA certification

David Davis David Davis Profile: David Davis

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.

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