Browsing by Author "Hsu, NB"

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Extension of RP relocation to PIM-SM multicast routing
(2001)
Lin, YD
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Hsu, NB
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Pan, CJ
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資訊工程學系
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Department of Computer Science
The Protocol Independent Multicast-Sparse Mode (PIM-SM) protocol establishes core-base tree to forward multicast datagrams in a network. In PIM-SM, the core or Rendezvous Point (RP) of a group is determined at each multicast router by hashing a group address, i.e., a class-D IP address, to one of the candidate RPs. The hash function is characterized by its ability to evenly and uniquely choose the core for a group and remains insensitive to the geographic distribution of the group members and the sources. However, it may result in a multicast tree with high cost. This study presents a relocation mechanism which is extension to PIM-SM, in which RP could be relocated periodically. When a new RP is found, the original RP informs all members to re-join to the new RP, Simulation results indicate that the extended version, RPIM-SM, reduces about 20% tree cost than PIM-SM when the group size is medium. Moreover, comparing RPIM-SM with the optimal core-based tree reveals that they have less than 5% difference in tree cost. Furthermore, an increase of the number of candidate RPs brings RPIM-SM even closer to the optimal core-based tree. Results in this study demonstrate that relocation improves the performance of PIM-SM.
Interoperability of EFCI and ER switches for ABR services in ATM networks
(1998-01-01)
Lai, YC
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Lin, YD
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Hsu, NB
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資訊工程學系
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Department of Computer Science
I Vith the advances in switching technologies, ER switches are becoming popular since they perform better than EFCI switches. In the transitional period, the EFCI and ER switches may coexist ill the same ATM network. Hence the efficiency of various ER schemes should be considered in the mixed EFCI-ER environment, not only in the homogeneous ER environment. In this paper we describe five ER control mechanisms and compare their performance in the mixed EFCI-ER environment. Simulation results show that these algorithms can interoperate with the EFCI switches. However, the behavior of these ER schemes in the mired EFCI-ER environment is sometimes different,vith that ill the homogeneous ER environment. These ER schemes are re-evaluated based on their interoperability with EFCI schemes.
QoS routing granularity in MPLS networks
(2002-06-01)
Lin, YD
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Hsu, NB
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Hwang, RH
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交大名義發表
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National Chiao Tung University
This study investigates how constraint-based routing decision granularity significantly affects the scalability and blocking performance of QoS routing in an MPLS network. Coarse granularity, such as per-destination, has lower storage and computational overheads but is only suitable for best effort traffic. On the other hand, fine granularity, such as per-flow, provides lower blocking probability for bandwidth requests, but requires a huge number of states and high computational cost. To achieve cost-effective scalability, this study proposes using hybrid granularity schemes. The overflowed cache of the per-pair/flow scheme adds a per-pair cache and a per-flow cache as the routing cache, and performs well in blocking probability. The per-pair/class scheme groups the flows into several paths using routing marks, thus allowing packets to be label-forwarded with a bounded cache.
RPIM-SM: extending PIM-SM for RP relocation
(2002-12-01)
Lin, YD
;
Hsu, NB
;
Hwang, RH
;
資訊工程學系
;
Department of Computer Science
The protocol independent multicast-sparse mode (PIM-SM) protocol establishes core-base tree to forward multicast datagrams in a network. In PIM-SM, the core or rendezvous point (RP) of a group is determined at each multicast router by hashing a group address, i.e. a class-D IP address, to one of the candidate RPs. The hash function is characterized by its ability to evenly and uniquely choose the core for a group and remains insensitive to the geographic distribution of the group members and the sources. However, it may result in a multicast tree with high cost. This study presents a relocation mechanism, which is extension to PIM-SM, in which RP could be relocated periodically. When a new RP is found, the original RP informs all members to re-join to the new RP. Simulation results indicate that the extended version, RPIM-SM, reduces about 20% tree cost than PIM-SIM when the group size is medium. Moreover, comparing RPIM-SM with the optimal core-based tree reveals that they have less than 5% difference in tree cost. Furthermore, an increase of the number of candidate RPs brings RPIM-SM even closer to the optimal core-based tree. Results in this study demonstrate that relocation improve the performance of PIM-SM. (C) 2002 Published by Elsevier Science B.V.
Service-sensitive Routing in DiffServ/MPLS networks
(2001-10-01)
Hsu, NB
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Lin, YD
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Li, MH
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Lee, TH
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資訊工程學系
This study investigates the problem of unfairness when QoS routing does not consider the in ix of traffic classes. Unfairness is mainly caused by routing different traffic flows of the same class through paths with extremely different traffic mixtures, involving various service classes. Next, a new routing scheme-Service-sensitive Routing (SSR), which takes the state of traffic mixture of the various service classes into account, is proposed. To determine the QoS route for a flow request, SSR not only considers the available bandwidth and delay of the candidate paths, but also considers the mix of traffic classes on the paths. Additionally, the hybrid granularity routing decision in SSR scheme is scalable and suitable for the Differentiated Services and MPLS networks. Extensive simulations show that SSR can effectively reduce the variance of the average of queuing delays, for example by approximately 20% to 35% for a moderate offered load, compared to the shortest path routing. Furthermore, this routing scheme reduces the fractional reward loss and bandwidth blocking probability.