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ATM (Asynchronous Transfer Mode Networks)
This report aims to discuss Asynchronous Transfer Mode, known simply as ATM technology, as it pertains to Networking in a detailed and coherent manner. "It is clear that Asynchronous Transfer Mode (ATM) technology will play a central role in the evolution of current workgroup, campus and enterprise networks. "The ATM protocol is flexible enough to be used not only for local and wide area network applications, but also possibly for backplane processor-to-processor interconnection. The adoption of ATM for LAN applications has altered the industry landscape and significantly speeded up the expected deployment of ATM services by WAN service providers." (Estes, 1993) ATM delivers important advantages over existing LAN and WAN technologies, including the promise of scalable bandwidths at unprecedented price and performance points and Quality of Service guarantees, which facilitate new classes of applications such as multimedia." (Alles, 1995) The objective of this work therefore is to give the details of research on the topic and thus provide specific technical insights on the Asynchronous Transfer Mode layers. These layers include the ATM Layer, AAL Convergence sub-layer, ATM Adaptation Layer or AAL, the AAL Model Segmentation and Reassembly sub-layer and the Higher Layer Protocols for control, management, and application. As noted, the work intends to focus in on the technical aspects such as networking functions, communication between layers, and the components of the Asynchronous Transfer Mode Networks technology. This objective entails that only technical information on ATM's is presented and also entails that no definitions of what ATM's are or comparisons to other architectures are presented. In addition, another area avoided was the advantages and disadvantages of ATM's.
The ATM technology is a very detail oriented and maybe the most complex technology ever created in our current technologically driven society. "While the structure of ATM cells and cell switching do facilitate the development of hardware intensive, high performance ATM switches, the deployment of ATM networks requires the overlay of a highly complex, software intensive, protocol infrastructure. This infrastructure is required to both allow individual ATM switches to be linked into a network, and for such networks to internetwork with...
The first layer is the physical layer which defines the interface with transmission medias similar to the OSI reference model. Basically, the physical layer handles transmission rates by interfacing and detailing how ATM cells are converted into line signals. ATM cells are carried on SONET or synchronous digital hierarchy (SDH), T3/E3, TI/E1, or 9500 bps modems. It is important to note that ATM communication is independent of the physical transport so that separates it from other LAN technologies such as Ethernet protocols that specify a certain transmission medium. "The SONET technology that is used by telephone companies is considered as inadequate by data service providers. Data service providers should recognize that SONET remains the best system for providing ATM services." (Martin, 1995)
The next ATM layer handles ATM Cells which have a simple format of a 5 byte header and a 48-byte payload. Cell format headers hold key addressing information such as the ATM Cell Address as well as other vital information. The payload of the cell houses user data that will be transported over the network. Cells are forwarded serially and also propagated in a strict numeric sequence which helps to distinguish them throughout a network. When originated, payload length was created as a compromise between a long cell length of 64 bytes which would have most likely been more efficient if and when long frames of data had to be transmitted as compared to a short cell length of 32 bytes which would have minimized end-to-end processing delays and most likely would have been better for voice, video, and other delay-sensitive protocols. At 48 bytes, the cell payload length can easily accommodate two 24-byte IBP FastPackets.
To go into more detail for ATM cell formats, there are two main types of ATM cell headers: the user-network interface or UNI, and the network-to network interface or NNI. The user-network interface is an ATM specific or native-mode service interface for Wide Area Network or WAN technology. "Currently, many public network service providers are considering the deployment of public ATM networks, which will offer…
(Alles, 1995)
The AAL is made up of two sub-layers which complete the four layers of the Asynchronous Transfer Mode. The convergence sub-layer of CS and the segmentation and reassembly sub-layer or SAR. The convergence sub-layer receives data from applications and creates variable length data packets called convergence sub-layer protocol data units or CS-PDU's. The segmentation and reassembly sub-layer gets the CS-PDU's and maps them into the 48 byte payload of an ATM cell. There is also a variable bit rate called the AAL2. It is the connection oriented service that utilizes a synchronous protocol for timing transfers for compressed voice or video formats. A third approach is for handling variable bit rates with the AAL 3/4 process. This is used for connectionless services which never need timing transfers and are considered asynchronous. Examples of these are SMDS and LANs.
ATM switches provide the switching and multiplexing of cells in the system. "The fact that ATM is connection oriented implies the need for ATM specific signaling protocols and addressing structures, as well as protocols to route ATM connection requests across the ATM network. These ATM protocols, in turn, influence the manner in which existing higher layer protocols can operate over ATM networks." (Alles, 1995) Switches are designed to provide virtual paths as well as virtual channel switching
The company should use the Cisco hedge router to make the company to achieve a reliable communication over the internet. The edge router will also make the company to achieve higher capacity, scalability, and improve routing protocol convergence at lower costs. As traffic volume increases, the solution will allow the company to implement incremental bandwidth upgrades without necessarily changing the router interface. The edge firewall will be used to
MLPS QOS vs. ATM QOS Quality of Service (QOS) is best defined as the performance attributes of an end-to-end flow of data (Zheng, 2001). The particular elements of QOS depend on the information that is being transported. For example, QOS for voice defines limits on specific parameters such as delay, delay variation, packet loss, and availability. In the past, networks were engineered based on providing fixed bandwidth for relatively short duration voice
Telecommunications Act of 1996 was a high point in the history of telecommunications in the United States. It was coming twelve years after the breakup of AT&T; the Act endeavored to reposition all telecommunications markets in the direction of opposition. The Act imagined antagonism in all telecommunications markets, both in the markets for the numerous elements that included the telecommunications network, along with the final services the network generated.
technologies that are readily available for in-home internet access. You should consider practical as well as technical differences in your comparison. Do not include Frame Relay or ATM as these are primarily larger scale business solutions. Higher-speed standards up to 300+ Mbps 802.11n uses (MIMO) technology and a wider radio frequency channel. It provides a mechanism called frame aggregation to decrease time between transmissions Channels operating at 40 MHz are another feature incorporated
Communications This age is often referred to as the information era: the last two decades have given birth to some of the most staggering advancements that the human race has ever been capable of -- advancements which have changed the way that we live, do business, stay healthy, fight disease and defend our nation. It's vital to have a comprehensive and concrete understanding of some of the more basic concepts
In other words, as coding begins, testing begins and continues as a parallel process to the coding activity. Even when the installation process has begun, testing should continue. Installation is the process of actually replacing the current system or programs with the new system or programs. Thus, coding, testing, and installation processes create several deliverables that can be used as signoff points for management. The testing and implementation process should