1. A study of provision of protecting capability after link failure in WDM networks 在 WDM 網路下以 FIPP 保護環連續供給保護能力之研究 作 者 : 丁德榮 (Der-Rong Din) 賴薪吉 (Hsin-Chi Lai) 服務單位：國立彰化師範大學 報 告 者 ：賴薪吉 (Hsin-Chi Lai) 報告日期 : 2008/10/20

2. WDM Network @ NCUE NETLAB 6/13/2016 30-2 Outline  Introduction  Related Works  Problem Definition  Proposed Solutions  Cycle-Recovery Policy  Path-Recovery Policy  Simulation Results  Conclusions

3. WDM network  WDM network  Physical Topology  Virtual Topology WDM Network @ NCUE NETLAB 6/13/2016 30-3 Introduction 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 (a) Physical Topology(b) Virtual Topology virtual link lightpath physical link

4. WDM Network @ NCUE NETLAB 6/13/2016 30-4 Span p-cycles  Structure of p-cycles(1998) are formed in spare capacity layer of a mesh network, and are pre-connected unit-capacity cycles.  Every unit-capacity p-cycle, two units of working capacity can be carried on each straddler, this feature leads to tremendous efficiency.  P-cycles also retain the switching speed and simplicity of ring as the protection paths around the surviving portions of the cycle are pre- connected in advance and the only switching actions required take place at the end-nodes of the failure.  The shortcoming of p-cycle:  We must provide some spare-capacity for protection in advance (SBPP did not require spare-capacity in advance).  Because of above requirement, we can obtain very fast recovery speed and high quality of protection path (SBPP can’t). Introduction

5. Span failure restoration WDM Network @ NCUE NETLAB 6/13/2016 30-5 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 1 4 3 2 7 8 9 5 6 0 Introduction Span p-Cycle Straddling span On-cycle span

6. WDM Network @ NCUE NETLAB 6/13/2016 30-6 Failure-independent path-protecting (FIPP) p-cycles  Extension of the concept of span p-cycles to provide end-to- end path protection (not only span protection).  FIPP p-cycle is similar to SBPP protection, when two working paths are link disjoint, they can share common FIPP p-cycle.  In FIPP p-cycle, one link failure does not break more than one working path.  FIPP p-cycle retains the "ring-like speed" of span-protecting p-cycle while gaining the property of failure independence of the protection reaction for each path. Introduction

7. Structure of FIPP p-Cycles WDM Network @ NCUE NETLAB 6/13/2016 30-7 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 1 4 3 2 7 8 9 5 6 0 Notice: FIPP p-cycle must pass through end nodes of connections. Introduction DRS1 DRS2

8. WDM Network @ NCUE NETLAB 6/13/2016 30-8 FIPP p-cycles protection relation  On-cycle working path: FIPP p-cycle provides only one protection path for this connection to restore working path. Introduction 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 overlapping on FIPP p-cycle

9. WDM Network @ NCUE NETLAB 6/13/2016 30-9  Straddling working path: FIPP p-Cycle provides two protection paths for this connection to restore working path. Introduction 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 straddling on FIPP p-cycle FIPP p-cycles protection relation

10. WDM Network @ NCUE NETLAB 6/13/2016 30-10 Related Works  Recently, several studied relative to FIPP p-cycle have been proposed.  Given: Given physical topology 、 virtual topology and all working paths.  Goal: Find a set of FIPP p-cycles and minimize total cost of spare capacity on FIPP p-Cycles, and protect all working paths and ensure 100% single link failure restoration. Related Work

11. Schemes classification  The proposed schemes can classify into three catalog:  ILP scheme  Heuristic scheme  Mixed : ILP & heuristic scheme  Pure ILP scheme  FIPP-spare capacity placement (SCP)  FIPP column generation (CG)  FIPP joint capacity placement (JCP)  Heuristic scheme  FIPP iterative joint design (IJD)  Mixed : ILP & heuristic scheme  FIPP-disjoint routes set (DRS)  FIPP-SCP-iterative heuristic (IH) WDM Network @ NCUE NETLAB 6/13/2016 30-11 Related Work

12. Motivation & goal  The proposed researches all focus on “How to minimize total cost of spare capacity to build a WDM network and use FIPP p-Cycles to provide 100% restoration for single link failure”.  When many link failures occurred, working paths may break off and FIPP p-cycles may lose protecting capability.  Because of above reason, we focus on “When many link failures occurred, working paths can survive and corresponding FIPP p-cycles also keep full protecting capability”. WDM Network @ NCUE NETLAB 6/13/2016 30-12 Problem definition

13. Link failures 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 1 4 3 2 7 8 9 5 6 0 Failed 6/13/2016 30-13 Problem definition

14. WDM Network @ NCUE NETLAB 6/13/2016 30-14 Goal  Fixed & known  G p (V,E p ) : Physical Topology  G v (V,E v ) : Virtual Topology  P : Working Paths  Goal  Working paths that pass through physical link failure can survive from link failure and corresponding FIPP p-Cycles can keep full protecting capability, if possible. Problem definition

15. Evaluation Function  We use four evaluation function to show the recovery process is down well or bad.  Weavlength Efficient Ratio, WER  Restorable Connection Ratio, RCR  Non-restorable Connection Ratio, NCR  Recovery Time, RT WDM Network @ NCUE NETLAB

16. 6/13/2016 30-16  Assumption  Two adjacent nodes are connected by a bi-direction fiber.  Nodes in WDM network are equipped with wavelength convertible capability.  Physical topology of WDM network is two-connected.  TXs/RXs on nodes are tunable.  WDM network using FIPP p-cycle protection scheme are known, any two working paths that protected by the same FIPP p-cycle are link-disjoint.  Lightpaths between node pairs are fixed and known. Assumption Problem definition

17. WDM Network @ NCUE NETLAB 6/13/2016 30-17 Ideas of recovery  How to adjust current WDM network to resist physical link failures ?  After appropriate adjustment, working paths can survive from link failure and corresponding FIPP p-cycles can keep full protecting capability.  Our ideas are to finding a new path from source and sink:  recovery the broken FIPP p-Cycle  recovery the working path of connection request.  Owing to above ideas, two recovery schemes are developed.  Cycle-Recovery Policy (abbreviated as CRP)  Path-Recovery Policy (abbreviated as PRP) Proposed Solution

18. WDM Network @ NCUE NETLAB 6/13/2016 30-18  Pre-processing ：  For each connection, using maximum flow concept to find some link-disjoint paths as backup path set.  For all possible combinations of two selected paths in backup path set, join these paths to form a cycle, and construct the candidate cycle set.  We define three flag represent relation between FIPP p-cycle and connection request below :  F ： this connection request was blocked.  W ： working path without protection path, it can not recovery immediately when link failure occurred.  R ： working path with at lease one protection path.  When link failure occurred, only flag of connection request equal to R need to activate recovery scheme, others are blocked. Recovery Schemes Pre-processing

19. WDM Network @ NCUE NETLAB 6/13/2016 30-19  Connection request use default protection path be new working path, release resource that hold by old working path, then find a path to recovery broken FIPP p-Cycle. Recovery Schemes Concept of Cycle-Recovery Policy 1 4 3 2 7 8 9 10 5 6 0 (a) Link 3-10 failure 1 4 3 2 7 8 9 10 5 6 0 (b) After cycle-recovery

20. WDM Network @ NCUE NETLAB 6/13/2016 30-20  Step 1 ：  If working paths and protection path are link disjoint then go to Step 2(1), else go to Step 2(3). Recovery Schemes Cycle-Recovery Policy Step 1 1 4 3 2 7 8 9 10 5 6 0 P1=(6-8-0) P2=(3-7-8) P3=(3-10-6) P(DC 3,1 )=(3-5-6) P(DC 2,1 )=(3-2-0-8)

21. WDM Network @ NCUE NETLAB 6/13/2016 30-21  Step 2 ： (Recovery)  (1)If exist a path from backup path set and link disjoint with residual working paths. using protection path as new working path and new path to recovery FIPP p-Cycle. After cycle recovery, go to Step 5 case 3.  (2)Find a suitable path from current network, and link disjoint with residual working paths. using protection path as new working path and new path to recovery FIPP p-Cycle. After cycle recovery, go to Step 5 case 3.  (3)Because of exist some link overlap, remove this connection from protected set of FIPP p-Cycle. Recovery Schemes Cycle-Recovery Policy Step 2

22. WDM Network @ NCUE NETLAB 6/13/2016 30-22 Recovery Schemes Cycle-Recovery Policy 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0 Recovery Step 2(1) Step 2(3) 1 4 3 2 7 8 9 10 5 6 0 Non-link disjoint Remove 1 4 3 2 7 8 9 10 5 6 0

23. WDM Network @ NCUE NETLAB 6/13/2016 30-23  Step 3 ： (Merge)  Chose a cycle c from DCi and find a path from backup path set or find a suitable path from current network, this path must be link-disjoint with residual working paths that are protected by cycle c.  If a suitable path exist, using this path to be new working path and go to Step 5 case 3. Recovery Schemes Cycle-Recovery Policy Step3 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0

24. WDM Network @ NCUE NETLAB 6/13/2016 30-24  Step 4 ： (Redeploy)  According to current residual resources of network, and find a suitable path as new working path. If path not exist, go to Step5 case 1.  Find a cycle from candidate cycle set or find a cycle from current network, and let this cycle as new FIPP p-cycle to protect working path. If cycle was found then go to Step5 case 3, else Step5 case 2. Recovery Schemes Cycle-Recovery Policy Step4 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0

25. WDM Network @ NCUE NETLAB 6/13/2016 30-25  Step 5 ： (Classify)  According to relation between FIPP p-Cycle and connection request, we set protection flag for connection: Case 1 flag = F ： this connection request was blocked. Case 2 flag = W ： working path is not protected by any FIPP p-cycle. Case 3 flag = R ： working path is protected by FIPP p-cycle. Cycle-Recovery Policy Step5 Recovery Schemes

26. WDM Network @ NCUE NETLAB 6/13/2016 30-26  Connection request use default protection path be impermanent working path, release resource that hold by old working path, then find a path to recovery broken working path.  Difference from PRP policy and CRP policy :  Two policies both find new path, but path for CRP was to recovery FIPP p-Cycle; on the other hand, path for PRP was to recovery working path.  We just list different part of algorithm below, un-list part of algorithm was as same as CRP algorithm. Concept of Path-Recovery Policy Recovery Schemes

27. WDM Network @ NCUE NETLAB 6/13/2016 30-27  Step 2 ：  If exist a path from backup path set or find a suitable path from current network, and link-disjoint with residual working paths. using new path to recovery FIPP p-Cycle.  After path recovery, go to Step 5 case 3.  Otherwise, because of exist some link overlap, remove this working path from protected set of FIPP p-Cycle. Path-Recovery Policy Step2 Recovery Schemes 1 4 3 2 7 8 9 10 5 6 0 1 4 3 2 7 8 9 5 6 0

28. WDM Network @ NCUE NETLAB 6/13/2016 30-28 Simulations  We use C++ and Boost Graph Library(BGL) to coding our platform and recovery algorithms, simulations are run on Windows XP with core dual 1.66GHz and 1.5G RAM.  We use COST239 network topology as physical topology, and 19 connections are fixed and partition to some group. 1 4 3 2 7 8 9 10 5 6 0 COST239 network

29. WDM Network @ NCUE NETLAB 6/13/2016 30-29 Simulations

30. Conclusions  In this paper, we propose two recovery policies: cycle- recovery policy and path-recovery policy.  By perform recovery policy, FIPP p-cycle can keep full protecting capability to protect some working paths.  We may perform some adjusting process to balance number of working paths are protected by FIPP p-cycle.  If new connections are arrived, the problem how to route and protect those connections will be studied in future. WDM Network @ NCUE NETLAB