Improved VC-merging method in MPLS networks

VC-merging allows VCs to be mapped onto the same VC label. In MultiProtocol Label Switching (MPLS) domain, ATM-LSR needs VC-merging method because of network scalability problem. VC-merging also plays an important role in providing multipoint-to-multipoint multicast and share-tree multicasting paradigm. When VC-merging is applied to multiple streams of Incoming packets, all the VC-merged cells have same label at the output port of ingress node. If those VC-merged cells are transmitted using AAL5, cell interleaving occurs. Thus, at the egress node of VC-merging an identification process is required in order to distinguish cells belonging to a packet from other cells. Various approaches have been proposed to help this identification process. In this paper, we propose improvements to the traditional VC-merging technique to minimize the need for additional buffers at intermediate merge points; to decrease end-to-end delay. This improved VC-merging mechanism requires receiving nodes to have a corresponding queue for each queue of sender node, such that cells from a particular queue of sender node is queued in a corresponding queue of the receiving node. In order to distinguish VC-merged cells from non VC-merged cells, an Information Cell is used. Upon arrival of a cell at sender node, the scheduler of sender node transmits the cell immediately based on Round-Robin algorithm. Simple equations In this paper show that the improved VC-merging method has advantages against the traditional methods In terms of buffer size and end-to-end delay time. Furthermore, if we change the scheme of queue searching(e.g. WFQ), QoS can also be supported.