Resource Library

Cisco Unified Communication H.323 and SIP gateways will require a dial plan on those gateways to extend calls to endpoints that may be configured. An endpoint may be either an analog or digital voice port that would provide connections to the public switch telephone...

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...

Cisco IP phones support a variety of different audio codecs. In this post, I will explain some of the differences and explain which versions of CUCM and the Cisco IP phones support the various audio codecs. Audio codecs are responsible for sampling human speech (a s...

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...

In the previous discussion on QoS the Per-Hop Behaviors DiffServ uses to mark packets were identified. These where listed as:Expedited Forwarding (EF) – RFC 3246 – Provides a strict priority serviceAssured Forwarding (AF) – RFC 2597 – Provides a qualified delivery gu...

No matter what book or manual you use to study for the CCNA examination, you will see various protocols and processes referencing an RFC. And, although frequently referenced, the RFCs are seldom actually included in the documentation. So, the logical question becomes...

Cisco Unified Communications Manager (CUCM) includes a feature called "call throttling" that denies new call attempts when the system is in a state that may lead to delayed dial tone. The Real Time Monitoring Tool (RTMT) will generate a code yellow alert when call t...

When sending data end-to-end through a network, routers are used in internetworking to create a virtual network from one device to another, either locally or globally. Routers are configured to operate with most common network protocols. That means they know the form...

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.

Call Admission Control (CAC) is often times included as part of the same topic as Quality of Service (QoS), when in actuality CAC is a separate and complete topic itself. QoS is defined as traffic engineering on a packet switched network. This definition means movin...