In tranditional ip network , only the “ best effort ” service is provided , but the quality of service can not be guaranteed . though the interserv , deffserv and mpls are presented afterward to guarantee the qos for the ip network . but as a layer network , the realization of the qos function need span different layers ( such as rsvp protocol ) in the ip network , which may result in the function iterance and chaos 多媒體和實時業(yè)務(wù)的出現(xiàn)要求網(wǎng)絡(luò)能夠提供足夠的qos保證,在傳統(tǒng)的ip網(wǎng)絡(luò)中只能提供“盡量傳輸”的服務(wù)而不能保證服務(wù)質(zhì)量,后來提出的綜合服務(wù)模型( interserv )以及區(qū)分服務(wù)模型( deffserv )以及mpls技術(shù)保證了ip網(wǎng)絡(luò)上的服務(wù)質(zhì)量,但由于ip網(wǎng)絡(luò)是層次結(jié)構(gòu)的網(wǎng)絡(luò),因此對qos的支持需要跨層(如rsvp協(xié)議) ,這就可能引起功能的重復(fù)和混亂,而微通信元系統(tǒng)是無層次結(jié)構(gòu)的網(wǎng)絡(luò)系統(tǒng),就克服了這些的問題,變得簡單,效率更高。