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The OSI model is a conceptual tool used to discuss and describe network functions. The use of a standard reference model is essential to communicate ideas as well as create new technologies. It is a good idea to be familiar with the OSI model, the features assigned to each layer, and examples of common protocols or technologies associated with the OSI layers.
Diane Teare, Global Knowledge's Cisco Course Director, discusses the advantages to taking our CCNA Boot Camp.
As mentioned earlier, one of the most useful pieces of guidance that ITIL provides relates to the categorization of suppliers. ITIL describes four categories of suppliers:
Enterprises, whether they are commercial, non-profit, or government entities, are operational organizations that operate through the execution of hundreds of processes. The quality of these processes affects every aspect of the enterprise and these processes are rarely static. Business Process Analysis (BPA) is the discipline of examining processes so that they may be changed to align with enterprise objectives.
One of the many useful features of tunneling is to carry non-IP traffic across an IP network, and this is still the case when dealing with IPv6 traffic. This transition mechanism makes use of a configured tunnel to transport IPv6 over a native IPv4 network, which may consist of two sites or more. Unlike the previous transition mechanisms, tunneling is not monolithic; while the basic principles may be similar, the operations are different. The following chart gives a breakdown of the current, major tunneling types in use, particularly in a Cisco environment:
As with the adoption of any new technology, the move from IP version 4 to IP version 6 will take a number of years to complete. During that transition phase, various mechanisms will be necessary to continue support of the older protocol as the newer gains widespread momentum. In addition, there has been some evolution even within the availability of these mechanisms, some of which have already passed from general use into deprecated status. Network engineering professionals already proficient in the use of IPv6, as well as the available coexistence mechanisms, will undoubtedly stay in high demand throughout this process.
The STP (Spanning Tree Protocol) standard (IEEE 802.1d) was designed when the recovery after an outage could wait a minute or so and be acceptable performance. With Layer 3 switching in LANs, switching began to compete with routers running protocols because they are able to offer faster alternate paths. Rapid Spanning Tree Protocol (RSTP or IEEE 802.1w) brought the ability to take the twenty seconds of waiting for the Max Age counter plus fifteen seconds of Listening plus fifteen seconds of Learning or fifty seconds down to less than one second for point-to-point connected and edge switches and six seconds for root switches.
In a recent post, I gave an overall description of a service portfolio and the key components of a portfolio. Here, I will describe how a cloud services provider might implement an ITIL service portfolio. A cloud services provider will regularly have a set of services under development, a set of service in live operation, and a set of services that are retired.
ITIL describes a service portfolio as a collection of the overall set of services managed by a service provider. A service portfolio describes a service provider’s boundaries and promises across all of the customers and market spaces it serves. I like to think of a service portfolio as describing the past, present, and future collection of services offered by a service provider. The figure below shows a high-level view of a service portfolio.
This short example illustrates basic VLAN operation. Examining VLANs in a large-scale installation can show the full benefits of VLANs. Consider that this is a small portion of a large corporate headquarters with 5,000 devices connected in a 20 building campus.