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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. 

For smaller companies, configuring a dial plan to account for variations in dialed numbers is often not a problem. However, companies that are larger and more global in nature encounter a number of issues when designing their dial plan approach.

Border Gateway Protocol (BGP) is a fascinating protocol because there are a lot of things that can be done with BGP. However, there has always been an issue with BGP, which is convergence (the time the network or protocol takes to accept change). BGP was designed for scale, not speed, so it’s something that we’ve had to tolerate from its inception.

License provisioning has always been a bit of a challenge in the CUCM environment. Prior to CUCM v9.0, licensing was managed on a per-cluster basis with each cluster requiring its own license files that were tied to the media access control (MAC) address of the cluster’s publisher. This approach to license management was limiting in the fact that one cluster might have unused licenses while another cluster may be at its limit and sharing between clusters was not possible.

Occasionally I am asked to configure the ability to block calls based on Caller ID. Prior to Cisco Unified Communications Manager (CUCM) v8, the only way to block these calls was to configure voice translation rules and profiles on the gateway receiving the calls. This has changed in CUCM v8 with the introduction of an additional parameter in translation patterns: Route Next Hop By Calling Party Number.

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.

While most organizations have not yet fully (or in many cases even partially) adopted cloud computing, the trend is growing in all but the smallest businesses.

The process of learning how to subnet IP addresses begins with understanding binary numbers and decimal conversions along with the basic structure of IPv4 addresses. This paper focuses on the mathematics of binary numbering and IP address structure.

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.

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.

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.

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.

In the spring of 2013, Cisco announced major updates to their Cisco Certified Network Associate (CCNA) curricula, including a new version of the CCNA Routing and Switching exam (200-120 CCNA). This paper provides a review of the CCNA Routing and Switching exam's critical concepts, as an aid to students preparing to pass the latest version of the CCNA Routing and Switching exam.

Many companies are already using VoIP while incorporating video capabilities into their portfolio of services. One question that I am often asked is, “How can we ensure that the voice and video quality is good and consistent when using VoIP?”

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.

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?

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 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.

Instructor Carol Kavalla talks about the advantages of taking a Cisco Data Center Unified Fabric Implementation class from Global Knowledge.

In this report, I've reviewed the 15 most popular certifications according to our more than 12,000 North American respondents to our annual IT Skills and Salary Survey. For each certification, you'll find a brief description, the average salary, and some insight into why it is popular.

You know you need to invest in training, but how do you get the best return on investment (ROI) from your training dollars? To help you make smart training decisions, we've put together this guide, which illustrates some alternative and little-known payment options, the types of discounts and promotions available with training and a suggested list of courses that give you excellent value.

Need to control the digits contained in the telephone number that enter or leave a gateway? Digit manipulation involves adding, subtracting, and changing telephone numbers. You can manipulate calling numbers, called numbers, and redirecting numbers, as well as the numbering plan and ISDN number type. Learn about the techniques that are applied to incoming or outgoing calls, or globally to all calls. You can also manipulate telephone numbers before or after a dial peer is matched.

Frequently, questions come up in the Cisco Contact Center Express classes I teach concerning the ability of the system to perform this or that task. In this blog post, I will cover some of the more popular questions I get during class.

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

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

In numerous Cisco classes, students learn about IPv4 and IPv6 address subnetting, complex subnetting, variable length subnet masking (VLSM), summarization, prefix routing, and address aggregation. These are valuable skills. In order to apply these skills efficiently, a network designer should possess one additional skill. Planning the IP address space for a Class A or B IPv4 address is necessary to apply the complex skills listed above properly. Complex subnetting, VLSM, and IP address summarization can be implemented simply and efficiently with proper planning.

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.

Meet Global Knowledge course director and lab topology architect Joey DeWiele, a specialist in Unified Communications. Joey will walk you through the benefits of our exclusive Cisco UC lab architecture - a more scalable and stable approach to the all-important labs featured in unified communications courses. Our labs feature upgraded hardware and software including Custom Lenovo T61 PCs, 7965 IP Phones, 3560 Switches and Call Manager 7. With our flexible UC architecture, students are able to view and experience the full lab architecture regardless of which Cisco UC course they are taking or the skill set they are seeking. The lab architecture features a realistic network with redundant environments that are made rich with multiple machines, pre-deployed tools with shortcuts, online documentation that is particular to individual pods, and multiple OS support for all virtual machines (Windows, Linux, VMware).

Global Knowledge instructor Doug Notini discusses the benefits of our FIREWALL 2.0 - Deploying Cisco ASA Firewall Solutions course.

Diane Teare, Global Knowledge's Cisco Course Director, discusses the advantages to taking our CCNA Boot Camp.

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

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.

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

Course director Jim Thomas explains how our custom labs, which utilize external hosts, ISR routers, and DMZ, provide a real-world environment for students.

Rodger Foster, our senior Cisco instructor, reviews how multiple gateways are used to provide redundancy in the network.

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.

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.

As we discussed previously, Cisco created the Nexus Operating System (NX-OS) to power its next-generation data-center switching platform. While this new OS shares many similarities to the original IOS, there are some definite differences that you need to be aware of as you begin using it.

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).