أسلوب النقل اللاتزامني
أسلوب النقل التزامني ATM هو أحد بروتوكولات نقل البيانات من خلال تبديل الرزم (packet switching) والتحكم في المهلات (delay)، ويمكنه نقل كافة أنواع البيانات (الصوت والفيديو والبيانات) ويستخدم رزما ثابتة الحجم تعرف باسم (الخلايا cells)، وتتكون الخلية من 53 بايت تنقسم إلى قسمين: 5 بايتات لرأسيات الرزمة (Header) (التي هي بيانات عناوين المصدر (source) والمقصد (destination) وبيانات التحكم والتوقيت المطلوبة من أجل نقل البيانات بنجاح 48 بايت للحمولة النافعة (payload) التي هي البيانات المطلوب نقلها سواء كانت في صورة صوت أو فيديو أو مجرد بيانات.
Deployment
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ATM became popular with telephone companies and many computer makers in the 1990s. However, even by the end of the decade, the better price–performance ratio of Internet Protocol-based products was competing with ATM technology for integrating real-time and bursty network traffic.[1] Additionally, among cable companies using ATM there often would be discrete and competing management teams for telephony, video on demand, and broadcast and digital video reception, which adversely impacted efficiency.[2] Companies such as FORE Systems focused on ATM products, while other large vendors such as Cisco Systems provided ATM as an option.[3] After the burst of the dot-com bubble, some still predicted that "ATM is going to dominate".[4] However, in 2005 the ATM Forum, which had been the trade organization promoting the technology, merged with groups promoting other technologies, and eventually became the Broadband Forum.[5]
Wireless or mobile ATM
Wireless ATM,[6] or mobile ATM, consists of an ATM core network with a wireless access network. ATM cells are transmitted from base stations to mobile terminals. Mobility functions are performed at an ATM switch in the core network, known as a crossover switch,[7] which is similar to the mobile switching center of GSM networks.
The advantage of wireless ATM is its high bandwidth and high-speed handoffs done at layer 2. In the early 1990s, Bell Labs and NEC research labs worked actively in this field.[8] Andy Hopper from the University of Cambridge Computer Laboratory also worked in this area.[9] There was a wireless ATM forum formed to standardize the technology behind wireless ATM networks. The forum was supported by several telecommunication companies, including NEC, Fujitsu and AT&T. Mobile ATM aimed to provide high-speed multimedia communications technology, capable of delivering broadband mobile communications beyond that of GSM and WLANs.
انظر أيضاً
ملاحظات
References
- ^ Steve Steinberg (October 1996). "Netheads vs Bellheads". Wired. Vol. 4, no. 10. Retrieved 24 September 2011.
- ^ Baumgartner, Jeff (1 March 2000). "Land Rush Reaches the Headend". Multichannel News International. Cahners. p. 35. Retrieved 30 November 2024.
- ^ "What's in store for FORE?". Network World. 16 September 1996. p. 12. Retrieved 24 September 2011.
- ^ "Optical Ethernet firms brave stormy industry seas". Network World. 7 May 2001. p. 14. Retrieved 24 September 2011.
- ^ "About the Broadband Forum: Forum History". Archived from the original on 9 October 2011. Retrieved 24 September 2011.
- ^ "The Wireless ATM Debate". archive.ph. 15 June 2013.
- ^ Book on Wireless ATM Networks - Chai Keong Toh, Kluwer Academic Press 1997
- ^ WATMnet: a prototype wireless ATM system for multimedia personal communication, D. Raychaudhuri, et al.
- ^ "Cambridge Mobile ATM work". Archived from the original on 25 June 2015. Retrieved 10 June 2013.
Further reading
- Black, Uyless D. (1998). ATM—Volume III: Internetworking with ATM. Toronto: Prentice Hall. ISBN 0-13-784182-5.
- De Prycker, Martin (1993). Asynchronous Transfer Mode. Solutions for Broadband ISDN. Prentice Hall.
- Joel, Amos E. Jr. (1993). Asynchronous Transfer Mode. IEEE Press.
- Golway, Tom (1997). Planning and Managing ATM Network. New York: Manning. ISBN 978-0-13-262189-2.
- McDysan, David E.; Darren L. Spohn (1999). ATM Theory and Applications. Montreal: McGraw-Hill. ISBN 0-07-045346-2.
- Neelakanta, P. S. (2000). A Textbook on ATM Telecommunications, Principles and implementation. CRC Press. ISBN 0-8493-1805-X.
وصلات خارجية
- "ATM forum". Archived from the original on 1 July 2005.
- "ATM Info and resources". Archived from the original on 2 January 2013.
- ATM ChipWeb - Chip and NIC database
- "A tutorial from Juniper web site". Archived from the original on 2008-10-13.
- "ATM Tutorial". Archived from the original on 2007-01-14.
- "Asynchronous Transfer Mode Switching". DocuWiki. Cisco Systems. Archived from the original on 2018-01-31.
- "ATM Cell formats". Cisco Systems. Archived from the original on 2012-12-06.
- "Asynchronous Transfer Mode (ATM)". Cisco Systems. Archived from the original on 2007-10-29.