Resource Library

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.

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.

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).

This week we'll review the IPv4 Address Classes including subnet masks, examples of Class C, Class B, and Class A subnet masks, and planning IPv4 addresses.

Both technologies, Ethernet and FC, satisfied the two conditions at that time, but there was a catch. Read more.