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Spanning Tree Protocol (STP) is dead, or at least it should be. It’s too slow to converge when there’s a change, and it causes issues with performance because there is only one forwarding path. It was developed in 1985 by Radia Perlman at Digital Equipment Corporation to allow for redundant paths within a Layer 2 topology, which was great in 1985. In fact, it was huge! So much so, that it was later standardized by the IEEE as 802.1D, and we’ve been living with it ever since.

The short answer (and a common one in our industry): it depends. When comparing Cisco IOS with Juniper Junos, the decision to choose one over the other is difficult and often boils down to cost. Of course, there are other factors to consider.

In my last post, we learned that the Dynamic Host Configuration Protocol (DHCP) is a computer networking protocol used by hosts, identified as DHCP clients, to retrieve IP address assignments and other configuration information. DHCP uses a client-server architectur...

This is another topic of heated debate, and it changes from network to network, but I found a simple approach that works in most cases. Since I have four queues and four classes of traffic, I need to categorize my important traffic into four classes. Strictly for explanation purposes I took some liberty in defining four categories of traffic that are very effective in both large and small networks. These classes are: Real Time Protocol (RTP), Network Management (NetMgt), Business Critical, and the Default.

With the advent of video use in our everyday communications, a number of questions commonly surface. One of them is the question of terminology. What's the difference between video conferencing and telepresence? What is meant by immersive technologies? Frankly, there is no one single right answer.

The most obvious difference is that hubs operate at Layer 1 of the OSI model while bridges and switches work with MAC addresses at Layer 2 of the OSI model. Hubs are really just multi-port repeaters. They ignore the content of an Ethernet frame and simply resend every frame they receive out every interface on the hub. The challenge is that the Ethernet frames will show up at every device attached to a hub instead of just the intended destination (a security gap), and inbound frames often collide with outbound frames (a performance issue).

The Cisco UCS is truly a “unified” architecture that integrates three major datacenter technologies into a single, coherent system: Computing Network Storage Instead of being simply the next generation of blade servers, the Cisco UCS is an innova­tive architecture designed from scratch to be highly scalable, efficient, and powerful with one-third less infrastructure than traditional blade servers.

Learn about the five types of area networks.

That depends on their configurations. For example: While it makes very good sense to include redundant physical links in a network, connecting switches in loops, without taking the appropriate measures, will cause havoc on a network. Without the correct measures, a switch floods broadcast frames out all of its ports, causing serious problems for the network devices. The main problem is a broadcast storm where broadcast frames are flooded through every switch until all available bandwidth is used and all network devices have more inbound frames than they can process.

According to Cisco marketing, Dynamic Multipoint VPN (DMVPN) “will lower capital and operation expenses, simplifies branch communications, reduces deployment complexity, and improves business resiliency.” Okay. But what is it, really, and why should we care?

The key difference between hubs, switches and bridges is that hubs operate at Layer 1 of the OSI model, while bridges and switches work with MAC addresses at Layer 2 of the OSI model.

Software-defined networking (SDN) is a solution that will enable your organization to meet the demands of network programmability and automation. The result will be greater network agility to support new applications while complying with increasing security needs.

Global Knowledge Course Director and Lab Topology Architect Joey DeWiele, a specialist in Unified Communications, discusses Cisco Unity, Unity Connection & Unity Express.

In the previous post, we discussed the need for VXLAN in the cloud along with the issues it solves. In this post, we will focus more on how VXLAN works.

There are some common misconceptions on the part of some of my students as to how VPN sessions are established from either a remote location or remote user to the ASA firewall. In particular, a “gray area” seems to be when the attributes from the tunnel group are app...

There are many interesting new issues that seem to have come with the addition of voice and video to the data network. Most of the engineers that are now working on VoIP networks come from either a pure data network background or a traditional phone system background...

When properly utilized, VLANs and trunks provide flexibility, stability and ease of troubleshooting. This paper provides technical details about VLANs and trunks, along with design options at a basic to intermediate level. Recommendations and commands are included throughout.

RTMT provides a set of canned views of both system resources and application counters that provide you with a snapshot of your environment right out of the box. Read on to learn how you can make RTMT even more helpful by customizing it to show you different views of your resources and CUCM environment.

Occasionally as I'm teaching a Cisco training class, I get an idea for a blog post and it happened again this week. The Securing Networks with ASA Fundamentals curriculum is mostly based on the Adaptive Security Device Manager (ASDM). While the class describes the us...

So far, in our discussion of Router Information Protocol (RIP), we’ve discussed the basics and also verified and reviewed RIP version1. We stated that RIP version 1 is a classful routing protocol that used FLSM and sent it routing updates without the subnet mask.  In...

Next Hop Resolution Protocol enables businesses to have a way for next-hop servers and next-hop clients to communicate with each other directly, bypassing a central hub and preventing potential bottlenecks.

The responsibility for securing organizational data has spread beyond the traditional IT professional. While there are more diverse security solutions, there are more diverse and sophisticated security threats. Security awareness and training is essential for everyone within an organization. Learn how Cisco has continued to evolve its security solutions and training.

Where should you apply the CSS, and why are there two places to apply it? One approach is to pick one of the parameters and apply the permissions there. Quite often, an administrator will pick the phone-level CSS and configure it there so that it applies to all calls made from all lines. The goal is to specify what partitions are allowed to be called. 

John Barnes, Global Knowledge's Cisco Course Developer, discusses enhancements to our UCS Troubleshooting Boot Camp and suggestions for students in preparation for this course.

Last blog we looked at how we can use Trunk groups to ease the configuration of dial-peers and digit manipulation using analog FXO ports for an E911 solution. Now let’s take a look on how it can be used for T-1 CAS configurations and ISDN channel selection. The firs...

One aspect of Unified Communications is this concept of trunk groups.  I will discuss what they are, what benefit they can provide and how to configure them for Cisco gateways. First of all the official definition of a trunk group is “A group of trunks serving the s...

Global Knowledge subject matter experts predict the top trends for 2020 in IT training, Microsoft, Cisco, AWS, cybersecurity and more.

Managers are in dire need of cybersecurity professionals with specific skills. If you’re looking to advance your career, or transfer into the cyber field, now is the time to get certified.

Discover the top 5 highest-paying and popular Cisco certifications from the IT Skills and Salary Report. Learn how to get certified and unlock IT career opportunities.

IT is a very fast changing industry – what is hot today may be a tiny niche market in only a few years and lesser known things may turn out to be huge trends. That having been said, there are many certifications that will be around for a long time. However, this does not imply that recertification and/or continuing education credits are not required to maintain certification. Predicting the future is always challenging, including in IT, but these certifications are good bets.

I recently came across an opportunity to use a relatively new feature in Cisco Unified Communications Manager (CUCM). Suppose you are the telecom administrator at a community hospital. During business hours, the Facilities Department is staffed and team members simpl...

One command that had a fairly long history first with the PIX Firewall and now the ASA is the shun command. In this post we’ll examine this command’s history, why it’s useful, and its new-found resurgence in threat detection implementation.

If you’re in IT, you’ve likely heard the saying, “In technology, the only thing constant is change itself,” and boy is that right! For technical companies, if you are not moving forward, then you’re falling behind. There is no such thing as standing still! A perfect example of this mindset is in Cisco’s evolution of video conferencing and telepresence.

In light of the recent tragic events in Haiti, it might be a good time to review some of the requirements for a well designed Uninterruptible Power Source (UPS) to be included in all of our critical network installations. As a CCNA, we are called upon to help maintai...

Interior Gateway Routing Protocol (IGRP) was a Cisco-proprietary Distance-Vector (D-V) classful routing protocol - basically an improved version of RIPv1. Like other D-V protocols, each IGRP router periodically flooded its routing table, but it differed from RIP in two ways. First, RIP’s advertisement interval was thirty seconds but IGRP’s was ninety seconds, which allowed IGRP to scale to larger networks than RIP. Second, RIP used a simple hop count metric, but IGRP’s more sophisticated metric was based on minimum path bandwidth and total path delay, with options to include link reliability and interface loading.

In 2013, Cisco released their Software Defined Networking (SDN) solution for the data center known as Cisco Application Centric Infrastructure (ACI). For many years, the networking industry has been asking for an approach to configuring networking devices more efficiently than having to individually configure each and every router and switch.

Moving data from one networked device to another requires several different functions. Each function has its own protocol or protocols that define how it is accomplished. Also, the process of delivering data from one device to another can vary. The main factor in data delivery is determining whether the two devices are directly connected or remotely connected.

Moving data from one networked device to another requires several different functions. Each function has its own protocol or protocols that define how it is accomplished. Also, the process of delivering data from one device to another can vary. The main factor in data delivery is determining whether the two devices are directly connected or remotely connected.

Like it or not, Internet of Things (IoT) is upon us. There are a number of factors that will impact its adoption rate, and the inevitable privacy (or lack of) discussions will likely happen sooner than later. This is going to change the world as we know it, in many cases for the better. But we will need to keep an eye on the extent to which it invades our personal lives if it is going to be the positive force it has the potential to be.

Cisco Access Control Lists (ACLs) are used in nearly all product lines for several purposes, including filtering packets (data traffic) as it crosses from an inbound port to an outbound port on a router or switch, defining classes of traffic, and restricting access to devices or services. Knowing how to design, configure, and troubleshoot ACLs is required for all network engineers working within a Cisco network.

While the Internet uses IP addresses assigned by an Internet authority such as the American Registry for Internet Numbers (ARIN), there are too few of these numbers to uniquely identify the millions of computers and computing devices in the world. Therefore, most enterprises use private addresses which allow them to identify the aforementioned computers. Of course, these IP numbers cannot be allowed on the Internet because all private networks use the same ones so there would be vast overlapping of addresses, and the addresses are not compliant anyway. Therefore, it is necessary to change the identity of a private host to a legal public host. This process is called Network Address Translation (NAT) and may be implemented on Cisco firewall products and Cisco routers. The firewall device(s) at the Internet demarcation point is by far the more popular way to implement NAT, but routers are used in small offices or small-to-medium-sized networks in which a separate firewalling solution is not possible or affordable. The focus of this paper is on the router-based NAT solution.

As IT departments struggle with skills gaps and businesses attempt to recovery economically from the COVID-19 pandemic, these 10 IT skills are essential to drive success. Job roles in these areas pay well, but decision-makers are struggling to find qualified candidates. If you’re looking to make an IT skills investment or start a new career path this year, these are the areas to consider.

Telepresence is a set of technologies that allow video conferencing in such a way that the user feels as if they are actually at the remote site. Cisco sells a variety of platforms in the telepresence space supporting up to three 65” high definition video displays,...

Switches play a vital role in moving data from one device to another. Specifically, switches greatly improve network performance, compared to hubs, by providing dedicated bandwidth to each end device, supporting full-duplex connectivity, utilizing the MAC address table to make forwarding decisions, and utilizing ASICs and CAM tables to increase the rate at which frames can be processed.

Instructor John Harmon continues his explanation of subnetting by showing how subnet masks can be used to sub-divide networks.

Instructor John Harmon explains subnetting using binary numbers and decimal conversions.

You may have noticed that it’s the dynamic routing protocols that get all the glory. Since I like rooting (routing?) for the underdog, let’s talk about static routes! As you may recall, a router has three methods for learning a route. A route can appear in the routi...

Subnetting is a complicated topic that has confused students for a very long time. However, subnetting is an important topic for many different certifications with various vendors, including Cisco. In the real world environment, people are used to just punching in the numbers in many of the free subnet calculators that are readily available on the internet. For exam purposes, you still have to do this in a very fast manner since many exams are time-based and you don't have the luxury of spending those precious minutes on any single question. This Cisco training whitepaper will solve some of those age-old and complicated subnetting puzzles.

Certifications are the most common way in IT to prove you have the skills to solve various technical and business challenges. In this article, I'll address a range of skill sets. For each certification listed, I've included what the certification measures, the requirements to obtain it.

Take charge of your Cisco network devices with Python programming As a network engineer, you might wonder why there’s any need for you to learn Python. After all, network automation is clearly where the industry is headed. And there are many tools that allow yo...

Internet Protocol (IP) routing protocols have one primary goal: to fill the IP routing table with the current best routes it can find. The goal is simple, but the process and options can be complicated. Routing protocols define various ways that routers chat among th...

According to the OSI layer concept, routing, or best path selection, takes place on Layer 3 and is based on the logical address. In this post, we want to discuss some of the points in that statement.

According to the OSI layer concept, routing, or best path selection, takes place on Layer 3 and is based on the logical address. In this post, we want to discuss some of the points in that statement.

In the previous discussion on QoS, the uses of Per-Hop Behaviors DiffServ to mark packets were identified and discussed in detail. Today’s post will identify the mechanisms to implement QoS. The five main categories of tools used to implement QoS are as follows. Cl...

Learn how to calculate QOS Bandwidth Percent vs Bandwidth Remaining Percent using a Cisco-defined formula. Read on for answers and examples from the experts at Global Knowledge!

In this hour-long webinar, Global Knowledge instructor John Barnes will guide you through implementing Cisco private VLANs. He will review VLANs and 802.1q, and he will discuss private VLAN fundamentals and operation, covering primary VLANs and secondary VLANs. He will cover VLAN mapping and discuss using private VLANs between multiple switches. He will also provide a use case example.

Global Knowledge Course Director and Lab Topology Architect Joey DeWiele, a specialist in Unified Communications, explains presence.

What is PBR? Policy-Based Routin (PBR) is the process of using a route map to match on something more than the destination and then defining the path out of the router based on those conditions. PBR could match on destination only, but typically we would match on more. PBR is considered to be an exception to the RIB and is looked at before examining the RIB.

Policy-based routing (PBR) provides network administrators with agility and flexibility to better manage traffic. With carefully architected policies, you can optimize how segments of your network process data, as well as how bandwidth is managed for business-critical applications.

The Global Site Selector (GSS) leverages the Domain Name System (DNS) to provide clients with reliable and efficient content services. Domain to IP address mapping is performed with consideration for availability, location, and load of content servers. Using the GSS in combination with Cisco’s Content Services Switch (CSS), Cisco’s Catalyst 6000 Content Switching Module (CSM), or Cisco’s Application Control Engine (ACE) allows users to create Global Server Load Balancing (GSLB) networks.

Understand the Cisco Security technology and certification training portfolio. This overview will cover the courses needed to prepare for the CCNA Security and CCNP Security certifications. You will also learn about recommended skills-focused courses covering SourceFire technologies, the ASA security solution, and the ISE access control and authentication platform.

Understand the Cisco Collaboration technology and certification training portfolio. This overview will cover the courses needed to prepare for the CCNA Collaboration and CCNP Collaboration certifications. You will also learn about recommended skills-focused courses covering basic and advanced Unified Communications Manager administration.

A video covering our Cisco Unified Communications courses - ACUCW1 & ACUCW2 - by Global Knowledge Course Director and Lab Topology Architect Joey DeWiele, a specialist in Unified Communications.

Now that we are moving towards IPv6, the logical move would be to also run OSPF for that protocol suite, which makes sense and reduces the learning curve for implementation and support. But, that would mean that you have to run two OSPF processes — one for IPv4 unicast and one for IPv6 unicast. That means two sets of policies have to be applied, including security for OSPF itself. Running OSPFv3 for both IPv4 and IPv6 reduces the number routing protocols and the configuration that goes with that. It makes it easier to implement policy in a consistent way for both protocol suites.

As cybersecurity threats continue to be a top concern facing organizations today, the Information Technology (IT) Governance team must stay abreast in assuring that the organization is protected. The IT Governance team must continually evaluate the risks to the organization and put in place Processes, Procedures and Technologies to protect the assets of the organization.  

Looking ahead at new and emerging certifications provides insight into the areas deemed valuable in the IT industry. If you are an early adopter or in a position where you need to show that you have the bleeding-edge expertise of a technology, this list of recent and upcoming certifications is for you. 

Find out what changes have been made and how you now have multiple paths to success with the help of Cisco Certification 2020! The new set of certification exams launched on 24th February. It provides a common language for software developers and networkers to bring the two together. The certification programme will also open-up a brand new horizon of job roles and skill sets that are already starting to emerge. Announced at last year’s Cisco Live event in San Diego, the new DevNet certifications aim to help professionals combine infrastructure expertise with programming to take advantage of the possibilities of intent-based networking. Changes to the Cisco certification programme also include new training and certifications in five key technology tracks. In the traditional Cisco network programme, the certifications range from the associate level to the expert level. The new certification involves a DevNet Associate, a DevNet Professional and soon there will also be a DevNet Expert certification. In this one hour webinar, John Berry discusses what’s new in Cisco Certification, what the professional of the future should look like and how to prepare technology professionals for new roles as a network automation developer.

Find out which OSI layer is concerned with reliable end-to-end delivery of data - and more. Get answers to your OSI reference model and network layer questions here.

ASA and PIX software version 7.0 introduced the configuration command nat-control which didn’t exist in previous versions of code. Although training course material for both the SNAF (Securing Networks with ASA Fundamentals) and SNAA (Securing Networks with ASA Advan...

Multicast Sparse Mode and its derivatives are supported in the Nexus OS. This white paper explains how it has been implemented in the Nexus platform to provide optimum performance in both virtual PortChannel and FabricPath environments.

While there are differences between the IP Multicast configuration in the IOS and the Nexus OS, the Protocol Independent Multicast (PIM) protocol remains fundamentally the same. If you feel comfortable configuring Multicast in the IOS, you should be able to acclimate fairly easily to the changes in the Nexus OS.

While cybersecurity remains the most popular certification category in our IT Skills and Salary Report, foundational-level certifications highlight our list of the most popular IT certifications of 2020. 

According to the Global Knowledge IT Skills and Salary Report, women make up 16% of the tech workforce, and an even smaller percentage (8%) are at the senior or executive level. Here’s an overview of the most popular and most pursued certifications by women in tech.

An quick fundamental overview of layer two devices.   To learn more about this and similar topics, enroll in our exclusive Understanding Networking Fundamentals course.    

Routers and switches make up the bulk of the network infrastructure and are vulnerable to attack. In a previous article, I talked about some of the different ways of hardening your network devices. In this blog, I’d like to specifically examine the routing protocols used on the major Cisco network operating systems.

Regardless of your vendor preference or your experience on the Juniper JUNOS CLI, assuming you have a point of reference to another vendor, your first thought when experiencing JUNOS is, “I have been here before.” The CLI is familiar, convenient, and polished. The similarities between JUNOS CLI and another CLI such as Cisco’s IOS are not what I want to focus on here however; it is their differences I want to focus on. But first, when you connect to a JUNOS powered device and access Operational Mode (see Brad Wilson’s blog post Introduction to Juniper Junos), it looks very much like the User EXEC Mode in IOS. In fact, there are a lot of JUNOS commands that are very much like the IOS User EXEC Mode commands.

Cisco Internetwork Operating System (IOS) has been around since a little after the inception of Cisco Systems as a company. In 1984, Len and Sandy Bosack from Stanford University founded Cisco Systems with a small commercial gateway server. The first Cisco router that I touched was an Advanced Gateway Server (AGS), which was the first marketed product of the company. After this came the Mid-Range Gateway Server (MGS), the Compact Gateway Server (CGS) and later the Integrated Gateway Server (IGS) and AGS+. The first version of IOS that I touched was 8.2(7). The operating system was based on a Unix-based system and was designed as a monolithic operating system, meaning that processes are stacked and interrelated.

The first big push toward implementation of IPv6 was mobile devices. Now, one of the driving forces is the Internet of Things. As the name implies, this means everything, including machine to machine communication (M2M).

None of us have much time to waste, so what can you do when your environment changes quickly and you need to come up to speed on a device that you have never seen before? You find the quickest way to bring yourself up to speed. Some of you will have experience with other vendors’ equipment, and some of you will not have much experience at all; therefore, we will focus on topics that will get your feet wet the quickest and have you talking Junos in no time.

When the hostname.domainname associated with my Small Office Home Office (SOHO) failed to update after a power outage, and a new DHCP-assigned external address was assigned to my router, I was reminded of the need for Dynamic DNS. This article will explore the implem...