How the Traceroute Works, Understanding Traceroute Output and Troubleshooting

How the TRACEROUTE Command Works

The traceroute command is used to discover the routes that packets actually take when traveling to their destination. The device (for example, a router or a PC) sends out a sequence of User Datagram Protocol (UDP) datagrams to an invalid port address at the remote host.

Three datagrams are sent, each with a Time-To-Live (TTL) field value set to one. The TTL value of 1 causes the datagram to "timeout" as soon as it hits the first router in the path; this router then responds with an ICMP Time Exceeded Message (TEM) indicating that the datagram has expired.

Another three UDP messages are now sent, each with the TTL value set to 2, which causes the second router to return ICMP TEMs. This process continues until the packets actually reach the other destination. Since these datagrams are trying to access an invalid port at the destination host, ICMP Port Unreachable Messages are returned, indicating an unreachable port; this event signals the Traceroute program that it is finished.

The purpose behind this is to record the source of each ICMP Time Exceeded Message to provide a trace of the path the packet took to reach the destination.

CCNA Exploration

Are you a Novice to Networking? Started your studies for Cisco Certifications, CCNA? Here is another good tool to use for preparing your CCNA Exam. This course starts from Very Basic things in comprehensive detail to the advanced topics that can cover some of the topics you will find in CCNP, that mean it prepares you not only for CCNA but also starts your studies for CCNP. I have to give you some brief intro of CCNA Exploration, show to those who don't know about it and are preparing for CCNA Certifications, to get this great tool go and google CCNA Exploration.

Here is some brief officialy intro of CCNA Exploration.

The Cisco CCNA® Exploration curriculum provides a comprehensive overview of networking; from fundamentals to advanced applications and services. It is based on a top-down approach to networking that is popular in many colleges and universities. This course emphasizes theoretical concepts and practical application, while providing opportunities for students to gain the skills and hands-on experience needed to design, install, operate, and maintain networks.

CCIE professionals average Salary

Employees with a Cisco Certified Internetwork Expert (CCIE) Certification median Salary by Job.

This Graph is updated automatically, so whenever you see it, it is Updated

Median Salary by Job - Certification: Cisco Certified Internetwork Expert (CCIE) (United States)

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New Cisco Security Specialist Certifications

Cisco introduced new Security Specialist certifications to recognize individuals who have attained specific competencies critical to meeting demand for network security skills that align with evolving job roles, technologies and business requirements.

The combination of new security threats, regulatory compliance mandates, and the need to protect customer and organizational data has driven the demand for a more efficient use of network security technologies within architectures such as Smart+Connected Communities. The increasing complexity of network security responsibilities with mobility, social networking, voice, video, virtualization, cloud computing and physical safety and security requirements is driving greater specialization and advanced skills on the products that facilitate these solutions, including virtual private networks, firewalls, authentication and intrusion prevention. According to a recent survey of the Cisco® CCIE® community, security and risk management will be the networking skills in greatest demand by businesses over the next five years.

Overview and New Development in Cisco Certifications

New Developments in Cisco Certification

Cisco training and certification enables network professionals to demonstrate mastery of current Cisco products and solutions. In the past four years, the Cisco Career Certification Program has updated its certifications to meet market demand. Changes include:

• New CCAr (Cisco Certified Architect) certification, the highest level of Cisco certification available.
• Revised CCNP (Cisco Certified Network Professional) training and certification.
• New Service Provider Operations track. 

Why Ethernet is Called ETHERNET

Do you have question that why the word Ethernet is called Ethernet? and what is the Origin of Word Ethernet?

Here is the brief history that why Ethernet was named as ETHERNET.

In late 1972, Metcalfe and his Xerox PARC colleagues developed the first experimental Ethernet system to interconnect the Xerox Alto, a personal workstation with a graphical user interface. The experimental Ethernet was used to link Altos to one another, and to servers and laser printers. The signal clock for the experimental Ethernet interface was derived from the Alto's system clock, which resulted in a data transmission rate on the experimental Ethernet of 2.94 Mbps.

Ten Free Antivirus Utilities

The cost of anti-malware apps keeps rising. Luckily, there are effective tools you can use to prevent and remove infections without spending a dime.

Over the last few years, anti-malware software has become increasingly costly. But there are still ways to protect your computer for free. Below are listed, Ten free utilities you can use to either prevent malware infections or to help clean up the mess once a PC becomes infected.

1: AVG Anti-Virus Free Edition 2011
 AVG’s free antivirus and although it isn’t perfect, it seems to be at least as good as most of the commercial anti-malware products. AVG’s free edition provides basic protection against viruses and spyware, but the company also offers a more comprehensive security suite called AVG Internet Security 2011. This suite offers the same anti-malware protection as the free edition, but it also provides real-time protection against Internet search and social networking sites.

What is Multicast and its Uses

Introduction

When multiple receivers are required to get the same data at approximately the same time, multicast is a more efficient way of delivering data than unicast.

A unicast packet has a single source IP address and a single destination IP address. Data will be delivered to a single host. A multicast packet has a single source IP, but it has a multicast destination IP address that will be delivered to a group of receivers. The advantage is that multiple hosts can receive the same multicast stream (instead of individual streams), thereby saving bandwidth.

For example: Let’s say that I want to download an instructional video from an FTP server at work. I plan to do this at lunch time so that I can view the video while I eat my lunch. This would be a unicast delivery: A single receiver (me) and a single source, the server. Now let’s say that I tell 49 of my co-workers of my plan, and they decide that they would like to watch this video at lunch time as well. If we all downloaded this video individually, it would be a total of 50 unicast streams. It seems like a waste of bandwidth doesn’t it? If the compressed video takes approximately 1.5 mbps of bandwidth per stream, and you multiply that times 50, it would equal 75 mbps being consumed by one video! Wouldn’t it make better use of network resources if this video could be viewed as a multicast application and all 50 employees could watch the video stream at the same time? Instead of using 75 mbps of bandwidth, we would be using 1.5 mbps and accomplishing the same goal: We’d all be getting raises in two weeks or less!

Nine Things to Troubleshoot your network

Do you work for a small organization where, you are the network admin for PCs and your routers and switches. Anything that’s broken is YOUR problem and only your fault!
Here are the basic Nine Things to know to troubleshoot your network 

1. Physical Layer Verification

One of the first things you should do it to check the cable. Do you have a green light at the back of your ma­chine?

2. Network Layer Verification

After Verifying Physical Layer that the cable is plugged in, ensure that there is an IP address assigned on the system.

You can go to the command prompt and checking the IP address using the “ipconfig” command. You want to make sure that you see that the IP address/subnet mask that are assigned are correct for that segment.

For Cisco routers, the command show interface will show you the IP address and subnet mask. So, please, consult your documentation for the systems you are working on.

What is Cloud Computing

Are you puzzled with the new IT Term, the Cloud Computing. What is it and what for cloud computing is?

Watch the Video for very brief and comprehensive Introduction of Cloud Computing... 

Limit bandwidth on a Cisco Catalyst switch port

Why Should You limit the Bandwidth?

There are a number of reasons for limiting bandwidth on a Cisco switch Ethernet port. (Of course, the port speed of the switch port always poses an ultimate limitation.)

For example, let’s say you work for an Internet service provider in a collocation facility, and you sell access to the Internet in 1-Mb increments. The switch port in question is 100-Mb full duplex. In this case, you would limit the end device connected to that switch port to whatever 1-Mb increment the customer has paid for.

This is just one example of how this configuration could be useful, but there are many other possibilities. Let’s look at the commands used to create this bandwidth limit on a Cisco switch.

Cisco Collaboration Workshops

Discover how you can help your organization enhance collaboration not only with its current technology investments, but also by leveraging the new tools and devices available to users within the workplace.

Join Cisco experts as they host the next Cisco Interactive Technology Workshop using Cisco WebEx conferencing. During this event attendees will have the opportunity to gain a deeper technical understanding of Cisco solutions, interact with Cisco experts, have questions answered live, and see a live product demonstration.

IPv4's finale 'one of the most important days of the Internet'

Internet policymakers officially handed out the last five blocks of IPv4 address space to each of the Regional Internet Registries (RIRs) at a ceremony held in Miami, feb 03, 2011.

BACKGROUND:

The ceremony marked the depletion of the free pool of addresses for IPv4, the main communications protocol that underpins the Internet. The ceremony's goal was not only to celebrate this historic milestone in the Internet's 40-year history, but also to demonstrate that this precious resource of IPv4 addresses was doled out in an equitable fashion around the globe.

Policymakers -- including the Internet Assigned Numbers Authority (IANA) and the Internet Corporation for Assigned Names and Numbers (ICANN) -- used the ceremony to underscore the need for network operators and content providers to migrate to IPv6, the long-anticipated upgrade to IPv4.

How to design small-to-medium sized Cisco Networks

Network Design or Achitecture Guide of Cisco router switches firewall