二层组播QoS最优生成树

具有一对多特性的组播数据大量涌入以太网,对网络服务质量提出了更高的要求.二层域中生成树协议在选择根桥时没有考虑其对组播服务质量的影响.从二层组播接收者的角度出发,提出了二层组播QoS最优生成树的概念,从理论上证明了组播源位于最优生成树的根桥上时,组播能达到最优的服务质量.而且,最优生成树对于经过根桥的单播也能达到最优的服务质量.最后,给出的最优根桥逼近查找算法可以作为生成树算法的补充.通过对比实验,验证了该算法的有效性、可靠性和可扩展性.

QoS Optimized Spanning Tree for Layer 2 Multicast Applications

Recently, more and more QoS-sensitive multicast traffic comes into Ethernet, which requires higher quality of service (QoS) than traditional data traffic. As a result, the current spanning tree protocol (STP) can not provide satisfactory QoS for the new type traffic, because multicast traffic has inherent P2MP characteristic where the root bridge of STP is located greatly affecting its QoS in layer 2. However, the current STP just selects the bridge that owns the smallest bridge ID as its root bridge, leaving QoS out of consideration. In this paper, from the point of view of multicast receivers, the L2 multicast QoS optimized spanning tree concept is brought forward and it is proved that if multicast source is mobile, when multicast source is located at the root bridge of optimized spanning tree, multicast traffic gains optimized QoS. Otherwise, the bridge that multicast source is located at is selected as the root bridge of STP in order to get best multicast QoS. In addition, it is shown that unicast traffic, which shuttles through the root bridge of optimized spanning tree, gains optimized QoS too. Finally, an approximating lookup algorithm of the optimized root bridge is proposed as the complement of the spanning tree algorithm and the validity and reliability of this algorithm are verified in the experiment.