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时下最时髦的话题之一就是“上网”。而网上的各种应用,特别是高分辨率图像的传输、视频会议、VOD等多媒体应用的增长,使网络迅速饱和,并显得拥挤不堪,网络成为限制应用增长的瓶颈(Bottleneck)。在传统的共享式的网络中,如10M Ethernet,所有站点共享10Mbps的带宽。如果有n台计算机,平均下来,每台所分得的带宽是10M/nbps。随着站点数的增加,而共享的带宽不变,使网络的效率越来越低。应用对带宽的需求导致网络从共享走向交换。将交换技术引入局域网,就可建立一个地理位置分散的网络,局域网交换机的每一个端口可并行地、同时地、安全地互相传输数据;而且交换式局域网又是高度可扩展的,其带宽随着用户站点数的增加而增加。 在交换式网络结构中,虚拟局域网 (VLANVirtual LAN)则充当着“灵魂”的身份。交换的诱人之处便在于构成VLAN。任何技术都有促使其产生的土壤,有适合其发展的空间,VLAN也不例外。
One of the most fashionable topics nowadays is “Internet.” With the growth of various online applications, especially high-resolution image transmission, video conferencing and VOD applications, the network quickly becomes saturated and becomes overcrowded. As a result, the Internet has become the bottleneck that limits the growth of applications. In traditional shared networks, such as 10M Ethernet, all sites share 10Mbps of bandwidth. If there are n computers, on average, the bandwidth each gets is 10M / nbps. With the increase in the number of sites, while the shared bandwidth unchanged, the network efficiency is getting lower and lower. The application’s demand for bandwidth has led to the shift of networks from sharing to switching. The exchange of technology into the LAN, you can establish a geographically dispersed network, LAN switch each port can be parallel, simultaneous and secure data transfer to each other; and switched LAN is highly scalable, with its bandwidth as The number of user sites increases. In switched network architectures, VLANs (virtual LANs) act as “souls.” The attractiveness of exchange lies in the formation of VLAN. Any technology has prompted its generation of soil, there is room for development, VLAN is no exception.