Resource Library

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...

The technologies examined reduce operational expenses (OpEx), not capital expenses (CapEx) that has traditionally been the focus of virtualization. Many companies implemented virtualization with the goal of saving money in the form of fewer servers to buy with a side benefit of reducing the footprint of the servers and lowering the required power and cooling. Most of the savings were in capital, but do not expect the same with many of the technologies listed here, because some may even require some additional capital expenditures, at least for software, in order to save on the day-to-day operations of IT. The bigger cost in running an IT department is in the OpEx category anyway, so savings there are recurring.

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.

vSphere 5.5 is now available with myriad small improvements such as a faster Web Client, LACP, Autoscale and higher configuration maximums. In addition, there are changes coming such as VSAN, which may be ground-breaking in regard to VM storage of the future. Since the release of vSphere 5.5, they have not yet announced a change to the blueprint for the test. That being the case, I will say, for now, that the VCP-510 test should remain unchanged as well. My goal here is not to reeducate you on everything that you need to know for the test; instead, it is to point out the few changes that might apply in your company or organization.

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.

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.