Traditional Telephony Concepts

May 1, 2013 Joe Rinehart Cisco, Cloudera, Featured, Professional Development, Project Management, Routing & Switching, Technology, Training in Business

Cisco Voice Technologies, now typically referred to as Unified Communications Technologies, not only depend on a solid network foundation, but also use conceptual building blocks from the world of traditional telephony. The reasons for this are:

Capability to interconnect the Unified Communications Environment to the PSTN
Creating “new world” equivalent logical functions that mimic “old world” methodologies
Understanding the basic elements utilized in older telephony can help in knowing how these same functions are created in Unified Communications networks. Here we will map out the basics of an analog telephone call.

Getting Started with Cisco UC Technologies

April 23, 2013 Joe Rinehart Cisco, Cloudera, Featured, Professional Development, Project Management, Routing & Switching, Technology, Training in Business

When Alexander Graham Bell invented the first telephone in March 1876, he could hardly have conceived the impact it would have. Today, nearly a century and a half later, human beings communicate verbally using landline phones (e.g., traditional home telephone) and cellular telephones, and access data along these very same lines. Bell’s original device made use of analog technologies of the day, which was transitioned to digital transmission in the Public Switched Telephone Network (PSTN) core. Voice conversations in this proverbial world took place through a series of physical electrical circuits, thus named circuit-switched. The next progression and/or transition of telephony came in the form of packet-switched telephony, giving way to the all too familiar term VoIP (Voice over Internet Protocol). In positioning its technologies for this next-generation methodology, Cisco pioneered a number of critical elements that paved the way for practical, affordable telephony that we will examine here.

How To Troubleshoot Cisco Switches

March 21, 2013 Joe Rinehart Cisco, Cloudera, Featured, Professional Development, Project Management, Routing & Switching, Technology, Training in Business

For almost every network engineer, the “rite of passage” is a network outage or problem that was unpleasantly memorable and particularly difficult, and told in stories for years to come. The important concept here is to realize that while these things can and do happen, they should remain infrequent events rather than frequent occurrences. This is essentially what network troubleshooting and problem resolution is all about.

Dynamic Trunking Protocol Mechanics

February 19, 2013 Joe Rinehart Cisco, Cloudera, Featured, Professional Development, Project Management, Routing & Switching, Technology, Training in Business

As we mentioned previously, DTP was preceded by DISL, which created the structure and basic protocol operations in use today. Originally this required explicit configuration to enable the feature, but runs as the default on Cisco switch Ethernet interfaces today. Basic operation of DTP is as follows:

Dynamic Trunking Protocol

February 12, 2013 Joe Rinehart Cisco, Cloudera, Featured, Professional Development, Project Management, Routing & Switching, Technology, Training in Business

Most network professionals have a high degree of awareness of the principles of Virtual Local Area Networks (VLANs) and the importance of trunk links use to carry this data between switches. The underlying theory involved is at the foundation of most certification courses, various Cisco Press books, and even in breakout sessions at many conferences. While the proverbial “big picture” of the process is straightforward enough to the initiated, some of the nuances can become somewhat vague. Dynamic Trunking Protocol (DTP) and its predecessor, Dynamic Interswitch Link (DISL), are used to automatically negotiate the establishment of a trunk, but the many options and settings can become more confusing than helpful.