标签: cisco

        如上图所示，CISCO 有自己的 3 层层次模型  1 ， 接入层  2 ，汇聚层  3 ，核心层。 ?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /   接入层： 接入层通常指网络中直接面向用户连接或访问的部分。接入层目的是允许终端用户连接到网络，因此 接入层交换机 具有低成本和高 端口密度 特性。接入 交换机 是最常见的 交换机 ，它直接与外网联系，使用最广泛，尤其是在一般办公室、小型机房和业务受理较为集中的业务部门、多媒体制作中心、网站管理中心等部门。在传输速度上，现代接入 交换机 大都提供多个具有 10M/100M/1000M 自适应能力的端口。 在 核心层 和 汇聚层 的设计中主要考虑的是网络性能和功能性要高，那么我们在接入层设计上主张使用性能价格比高的设备。接入层是最终用户 ( 教师、学生 )  与网络的接口，它应该提供即插即用的特性，同时应该非常易于使用和维护。当然我们也应该考虑 端口密度 的问题。 接入层由 无线网卡 、 AP 和 L2Switch 组成，按照 宽带网络 的定义，接入层的主要功能是完成用户流量的接入和隔离。对于 无线局域网 WLAN 用户，用户 终端 通过 无线网卡 和 无线接入点 AP 完成用户接入。 接入层交换机： 接入层交换机 一般用于直接连接电脑，具有低成本和高端口密度特性。 接入层交换机 端口的 input  指服务器向交换机端口发送的数据，即是服务器发送出去的数据。 接入层交换机 端口的 output  指交换机端口向服务器传输的数据，即是服务器收到的数据。  

Collaboration technologies as a whole, encompassing emerging voice, video, social and other platforms, have played a transformational role in the way humans live, work and play over the past 10 years. Lynda Graton's testimonial book, "The Shift: Future of Work," plays out the future in a globalised, technology-centric and carbon-efficient economy. With rapid growth in the cloud-based consumption of IT services, the next few years starting with 2013 will witness a tipping point owing to the confluence of consumer and enterprise social platforms, ubiquitous video (the "New Voice") enablement, and, exponential growth in smart mobile/personal devices accessing the Internet. Emerging web-based enterprise social platforms with fully integrated, enterprise quality video, coupled with high-end video analytics, and, video/voice/text content management + search capabilities will disrupt traditional applications centred primarily on email and text-based documents for business collaboration. Delivery of this experience via mobile/personal devices (BYOD) from the cloud (private, public, hybrid) will fulfil the anytime-anywhere business collaboration experience. A similar pattern can be expected in the consumer social platform space once cost structures for large volume, self-service deployments are optimised. In parallel with human-to-human collaboration, an exponentially increasing trend for machine-to-machine collaboration via autonomic networks will provide a rich fabric of basic and value-added collaboration services. Auto-discovery of device and service touch-points together with rapid adoption of IPv6 will facilitate the growth of on-demand, ad-hoc collaboration between individuals and/or communities via self-organized network overlays. Apart from companies like Cisco, there is a lot of active research in academia to realise the deployment of such technologies. In summary, collaboration technologies will increasingly accelerate the emergence of a truly globally connected society and workforce. - Narayanan Subramaniam, Principal Engineer, Voice, Video Collaboration Technologies, Cisco Systems

The demise of the Flip video camera reads like the opening of a great murder mysteryor at least a decent Law and Order episode. Someone (or in this case, something) has been killed, there are a few suspects, but very few clues. Or, more accurately, we know who done it: Cisco Systems Inc., the Silicon Valley networking gear giant that set its sights on the consumer video market and forked over $590 million to acquire Pure Digital Inc., the inventor of the Flip, in 2009. What we don't have, and what very few people appear to have even sound theories on, is motive. Clearly, Cisco wanted out of a consumer business that it never really understood and that offered pitiful margins compared with Cisco's big ticket networking gear. (As evidence, several analysts cite the flop of Cisco's Umi video conferencing devices, which carried a price tag$600 plus $25 per month for servicethat many felt was untenable.) But the company's decision to pull the plug on the Flip businessrather than sell it offhas many people scratching their heads. The Flip, which first hit the market under that name in 2007, is currently the No. 1 selling camcorder on Amazon.comthe black Flip UltraHD, that is. A total of four Flip models are among the top 10 selling camcorders on Amazon. According to the New York Times, a total of 7 million Flip camcorders have been sold to date and Cisco itself claimed that Flip represented 35 percent of the camcorder market. "At the end of the day, they were selling quite a few of these things," said Michael Gartenberg, an analyst at market research firm Gartner Inc. But despite this impressive positioning, it's pretty clear that nobody would have paid Cisco anywhere near $590 million to acquire the Flip businessand here is where our chief suspect, smartphone convergence, comes in. The market for camcorders, especially small, mobile camcorders like the Flip, is on the wane. In fact, according to market research firm IHS iSuppli, overall camcorder shipments have been relatively stagnant since at least 2003the firm projects that in 2012 about 17.2 million camcorders will ship worldwide, compared to about 17.3 million in 2003. Analysts have long warned that gadgets that specialize in one thing would be threatened by the convergence of devices that can do several things. Smartphones are the biggest thug, growing enormously in popularity andin a competition for marketshare among each otherrapidly adding new functionality. The fact of the matter is that nearly everyone who packs a smartphone todayand even more so a year or two from nowis already lugging around a pocket-sized device that shoots video of comparable or better quality than the Flip. Even so, someone would have paid something for the Flip business, which would have included a market-leading product, a lauded brand and a creative team of designers who shocked the world once and, who knows, could do it again. What accountants have to say Sources said Cisco had signaled its desire to exit the consumer market and was advised to seek a buyer for the Flip business. It is not known if Cisco engaged in discussions with any other company about a possible sale. A spokesperson for Cisco did not immediately respond to a request for an interview. "Sometimes it comes down to what the accountants have to say," Gartenberg said. According to Gartenberg, it seems likely that Cisco calculated that it would be easier and ultimately less costly to simply shutter the unit and write it off, rather than going to the time and trouble of finding a buyer and selling Flip at a considerable loss. "Someone at Cisco ran the numbers and decided that this was the way to go," Gartenberg said. New York Times columnist David Pogue last week theorized that the most plausible reason Cisco choose to kill the Flip business rather than sell it is because Cisco wants to hold onto the Flip technology , presumably to apply to other areas. But it's not clear what about the Flip technology would be applicable to Cisco's other businesses, though the company said in its statement last week that video remains one of its five key company priorities. (Pogue also reported that Cisco was supposed to release a new Flip model last week, FlipLive, capable of live video broadcasting to the Internet). Jordan Selburn, a consumer electronics analyst at market research firm IHS iSuppli, said that despite Flip's position in the marketplace, the Flip unit may have simply been unprofitable. "Cisco may have simply decided that they don't have consumer DNA," Selburn said. "Part of the problem with Flip was once you bought one, you never had a reason to buy another one," Gartenberg said, adding that Cisco "lacked an understanding of the marketplace." "This is a sad thing for the whole industry," said Rick Doherty, co-founder and director at the Envisioneering Group. Doherty said the Flip design team made a serious impact on the consumer electronics world and predicted that its members would resurface and "spread their wings." "Camcorders are still a good business for many people," Doherty said. "There will be more innovation there, and great things will probably be coming. It's just a shame that Cisco took this route of not heeding industry trends and not, it seems, even respecting the company that they acquired." So it would seem that we can't make a case against convergence alone in the killing of the Flip. But clearly its fingerprints were among those found at the scene of the crime. According to Selburn, the "dedicated single-tasker"a gadget with only one applicationis under fire in all areas of consumer electronics, thanks in large part to the threat posed by multiple-application devices like the smartphone and media tablet. "That doesn't mean that they are all going away or doing badly," Sulburn said. Let's take a look at some of the other heretofore populareven belovedconsumer electronics devices that face threat from this menace at large. MP3 player/iPod Yep. Even the Babe Ruth of consumer electronics gadgets (they both changed forever their respective games) faces pressure from the convergence of applications in smartphones, most specifically by its dastardly younger brother, the iPhone. Apple reported selling 19.45 million iPods in the first quarter of this yearbrisk business to be sure, but the lowest first quarter total for the iPod since 2006. Okay, so the iPod isn't going to disappear in the next few years or, probably, in the next few decades. But there is a clear trend line. According to Gartner's Gartenburg, standalone, single-application devices such as music players can continue to command a significant marketalbeit a declining oneas long as over time they get less expensive and continue to evolve. "If business wasn't a good business, Apple would be out of it," Gartenburg said. "They are still very much in it, refreshing that product every year, even though they have other products like the iPhone that function as a music player." According to IHS, after peaking at more than 197 million units in 2007, the market for all digital music players is projected to decline from 180.1 million units in 2010 to 160.6 million units next year. "The market isn't going away," Selburn said. "But for a market that was pushing 200 million units a few years ago, we are looking at about a 40 percent decline between 2008 and 2016." Selburn says the biggest remaining advantage for single-taskers overall, and perhaps for the music player in particular, is that the apps-packed smartphones and media tablets also carry monthly data fees. For a 10- or 11-year-old kidor anyone for that matterwho just wants to listen to some music but doesn't care to check email, tweet or update his/her facebook status, the iPod and its like are still the way to go, Selburn pointed out. Digital music players "won't go away unless the data plan costs go away," Selburn said. "And that seems to be headed in the other direction." Interestingly, though sales of the iPod and other music players are in decline, there has been a shift in sales toward higher-end music players, rather than the low-end, according to Selburn.