多重協定標籤交換 (Multi-protocol label switching , MPLS)是近年來在網際網路上發展相當快速的一項技術。此技術的目標旨在能增加現有網際網路上封包交換的速度，使得網路大小及容量易於擴充，並可提供不同的服務等級(Class of Service)能力等。行動通訊 (mobility)在未來的通訊網路的設計上，已是一個很重要的趨勢。所以未來在MPLS的架構上，也可能會利用其優點來支援行動通訊的服務。
行動式網際網路協定 (mobile IP)，主要是使用在非連接導向特性的網際網路環境上支援行動通訊。而另一方面，MPLS主要是在連接導向的環境下操作。所以為了要支援行動通訊，一個以MPLS為基礎的網路必須先解決遞交後重新路由 (handoff rerouting)的問題。在此論文中，我們研究MPLS與行動通訊之技術，以其在一MPLS的主幹網路上提供有效率的行動通訊服務。本論文主要著重於在支援行動通訊的MPLS網路上，設計出三種解決遞交後重新路由的方法，並比較其個別效能。此三個方法包括全部路徑重建之遞交後重新路由 (all rebuilt rerouting scheme)、延伸原有路徑之遞交後重新路由 (extended rerouting)、以及標籤交換路徑之遞交後重新路由 (LSP rerouting)。某一些MPLS的特殊功能，像是標籤交換路徑之資源保留、迴路移除等，也被考慮用以改善此三種遞交後重新路由方法的效能。本論文之模擬，主要是要求得遞交後重新路由之延遲 (rerouting latency) 以及端點對端點之延遲 (end-to-end delay)兩個參數，並藉由此兩個參數的值，可以得到各個遞交後重新路由之方法在MPLS網路上的特性並比較其效能。而結果顯示，標籤交換路徑之遞交後重新路由其效能在這些遞交後重新路由的方法中是較突出的。

Multi-Protocol Label Switching (MPLS) is a new technique which is expected to provide a higher bandwidth capacity with QoS-guaranteed services and a faster packet forwarding mechanism than the traditional store-and-forward routing mechanism that is still being used currently over data networks. Mobility is becoming an attractive feature in modern communication network design. It is promising to use the MPLS framework, the span or partiality of the routing path, to support mobile services in the future.
Mobile IP is operated in connectionless mode and is currently used in the Internet to support mobility. On the other hand, MPLS is expected to work with Internet in connection-oriented mode. To support mobility, an MPLS based Internet has to deal with the handoff rerouting problem. In this thesis, we study MPLS as well as the mobility in order to provide efficient host mobility for the wired backbone network with MPLS capability. The main focus of this thesis is the design and comparison of the three handoff rerouting schemes, the all rebuilt rerouting scheme, the extended rerouting scheme, and the LSP rerouting scheme for the support of host mobility over MPLS networks. Special functions such as LSP reservation and loop removal are also considered to further improve the three rerouting schemes. Simulations were performed to compare the rerouting latency and end-to-end delay among these rerouting schemes. We can observe the characteristics of these rerouting schemes implemented in the MPLS network from simulation results. The results show that the performance of the LSP rerouting scheme outperforms among the proposed schemes.

Chapter 1 Introduction1
1.1 Layer 3 Switching Forwarding Technology2
1.2 Mobility3
1.3 Motivation4
1.4 Goals of This Thesis4
Chapter 2 Multi-Protocol Label Switching6
2.1 Motivation of MPLS6
2.2 Terminologies of MPLS8
2.3 MPLS basic operation10
2.3.1 Forwarding Plane10
2.3.2 Control Plane14
2.3.3 LSP Building in Control Plane17
2.4 Label Format22
2.5 Route Selections23
2.6 Multi-protocol and Hierarchical Operation23
Chapter 3 The Study of Mobility and Rerouting Schemes28
3.1 The Architecture of Mobility28
3.2 Rerouting Schemes in Mobile IP29
3.3 Rerouting Schemes in Wireless ATM31
Chapter 4 Rerouting Schemes over MPLS Network34
4.1 All Rebuilt Rerouting Scheme34
4.2 Extended Rerouting Scheme37
4.3 LSP Rerouting Scheme39
Chapter 5 Modified Rerouting Schemes43
5.1 All Rebuilt Rerouting with Resource Reservation43
5.2 Extended Rerouting with Loop Removal44
5.3 LSP Rerouting with Resource Reservation44
Chapter 6 Simulation Results45
6.1 Network Model and Assumptions45
6.2 Simulation Results47
Chapter 7 Conclusion54
References57

[1] A. Viswanathan, N. Feldman, Z. Wang, R. Callon,”Evolution of Multiprotocol Label Switching”, IEEE Commun. Magazine, Vol. 36, No. 5, pp.165-173, May 1998
[2] Y. Rekhter, B. Davie, E. Rosen, G. Swallow, D. Farinscci, D. Katz, “Tag Switching Architecture Overview”, Proceedings of the IEEE, Vol. 85, No. 12, pp.1973-1983, Dec. 1997
[3] P. Boustead, J. Chicharo, G. Anido, “Scability and Routing Performance of Label Switching Networks”, IEEE GLOBECOM’98, Sydney,Australia, pp.3542-3552, Nov. 1998
[4] S. Lin, N. McKeown, “A Simulation Study of IP Switching”, ACM SIGCOMM’97, Cannes, France, pp.15-24, Sept. 1997
[5] C. Metz ”Aggregate Route-Based IP Switching”, Technical Report, IBM Corp., Mar. 1997
[6] S. Matsuzawa; K. Nagami, A. Mogi, T. Jinmei, H. Esaki, Y. Katsube, ” Architecture of cell switch router and prototype system implementation”, IEICE Trans. on Commun., Vol. E80-B, No. 8, pp.1227-1238, Aug. 1997
[7] C. Perkins, “IP Mobility Support”, IETF RFC 2002, Oct. 1996
[8] M. D. Abate, M. D. Marco, “Performance Evaluation of Mobile IP Protocols in a Wireless Environment”, IEEE ICC’98, ATLANTA, GA, USA, pp.1810-1816, June 1998
[9] K. Rauhala, “Baseline Text for Wireless ATM specifications”, ATM Forum wireless ATM Working group, July 1997
[10] Callon et al., “Multiprotocol Label Switching Architecture”, IETF Internet Draft, draft-ietf-mpls-arch-02.txt, July 1998.
[11] Callon et al., “Multiprotocol Label Switching framework”, IETF Internet Draft, draft-ietf-mpls-framework-02.txt, Nov. 1997.
[12] Y. Rekhter, E. Rosen, “Carrying Label Information in BGP-4”, IETF Internet Draft, draft-ietf-mpls-bgp4-mpls-02.txt, Feb. 1999
[13] D. Haskin, J. W. Stewart, ”Multiprotocol Extensions for BGP”, IETF Internet Draft, draft-stewart-bgp-multiprotocol-00.txt, June 1997
[14] N. Ken-ichi, N. Demizu, H. Esaki, P. Doolan, “VCID Notification over ATM link”, Internet Draft, draft-ietf-mpls-vcid-atm-01.txt, Aug. 1998
[15] K. McCloghrie, Y. Rekhter, E. Rosen, G. Swallow, P. Doolan, “Use of Label Switching With ATM”, Internet Draft, draft-davie-mpls-atm-01.txt, July 1998
[16] P. R. Calhoun, K. Peirce, “Layer Two Tunneling Protocol (L2TP)”, IETF Internet Draft, draft-ietf-pppext-l2tp-mpls-01.txt, July 1998
[17] A. Conta, P. Doolan, A. Malis, “Use of Label Switching on Frame Relay Networks”, IETF Internet Draft, draft-ietf-mpls-fr-03.txt, Nov.1998
[18] A. T. Tanenbaum, “Computer networks”, Prentice Hall, 3th Edition, 1996
[19] J. Ryan, “Multiprotocol Label Switching (MPLS)”, Ennovate Technology Guides Series, http://www.techguide.com/comm/secmpls.pdf, 1998
[20] P. Doolan, N. Feldman, A. Fredette, B. Thomas “LDP Specification”, IETF Internet Draft, draft-ietf-mpls-ldp-03.txt, Jan. 1999
[21] I. Widjaja, A. Elwalid, “Performance Issues in VC-Merge Capable MPLS Switches”, IETF Internet Draft, draft-widjaja-mpls-vc-merge-00.txt, July 1997
[22] Rosen et al., “MPLS Label Stack Encoding”, IETF Internet Draft, draft-ietf-mpls-label-encaps-03.txt, Sept. 1998
[23] B. Davie, L. Tony, Y. Rekhter, E. Rosen, “Explicit Route Support in MPLS”, IETF Internet Draft, draft-davie-mpls-explicit-routes-00.txt,
[24] E. C. Rosen, Y. Rekhter, D. Tappan, D. Farinacci, G. Fedorkow, L. Tony, C. Alex, “Label Switching: Label Stack Encodings”, IETF Internet Draft, draft-rosen-tag-stack-03.txt, July 1997
[25] Y. Katsube, Y. Ohba, N. Ken-ichi, “Two Modes of MPLS Explicit Label Distribution Protocol”, IETF Internet Draft, draft-katsube-mpls-two-ldp-00.txt, Sept. 1997
[26] D. O. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, J. McManus, “Requirements for Traffic Engineering Over MPLS”, IETF Internet Draft, draft-awduche-mpls-traffic-eng-00.txt, Apr. 1998
[27] J. Heinanen, E. Rosen, “VPN support with MPLS”, IETF Internet Draft, draft-heinanen-mpls-vpn-01.txt, Mar. 1998
[28] B. Davie, Y. Rekhter, E. Rosen, A. Viswanathan, V. Srinivasan, S. Blake, “Use of Label Switching With RSVP”, IETF Internet Draft, draft-ietf-mpls-rsvp-00.txt, Mar.1998
[29] G. Hagard, M. Wolf, “Multiprotocol label switching in ATM networks”, Ericsson, The Telecommun. Technology Journal, No.1, 1998
[30] CISCO, “MPLS Support in Cisco Products”, Packet Magazine, http://www.cisco.com/warp/public/784/packet/apr99/6a.html, Apr. 1999
[31] Y. Ohba, Y. Katsube, E. Rosen, P.Doolan, “MPLS Loop Prevention Mechanism Using LSP-id and Hop Count”, IETF Internet Draft, draft-ohba-mpls-loop-prevention-00.txt, March 1998
[32] A. Seneviratne, B. Sarikaya, “Cellular networks and mobile Internet”, Computer Commun., Vol. 21, No. 14, pp.1244-1255, Mar. 1998
[33] C. Perkins, “IP Mobility Support”, RFC 2002, Oct. 1996
[34] C. Perkins, S. D. B. Johnson, “Route Optimization in Mobile IP”, IETF Internet Draft, draft-ietf-mobileip-optim-07.txt, 20 Nov 1997
[35] S. Choe, Y. Kim, J. Kim, K. Chae, Y. Mun, “Rerouting scheme for handoff in wireless ATM”, Electronics Letters, 28th, Vol. 34, No. 34, pp.1076-1077, May 1998
[36] P. Mishra, M. Srivastava, “Effect of Connection Rerouting on Application Performance in Mobile Networks”, IEEE Trans. on Computers, Vol. 47, No. 4, pp.371-390, Apr. 1998
[37] R. Ramjee, T. F. La Porta, J. Kurose, D. Towsley, “Performance Evaluation of Connection Rerouting Schemes for ATM-Based Wireless Networks”, IEEE/ACM Trans. on Networking Vol. 6, No. 3, pp.249-260, June 1998
[38] C. K. Toh, “Performance Evaluation of Crossover Switch Discovery Algorithms for Wireless ATM LANs”, IEEE, INFOCOM’96, San Francisco, CA, USA, pp.1380-1387, Mar. 1996
[39] K. Jang, K. Kang, J. Shim, D. Kim, “Two Connection Rerouting Schemes For Wireless ATM Environment”, IEEE 6th ICUPC, N.Y. USA, pp.738-45, Feb. 1997
[40] J. Myore, V. Bharghavan, “A New Multicasting-Based Architecture for Internet Host Mobility”, Proceedings of ACM Mobicom, pp.161-172, Sep. 1996
[41] M. Stangel, V. Bharghavan, “Improving TCP Performance in Mobile Computing Environments”, IEEE ICC’98, Atlanta, GA, USA, pp.584-590, June 1998