Design of CapEx-Efficient IP-over-WDM Network using Auxiliary Matrix based Heuristic

IEEE ANTS 2014 1570023335 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 60 61 62 63 64 65 Design of CapEx-Efficient IP-over-WDM Network using Auxiliary Matrix based Heuristic Suman Kr. Dey and Aneek Adhya Department of Electrical Engineering Indian Institute of Technology Patna, India, Patna-800 013 skdey@iitp.ac.in, aneek@iitp.ac.in Abstract In this paper, we propose an auxiliary matrix based CapEx-efficient heuristic (AM-CH) to provision network equipment for IP-over-WDM (IPoWDM) network with an objective to minimize the total CapEx of the network. Employing the heuristic, we jointly solve regenerator placement problem and traffic grooming problem. We consider a realistic network infrastructure where all network equipment are considered to be bidirectional and all WDM equipment are considered with finite maximum transparent distance limits. We employ AM-CH scheme integrated with non-bypass, direct bypass and multi-hop bypass techniques. It is observed that AM-CH scheme integrated with multi-hop bypass technique significantly minimizes CapEx over AM-CH scheme integrated with non-bypass or direct bypass technique. Index Terms IP-over-WDM network, CapEx efficiency, bidirectional. I. INTRODUCTION The objective of CapEx-efficient IP-over-WDM (IPoWDM) network design is to minimize the total capital expenditure (CapEx) of network (even though maintaining the desired network performance) so that network service providers can increase revenues by offering various services to the users at affordable prices. Similar to other existing studies (e.g., [1] [6]), in this study as well, we consider CapEx as the cost of network equipment only. Bypassing the transit traffic in optical layer instead of switching in IP layer may reduce the number of core IP router ports, thereby significantly reducing the CapEx [1] [3]. In [4], optimal placement of regenerators and wavelength converters are explored for designing impairment-aware CapExefficient optical transport network with due consideration of physical-layer heterogeneity (e.g., variable amplification span distance, amplifier types, fiber types, attenuation coefficients). In [5], optimal placement of transponders, muxponders and WDM multiplexers are considered for CapEx minimization. In [6], the authors propose optimization and heuristic solutions to reduce CapEx, by minimizing the number of optical amplifiers in a network which supports multicasting services in optical domain. Traffic routing may be implemented in IPoWDM network using two approaches: lightpath bypass and non-bypass [7]. In bypass approach, traffic transmitted through a lightpath is directly switched at intermediate nodes through bypass in optical domain. In contrast, in non-bypass approach, lightpath entering any intermediate node is necessarily terminated, i.e., the traffic arriving through the lightpath is electronically processed and forwarded by IP router located at the intermediate node. Traffic routing may employ two grooming strategies: single-hop grooming and multi-hop grooming [8], [9]. In single-hop grooming, traffic is routed between source and destination nodes of traffic demand through a single lightpath, while in multi-hop grooming, traffic is allowed to be routed between source and destination nodes through concatenated multiple lightpaths. Thus, multi-hop grooming is the generalized case of single-hop grooming [9]. Bypass approach with single-hop grooming is refereed to as direct bypass, while bypass approach with multi-hop grooming is refereed to as multi-hop bypass [7]. In this study, we consider a realistic network infrastructure where transmission of optical signal through WDM equipment (e.g., muxponder, regenerator, OXC, WDM terminal, OLA) are constrained by maximum transmission distance (MTD) (i.e., the maximum distance optical signal can be transmitted without regeneration) [1]. All network equipment are considered to be bidirectional. In particular, we propose auxiliary matrix based CapEx-efficient heuristic (referred to as AM-CH) integrated with non-bypass, direct bypass and multi-hop bypass techniques and study their performances. This paper is organized as follows. Section II describes the model of IPoWDM node architecture. Section III explains CapEx estimation model for IPoWDM network, while Section IV describes AM-CH scheme. Section V presents numerical results to evaluate the 1

performance of AM-CH integrated with non-bypass, direct bypass and multi-hop bypass techniques. Finally, we conclude the paper in Section VI. II. NODE ARCHITECTURE Fig. 1 presents a typical IPoWDM node architecture, where a core IP router connected with an OXC in optical layer grooms low-rate traffic from access routers. IP router has two main building blocks: basic structure and physical-layer interfaces [1]. Basic structure consists of router chassis, switching fabric, power supplies, cooling facilities, and control and management plane software, whereas physical-layer interfaces represent the ports accommodated into slots [1]. Basic structure offers limited number of bidirectional slots to connect bidirectional slot cards that may support different types of port cards with different granularity and interface technology (e.g., STM-16, STM-64, STM- 256 packet over SONET/SDH (PoS), 1-Gigabit Ethernet (GE), 10-GE) [1]. A port card occupies the whole capacity of a slot card. Based on the capacity of a port and the overall capacity of a port card, a port card may accommodate more than one port. In this paper, the integrated structure comprising a slot card and a port card is referred to as a line card (LC). Fig. 1. A typical IPoWDM node architerture. In this node architecture, 4 10 GE port cards are employed at the access side and network side (NS) of core router. Each port is equipped with a shortreach interface, which in turn is connected with a long-reach (LR) muxponder [1], [2]. The muxponder multiplexes lower-rate signals from ports to a higher data-rate lightpath (having a capacity of 40 Gbps). Hence, one network-side LC (NSLC) and one muxponder are required at each end of a lightpath. Selected nodes are equipped with bidirectional 3R (re-timing, reshaping, re-amplification) regenerators performing signal regeneration through optical-electrical-optical conversion. A fiber 1 interconnecting two adjacent nodes accommodates a bidirectional WDM terminal at its each 1 Here, fiber represents bidirectional fiber consisting of two unidirectional fibers in opposite direction, unless stated otherwise. end. A WDM terminal is equipped with an unidirectional demultiplexer connected with a pre-amplifier and an unidirectional multiplexer connected with a post-amplifier [1]. In order to amplify optical signal in both direction, bidirectional optical line amplifiers (OLAs) consisting of two unidirectional amplifiers are placed on fibers [1]. III. CAPEX ESTIMATION MODEL Overall CapEx for IPoWDM network may be estimated by employing the following approach where the cost of all equipment located at the nodes (i.e., IP router, OXC, muxponder and regenerator) and the fibers (i.e., WDM terminal and OLA) are separately computed. The cost for installing fibers is not included in the fiber cost, since fiber-connectivity for the given network is considered to be fixed. Finally, combining the cost of equipment located at nodes and fibers, the overall CapEx for the network is computed. A fiber is made active (i.e., WDM terminals and OLAs are installed in a fiber and switched on) only when one (or more) lightpath is required to be accommodated in the fiber. As WDM terminals and OLAs are bidirectional, an active unidirectional fiber between two nodes signifies that the unidirectional fiber in the opposite direction is also active. As a NSLC is connected to a muxponder, equal number of muxponders and NSLCs are employed at a node. Two lightpaths can simultaneously be regenerated by a bidirectional regenerator. Since, cost of OXC at a node depends on physical degree of the node and number of wavelength support by a fiber, OXC cost is considered to be fixed [1]. IP router cost is also divided into two parts, namely, the basic structure cost and the LC cost. We assume that all IP routers in the network are equipped with same basic structure (with same switch fabric capacity, slot capacity etc.). Therefore, all nodes in the network have the same basic structure cost. As total number of LCs required at access-side of an IP router depends on the total incoming and outgoing traffic at the access routers, the cost for LCs required at access side (i.e., ASLC cost) is fixed for given static traffic demand. Thus, the cost of a node only depends on employed NSLC, muxponder and regenerator at the node. The notations used to represent the cost of OXC with degree d, basic-structure, slot card, port card, muxponder, regenerator, OLA and WDM terminal arec d oxc, C bs, C s, C p, C m, C reg, C ola and C wdmt, respectively. To explain the cost model, a linear network topology (Fig. 2) is taken as an example, wherein for simplicity, it is assumed that all fibers have same length, with A number of OLAs placed in each fiber. Lightpath LP 1 with traffic t BC is set up between nodes B and C. Another lightpath (namely, LP 2 ) with traffic t CA is set up between nodes C and A. This lightpath is 2

Fig. 2. An example linear IPoWDM network. Regenerator is employed at a node only when regeneration is required. also regenerated at node B. It is observed that one NSLC and one muxponder are required at each node. However, only one regenerator is required at node B. The cost of nodes A, B and C (represented by C A, C B and C C respectively) may be calculated as C A = C l +C m +(C bs +C l t CA /t al +C 2 oxc) C B = C l +C m +C reg +(C bs +C l t BC /t al +C 2 oxc ) C C = C l +C m +(C bs +C l max(t BC,t CA ) t al +C 2 oxc ) (1) where C l is the cost of a LC (i.e., C l = C s + C p ). max(t BC,t CA ) indicates the maximum value between t BC and t CA, and t al indicates the traffic handling capacity of ASLC. Thus, cost expended at the nodes (i.e., C node ) may be calculated as C node = C A +C B +C C (2) Since two fibers (i.e., AB and BC) are active in the given example, the cost expended at the fibers (i.e., C fiber ) is C fiber = 2(A C ola +2C wdmt ) (3) Total CapEx (i.e., C total ) for the example network wherein two lightpaths have been set up may be calculated as C total = C node +C fiber (4) IV. CAPEX-EFFICIENT HEURISTIC In this section, we explore AM-CH scheme. First, the method to construct an auxiliary matrix (AM) is described. Subsequently, AM-CH scheme is described. A. Auxiliary Matrix (AM) An IP router is represented by two auxiliary nodes (ANs): IP router NS input node (R in ) (representing NS input slots) and IP router NS output node (R out ) (representing NS output slots). An OXC is also represented by two ANs: OXC input node (O in ) (representing input ports of OXC) and OXC output node (O out ) (representing output ports of OXC). As one node of IPoWDM network consists of one IP router and one OXC, each node may be represented by a combination of four ANs. In reference to a given node with index n, the corresponding ANs (R in, R out, O in and O out ) are represented in the auxiliary graph (AG) with indices (4n+0), (4n+1), (4n+2) and (4n+3), respectively. We construct an AG by linking ANs through unidirectional auxiliary edges (AEs). As signal is switched along an AE, one or many operations (e.g., grooming, regeneration, optical bypass) are performed and the corresponding cost value of the equipment involved to perform the operation is considered as the weight of the AE. As stated in Section III, the fixed component of CapEx (i.e., fixed-cost) due to the cost of basic structure, ASLC and OXC is not considered in the AE weights. We construct AM by representing AG in the form of a table. As for an example, Fig. 3(a) shows a linear network, where nodes having indices n 0 and n 1 are connected through a fiber. A lightpath from node n 0 to node n 1 is set up. For a given traffic, the corresponding AG is shown in Fig. 3(b), where source and destination ANs of the lightpath are represented by (4n 0 +1) and (4n 1 + 0), respectively. In reference to the AG in Fig. 3(b), AM is shown in Table I(c); two representative sections of AM with ANs lying at the same node or at different nodes are shown in Table I(a) and Table I(b), respectively. Partial tables (Table I(a) and Table I(b) with size [4 4]) is used to construct the complete AM (with size [4N 4N]) for a network consisting of N nodes. (a) An example network with a lightpath set up from IP router at node n 0 to IP router at node n 1. Fig. 3. (b) AG corresponding to Fig. 3(a). AG for an example linear network. AE weights used in Table I are as follows: INF indicates the unavailability of any AE between ANs (i.e., the weight of the AE is infinity). The diagonal elements of Tables I(a) and I(b) are made INF to restrict traffic to form self-loop. C 1 represents the equipment cost for switching traffic from R in to R out of the same node. Since, basic structure cost of core router is included in 3

TABLE I AM WITH SECTIONAL AND COMPLETED FORM (a) ANs lie at the same node (with index n 0 ) R in R out O in O out (4n 0 + 0) (4n 0 + 1) (4n 0 + 2) (4n 0 + 3) R in (4n 0 + 0) INF C 1 INF INF R out (4n 0 + 1) INF INF INF C 2 O in (4n 0 + 2) C 3 INF INF C 4 O out (4n 0 + 3) INF INF INF INF (b) ANs lie at two different nodes (with indices n 0 and n 1 ) R in R out O in O out (4n 1 + 0) (4n 1 + 1) (4n 1 + 2) (4n 1 + 3) R in (4n 0 + 0) INF INF INF INF R out (4n 0 + 1) C 5 INF INF INF O in (4n 0 + 2) INF INF INF INF O out (4n 0 + 3) INF INF C 6 INF n 0 = 0 n 1 = 1 (c) The complete AM n 0 = 0 n 1 = 1 0 1 2 3 4 5 6 7 Rin Rout Oin 0 R in INF C 1 INF INF INF INF INF INF 1 R out INF INF INF C 2 C 5 INF INF INF 2 O in C 3 INF INF C 4 INF INF INF INF 3 O out INF INF INF INF INF INF C 6 INF 4 R in INF INF INF INF INF C 1 INF INF 5 R out C 5 INF INF INF INF INF INF C 2 6 O in INF INF INF INF C 3 INF INF C 4 7 O out INF INF C 6 INF INF INF INF INF fixed-cost, no equipment cost is incurred to groom traffic at IP router. Therefore, C 1 = 0 for AM-CH with multi-hop bypass (or non-bypass). However, C 1 = INF for AM-CH with direct bypass to avoid grooming at intermediate node. C 2 represents the equipment cost for switching traffic fromr out to O out via O in (where all the ANs lie at the same node), for a new lightpath to be set up and the traffic to be accommodated in the lightpath. Thus, C 2 represents the cost of a NSLC and a muxponder (the cost for switching traffic through OXC is included in fixed-cost). C 2 = 0, in case egress logical degree (i.e., the number of outgoing lightpaths) is less than ingress logical degree (i.e., the number of incoming lightpaths) (i.e., the NSLCs and muxponders previously employed to terminate existing lightpaths at the node, can be reused to originate new lightpath from the node); else C 2 = (C l + C m ) (i.e., new NSLC and muxponder are required to originate new lightpath from the node); else C 2 = INF (i.e., free NSLC is not available at the node). C 3 represents the equipment cost for switching traffic from O in to R in via O out (where all the ANs lie at the same node), for a new lightpath to be set up and the traffic to be accommodated in the lightpath. Thus, C 3 represents the cost of a NSLC and a muxponder (the cost for switching traffic through OXC is included in fixed-cost). Oout Rin Rout Oin Oout Therefore,C 2 and C 3 correspond to the equipment cost depending on the traffic flows in opposite direction. C 3 = 0, in case ingress logical degree is less than egress logical degree at the node; else C 3 = (C l +C m ) (i.e., new NSLC and muxponder are required to terminate new lightpath at the node); else C 3 = INF (i.e., free NSLC is not available at the node). C 4 represents the equipment cost for switching traffic (through signal regeneration or bypass) from O in to O out of the same node, for a new lightpath to be set up and the traffic to be accommodated in the lightpath. C 4 = C reg, if a new regenerator is employed at the node for regeneration of lightpath; else, C 4 = 0, if a new regenerator is not required due to bidirectional nature of regenerator or lightpath bypass through OXC at the node. In non-bypass technique, C 4 is always considered to be INF, so that traffic is always processed electronically at IP router. C 5 represents the equipment cost for switching traffic (through existing lightpath) from R out to R in, which lie at two different nodes. C 5 = INF, if a lightpath with free bandwidth between the ANs is not available to switch the traffic; else C 5 = 0 (i.e., a lightpath exists between the ANs with sufficient free bandwidth and cost incurred to switch traffic through the lightpath is zero). C 6 represents the fiber-cost, (i.e., the cost for switching traffic from O out to O in which lie at two different nodes, for a new lightpath to be set up and the traffic to be accommodated in it). C 6 = INF, if no fiber exists between the ANs; else C 6 = (A lm C ola +2C wdmt ) (if fiber needs to be activated); else C 6 = 0 (if already fiber has been activated). B. Auxiliary Matrix based CapEx-efficient Heuristic (AM-CH) In AM-CH scheme (Algorithm 1), the largest traffic element (i.e.,λ smaxdmax ) from traffic matrix is chosen at a time and the corresponding source AN and destination AN are determined. In case, the traffic amount is more than lightpath capacity (represented as B), the B amount traffic is selected as Temp, while the remaining traffic amount (i.e., λ smaxdmax B) is placed in the corresponding location of the traffic matrix. Otherwise, the whole traffic amount is selected as Temp and the corresponding location in traffic matrix is set to zero. Depending on Temp, all AE weights are computed based on non-bypass (or direct bypass or multi-hop bypass) technique considering that the traffic amount is needed to be routed along the AEs. Thus, the AG and the AM are constructed for Temp. Using the AM, the least-weight (i.e., the shortest) path for Temp is computed from source AN to desti- 4

Algorithm 1: AM-CH scheme 1 Step 1 : Find largest traffic element (λ smaxdmax ) in traffic matrix [λ sd ] where source node = s max and destination node = d max; 2 Step 2 : Source AN (as max) = 4s max + 1 and destination AN (ad max) = 4d max + 0; 3 Step 3 : if (λ smaxdmax > B) then 4 Temp = B and set λ smaxdmax = λ smaxdmax B; 5 else 6 Temp = λ smaxdmax and set λ smaxdmax = 0; 7 end 8 Step 4 : Construct AM for Temp based on non-bypass or direct bypass or multi-hop bypass technique; 9 Step 5 : Find shortest path between as max and ad max using AM; 10 Step 6 : if (Number of new lightpaths to be set up > 0) then 11 if (WCC is satisfied for all new lightpaths) then 12 for (all new lightpaths to be set up) do 13 Find regenerator position for the lightpath; 14 Employ all network equipment to set up the lightpath; 15 Route T emp through the lightpath; 16 Update network information; 17 end 18 else 19 Go to Step 5 to find higher order shortest-weight path; 20 end 21 end 22 Step 7 : if (Number of lightpaths to be reused > 0) then 23 for (all lightpaths to be reused) do 24 Route T emp through the lightpath; 25 Update network information; 26 end 27 end 28 Step 8 : Repeat Step 1 to Step 7 until all traffic elements become zero; 29 Step 9 :Compute CapEx using network information; nation AN. The path indicates existing lightpaths to be reused and/or new lightpaths to be set up to route Temp. If new lightpaths are required to be set up, wavelength continuity constraint (WCC) for all new lightpaths is checked. If WCC is satisfied, regeneration locations for all new lightpaths are computed. Thereafter, new lightpaths are set up and Temp is routed. Thereafter, network information 2 is updated. However, if the shortest path is not feasible due to WCC not being satisfied, higher order shortest path is selected and the process continues until a successful routing path for Temp is found. If existing lightpaths are reused to route Temp, network information is also updated. All traffic elements are routed using the process discussed above. Finally, the traffic matrix becomes zero. CapEx (including the fixed-cost) of network is computed by summing the cost of all equipment employed in the network (as obtained from network information database). V. RESULTS AND DISCUSSION To evaluate performance of AM-CH scheme integrated with non-bypass, direct bypass and multi-hop bypass techniques, we consider the 24-node USNET network [7, Fig. 3(c)] with 43 fibers, where each fiber is assumed to support 40 wavelengths in each direction. Wavelength capacity is taken to be 40 Gbps. We use 2 Network information signifies database for free resources in the network and detailed information regarding all existing lightpaths. a static traffic demand matrix, which is constructed by randomly picking 120 source-destination (s-d) pairs (i.e., average of five s-d pairs for each node) and allotted traffic randomly from a range [1, 20] Gbps by using uniform distribution. Other s-d pairs in the traffic matrix are allotted traffic randomly from a range [1, 5] Gbps by using uniform distribution. Since, wavelength converters are not available at nodes, WCC needs to be satisfied for lightpaths. Two adjacent OLAs are separated by a distance of 80 km. Table II represents the relative cost of various network equipment, normalized to the cost of a 10 Gbps longhaul transponder with MTD of 750 km [2]. We consider that all network equipment are bidirectional in nature and MTD of WDM equipment is 1500 km. TABLE II NORMALIZED COST VALUES FOR NETWORK EQUIPMENT [1] Equipment Normalized cost OXC, degree d (2<d 5), 100%, 40 channel system 8.33 d + 2.5 IP router basic structure: 1.28 Tbps capacity, 40 Gbps capacity per slot 111.67 1.92 Tbps capacity, 40 Gbps capacity per slot 140.83 Slot card, 40 Gbps capacity 9.17 Port card, 4 10 GE, LR (1550 nm, 80 km reach) 4.2 Muxponder, 40 G (10G 4), ELH (1500 km reach) 6.05 Regenerator, 40 G, ELH (1500 km reach) 7.24 OLA, 80 km span, ELH (1500 km reach) 2.77 WDM terminal, 40 channel, ELH (1500 km reach) 7.5 TABLE III TOTAL EQUIPMENT COUNT FOR AM-CH WITH NON-BYPASS, DIRECT BYPASS AND MULTI-HOP BYPASS TECHNIQUES Technique LC Muxponder Regenerator WDM terminal OLA Non-bypass 330 263 0 62 105 Direct bypass 619 552 100 84 141 Multi-hop bypass 284 217 13 48 77 AM-CH scheme provides detailed information related to routing and wavelength assignment, and regeneration locations for each lightpath. It also provides solution for traffic grooming problem. Table III shows the total number of different equipment (i.e., LC, muxponder, regenerator, WDM terminal and OLA) employed in the network, when the network is designed for non-bypass, direct bypass and multi-hop bypass techniques. Since, traffic for any s-d pair is processed by each intermediate IP router in nonbypass technique, no regenerator is required in this technique. The numbers of different equipment (excluding regenerator) employed using non-bypass technique are comparatively large compared to multi-hop bypass technique. It is also observed that significantly large number of equipment are employed for direct bypass compared to non-bypass and multi-hop bypass techniques. Although USNET topology has 43 fibers, the total number of active fibers for non-bypass, direct bypass and multi-hop bypass techniques are 31, 42 and 24, respectively. 5

TABLE IV COST DISTRIBUTION IN DIFFERENT TYPE OF EQUIPMENT FOR NON-BYPASS, DIRECT BYPASS AND MULTI-HOP BYPASS TECHNIQUES Technique IP Router OXC Muxponder Regenerator WDM terminal OLA Non-bypass 7092.18 776.38 1591.15 0 465 290.85 Direct bypass 10956.1 776.38 3339.6 724 630 390.57 Multi-hop bypass 6477.16 776.38 1312.85 94.12 360 213.29 Table IV shows the cost distribution of different types of equipment in IPoWDM network designed using AM-CH scheme integrated with non-bypass, direct bypass and multi-hop bypass techniques. It is observed that, for all techniques, the highest percentage of CapEx takes place at IP routers, while the other equipment contribute the remaining CapEx. Number of equipment 30 20 10 LC (non-bypass) LC (DB) LC (MHB) Muxp. (non-bypass) Muxp. (DB) Muxp. (MHB) Reg. (non-bypass) Reg. (DB) Reg. (MHB) 0 N0 N4 N8 N12 N16 N20 N23 Node index Fig. 4. Equipment required at each node for non-bypass, direct bypass (DB) and multi-hop bypass (MHB) techniques. Fig. 4 shows the distribution of different equipment (LC, muxponder and regenerator) at different nodes for non-bypass, direct bypass and multi-hop bypass techniques. It may be observed that the number of regenerators required at each node for direct bypass technique compared to other two techniques are large. In general, the numbers of LCs and muxponders employed at each node (barring a few nodes) for direct bypass technique are large compared to the other two techniques. In case of non-bypass technique, higher number of LCs and muxponders are required at the nodes with indices 11 and 15 (i.e., N11 and N15), compared to the other two techniques. TABLE V TOTAL CAPEX FOR NON-BYPASS, DIRECT BYPASS AND MULTI-HOP BYPASS TECHNIQUES FOR DIFFERENT TRAFFIC SCALING FACTORS Technique Traffic scaling factor 1 1.5 2 2.5 Non-bypass 10215.56 13427.43 16014.23 18651.78 Direct bypass 16816.65 17177.65 18265.25 Infeasible Multi-hop bypass 9233.8 10540.33 12580.8 14062.45 Table V shows the total CapEx for non-bypass, direct bypass and multi-hop bypass techniques for different traffic scaling factors. Starting from the initial traffic demand matrix, results are evaluated up to a traffic scaling factor of 2.5. We consider that IP router basic structure consist of 32 slots to support traffic with scaling factors of 1 and 1.5. However, in order to accommodate traffic with scaling factors of 2 and 2.5, we consider IP router basic structure with 48 slots. It may be observed that multi-hop bypass technique offers minimum CapEx for any traffic scaling factor in comparison with other two techniques. When traffic scaling factor becomes 2.5, network design using direct bypass technique becomes infeasible as total traffic in traffic demand matrix can not be accommodated due to the unavailability of slots. VI. CONCLUSION In this study, we explore auxiliary matrix based capacity planning scheme (i.e., AM-CH) integrated with non-bypass, direct bypass and multi-hop bypass techniques for IPoWDM network and evaluate total CapEx for designing the network. We employ a realistic network infrastructure where network equipment are considered to be bidirectional, keeping into consideration the MTD of WDM equipment. AM-CH scheme provides detailed information regarding the number of equipment to be employed at different nodes and fibers. Thus, the locations for regenerator placement are also specified. It is observed that the total CapEx of IPoWDM network for multi-hop bypass technique is always the least than non-bypass and direct bypass techniques. REFERENCES [1] R. Huelsermann, M. Gunkel, C. Meusburger, and D. A. Schupke, Cost modeling and evaluation of capital expenditures in optical multilayer networks, J. Opt. Netw., vol. 7, no. 9, pp. 814-833, Sept. 2008. [2] E. Palkopoulou, D. A. Schupke, and T. Bauschert, Energy efficiency and CAPEX minimization for backbone network planning: is there a tradeoff?, in IEEE ANTS, pp.1-3, Dec. 2009. [3] S. Sengupta, V. Kumar, and D. Saha, Switched optical backbone for cost-effective scalable core IP networks, IEEE Commun. Mag., vol. 41, no. 6, pp. 60-70, Jun. 2003. [4] G. Shen, Y. Shen, and H. P. Sardesai, Impairment-aware lightpath routing and regenerator placement in optical transport networks with physical-layer heterogeneity, J. Lightw. Technol., vol. 29, no. 18, pp. 2853-2860, Sept. 2011. [5] M. Scheffel, R. G. Prinz, C. G. Gruber, A. Autenrieth, and D. A. Schupke, Optimal routing and grooming for multilayer networks with transponders and muxponders, in IEEE GlobeCom, pp. 1-6, Nov. 2006. [6] A. M. Hamad and A. E. Kamal, Optical amplifiers placement in WDM mesh networks for optical multicasting service support, IEEE J. Opt. Netw., vol. 1, no. 1, pp. 204-221, Jun. 2009. [7] G. Shen and R. S. Tucker, Energy-minimized design for IP Over WDM networks, J. Opt. Commun. Netw., vol. 1, no. 1, pp. 176-186, Jun. 2009. [8] K. Zhu and B. Mukherjee, Traffic grooming in an optical WDM mesh network, J. Sel. Areas Commun., vol. 20, no. 1, pp. 122-133, Jan. 2002. [9] W. Yao, G. Sahin, M. Li, and B. Ramamurthy, Analysis of multihop traffic grooming in WDM mesh networks, Opt. Switching Netw., vol. 6, no. 1, pp. 64-75, Jan. 2009. 6