JP2006148396A - Awg single hop wdm network structure method, program thereof, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a scalability in an AWG network by deriving the number of optimum arrangement couplers to minimize the total number of transceivers, while satisfying a given delay restricting condition. <P>SOLUTION: A calculation method is provided, by which the number of the optimum arrangement couplers to minimize the total number of the required transceivers is calculated within a range to satisfy a permission packet transfer delay time which is given from a given traffic amount in a network with a structure for connecting a plurality of nodes to an AWG after aggregation by the couplers in an AWG single hop WDM network with a MAN for using the AWG for a hub node as an object. The minimum value of an FSR for satisfying given permission average packet transfer delay and the maximum number of storable nodes in the case are obtained. Respective values where the total number of the transceivers is minimized are adopted as an optimum number of POP core wire and the number of arrangement couplers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a plurality of nodes in an AWG single-hop WDM (Wavelength-Division Multiplexed) network for MAN (Metropolitan Area Network) using AWG (Arrayed-Waveguide Grating) as a hub node are aggregated by a coupler G. In the network configured to connect to the network, an optimum FSR (Free Spectral Range) value and the number of installed couplers that minimize the total number of transceivers within a range that satisfies a given allowable packet transfer delay time from a given traffic amount, The present invention relates to a method for calculating the number of required lines of POP (Point-Of-Presence), and the program and a recording medium on which the program is recorded.

Gigabit Ethernet (registered trademark) (1000BASE-T, which is even faster than 100BASE-T and has a maximum of 1 Gbps, has also appeared. In Ethernet (registered trademark), all users share one transmission path, so it transmits. In the local area network (LAN) and wide area network (WAN) due to the introduction of WDM transmission and high-capacity routers or optical cross-connects. The transmission capacity continues to improve dramatically. However, a metropolitan area network (MAN) intervening between the LAN and the WAN is still the mainstream of SONET / SDH (Synchronous Optical Network / Synchronous Digital Hierarchy).
SONET itself does not have a switching function like ATM, and is dedicated to transmitting traffic between two points. And, it is composed of double rings with opposite communication directions. Normally, one ring and the multiplexing device transmit traffic, and when the optical fiber cable is cut during operation or the multiplexing device breaks down, it is instantaneous. The other ring is replaced and the network continues to operate.

  However, there is concern about the node bottleneck associated with electrical processing against the sudden increase in traffic in the metro area. Therefore, MAN is expected to introduce an all-optical network that eliminates packet store-and-forward at nodes and performs cut-through transmission with optical signals as they are. However, since MAN is more strict with respect to cost, it is important to operate an all-optical network that suppresses both facility cost (CAPEX) and control cost (OPEX).

  A single-hop WDM network that forms a star topology by providing a single hub node in the center and connecting all the nodes to the hub node has attracted attention as an all-optical network architecture in MAN. In a single-hop WDM network, packet transfer between all nodes is performed directly via the hub node without passing through other nodes, so there is an advantage that routing and signaling are unnecessary and packet transfer delay is small. . In addition, since a passive optical device is used for the hub node and the network configuration is simple, the equipment cost is low.

  Two types of optical devices used in the hub node are under consideration: star coupler (SC) and AWG. In the case of the configuration using SC, since packets arriving at the hub node are broadcast to all nodes, assuming that the number of multiplexed wavelengths is W and the transmission band of each wavelength channel is C, the maximum throughput that can be achieved in the entire network is at most. CW. Furthermore, access control is required due to the configuration in which the same wavelength channel is shared by a plurality of nodes. For this reason, the use efficiency of wavelength resources is low, and single-hop WDM networks using SC have been studied for LAN.

On the other hand, in AWG, wavelength resources can be spatially reused due to wavelength recursion (packets can be transferred between multiple nodes simultaneously using the same wavelength), and AWG is used as a hub node The throughput achievable in the entire network with respect to the number of multiplexed wavelengths W is CW ² , and since each node pair can exclusively use the wavelength channel, access control is also unnecessary. For this reason, a single-hop WDM network (hereinafter referred to as an AWG network) using AWG as a hub node has attracted attention as an all-optical network in MAN, which has strict cost requirements.

The AWG network is a star type composed of one hub node and N nodes. An N × N AWG is installed in each hub node, a transceiver and a wavelength multiplexing / demultiplexing device are installed in each node, and a node n ( n: n transceivers following any number of) consists of a transmitter _{T n} and the receiver _{R n.} Further, NF wavelengths are multiplexed on each optical core. However, F is FSR (Free Spectral Range), and is set to an integer value of 1 or more.

FIG. 2 is a configuration diagram showing an AWG network when N = 3 and F = 2.
As shown in FIG. 2, the wavelength channel fN + 1, fN + 2, fN + 3,... On the input port i of the AWG for any integer value f of f = 0, 1,. .., FN + N are led to output ports i, i + 1, i + 2,..., I−1, respectively, and wavelength channels fN + 1, fN + 2, fN + 3,. j, j-1, j-2, ... j + 1. As a result, logically independent F wavelength channels are installed between the nodes, and the F wavelength channels are used exclusively without competing with other packets between the ground. be able to.

In order to exchange packets between all nodes, it is important to install variable wavelength transceivers that can be adjusted to NF wavelengths or NF fixed wavelength transceivers that are set to different wavelengths. The use of multiple fixed wavelength transceivers is superior in reliability, stability, and technology maturity. Furthermore, when using variable-length transceivers, the sending node needs to adjust the receiving node's receiver to the working wavelength prior to each packet transfer, and each node can receive packets from only one wavelength channel at a time. Since this is not possible, throughput is reduced. Therefore, it is desirable that the AWG network has a transceiver configuration using NF fixed wavelength transceivers.
For the technologies described above, refer to the following Non-Patent Documents 1 to 4.

C. Fan, M.M. Reisslein, and S.R. Adams, “The FTA-FRA AWG Network: A Practical Single-Hop Metro WDM Network for Efficient Uni-and Multicasting,” IEEE Infocom 2004. M.M. Schutzow, M.M. Reisslein, and A.A. Worisz, “Wavelength Reuse for Efficient Packet-Switched Transport in an AWG-Based Metro WDM Network,” IEEE J. Lightwave Tech. Vol. 21, no. 6, pp. 1435-1454, 2003. N. P. Caponio, A.M. M.M. Hill, F.M. Neri, and R.M. Sabella, “Single-Layer Optical Platform Based on WDM / TDM Multiple Access for Large-Scale“ Switchless ”Networks,“ European Trans. Telecommun, Vol. 11, no. 1, pp. 73-82, 2000. K. Noguchi, Y .; Koike, H .; Tanabbe, K .; Hrada, and M.M. Matsuoka, “Field Trial of Full-Mesh WDM Network (AWG-STAR) in Metropolitan / Local Area,” IEEE J. et al. Lightwave Tech. , Vol. 22, no. 2, pp. 329-336, 2004.

In an AWG network using fixed wavelength transceivers, it is necessary to prepare NF transceivers in each node in order to enable packet transfer between all nodes. Therefore, since the total number of transceivers increases in proportion to N ² as N increases, there is a problem in scalability in the AWG network. For example, when about 200 MAN nodes are considered, the total number of transceivers is 40,000, which is not realistic as the number of transceivers installed in one MAN.

FIG. 3 is a configuration diagram of an AWG network that uses a coupler to reduce the AWG scale.
In order to reduce the total transceivers in the AWG network, it is effective to aggregate a plurality of nodes with couplers (CP) and then connect to the AWG as shown in FIG. Since the packet sent from the AWG is broadcast to the subordinate nodes by the splitter (SP), it reaches a node other than the target node. The node decodes the header of the received packet and discards packets other than those addressed to itself.
The M nodes are connected to one of the D CPs (SP) to be installed, but here, for convenience, the number of nodes accommodated in each CP (SP) is uniform, and M = N / D. Assume that the transmitter and receiver of the mth node belonging to CP (SP) d are denoted as T _dm and R _dm , respectively.

Since logically independent F wavelength channels are prepared between each CP and SP, each node can send a packet on any wavelength channel among the F wavelength channels corresponding to the SP to which the target node belongs. By sending the packet, it is possible to transfer the packet to an arbitrary node.
Therefore, DF is sufficient for the number of wavelengths multiplexed in each optical core and the number of fixed wavelength transceivers installed in each node, and the number of AWG ports can be suppressed to D. The number D of installed CP (SP) greatly affects the total number of transceivers and the load applied to each wavelength channel. However, the optimum design method for D has not been studied so far.

(the purpose)
An object of the present invention is to provide an AWG single-hop that can solve the scalability problem of an AWG network by deriving the optimal number of installed couplers that minimizes the total number of transceivers while satisfying a given delay constraint. It is to provide a WDM network configuration method, a program thereof, and a recording medium.

  In order to achieve the above object, the AWG single-hop WDM network configuration method of the present invention is as follows: (1) After a plurality of nodes are aggregated by couplers in an AWG single-hop WDM network targeting MAN using AWG as a hub node. In a network configured to connect to an AWG, a method for calculating the optimum number of installed couplers that minimizes the total number of required transceivers within a range that satisfies a given allowable packet transfer delay time from a given traffic amount. Features.

  Further, the present invention (2) in the AWG single-hop WDM network optimum configuration method (1), calculates the amount of traffic flowing on each wavelength channel carrying internal traffic from a given static AC traffic matrix, It is characterized in that a packet average transfer delay in each wavelength channel is derived, and from this, a minimum value of FSR for satisfying a given allowable average packet transfer delay and a maximum number of nodes that can be accommodated at that time are obtained.

  Further, the present invention (3) calculates the amount of traffic flowing on each wavelength channel carrying external traffic from a given static AC traffic matrix in the AWG single-hop WDM network optimum configuration method (1), The average packet transfer delay in each wavelength channel is derived, and from the given number of POP cores, the minimum value of FSR for satisfying the given allowable average packet transfer delay and the maximum number of nodes that can be accommodated at that time It is characterized by calculating | requiring.

  The present invention also provides: (4) the number of POP cores and the installation for satisfying the constraints on the two allowable maximum nodes obtained in the AWG single-hop WDM network optimum configuration method (2) (3). A combination of the number of couplers is obtained, and a value that minimizes the total number of transceivers is adopted as the optimum number of POP core wires and the number of installed couplers, respectively.

  Further, the present invention is also directed to (5) the AWG single-hop WDM network optimum configuration method (1), wherein a part of the internal traffic is multicast traffic and the internal traffic is determined from a given static AC traffic matrix. The amount of traffic flowing on each wavelength channel carrying the traffic is calculated, the packet average transfer delay in each wavelength channel is derived, and from this, the minimum value of FSR for satisfying the given allowable average packet transfer delay and at that time The maximum number of nodes that can be accommodated is obtained.

  The present invention also provides: (6) the number of POP cores and the number of installations for satisfying the constraints on the two allowable maximum nodes obtained in the AWG single-hop WDM network optimum configuration method (3) (5). A combination of the number of couplers is obtained, and a value that minimizes the total number of transceivers is adopted as the optimum number of POP core wires and the number of installed couplers.

  According to the present invention, the number of installed optical couplers is determined so as to minimize the total cost within a range satisfying the transfer delay of a given allowable packet, thereby greatly reducing the total number of transceivers particularly when the traffic amount is small. As compared with the AWG network, the total cost number can be reduced from 1/10 to 1/10.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system configuration diagram showing an embodiment of a large-scale AWG single-hop WDM network configuration method according to the present invention.
In FIG. 1, 100 is a packet transmission node s, 200 is a coupler m installed between the node and the AWG, 300 is an AWG (hub node), 400 is a splitter n installed between the AWG and the node, and 500 is a packet reception node. r.
The packet transmission node 100 (node s) includes a transceiver 101 and a wavelength multiplexing / demultiplexing device 102. The packet receiving node 500 (node r) includes a wavelength demultiplexing device 501 and a transceiver 502.

In the packet transmission node 100 (node s), a packet transmitted as an optical signal of each wavelength by the transceiver 101 is input to one optical core by the wavelength multiplexing / demultiplexing device 102.
The coupler 200 (coupler m) multiplexes packets transferred from all nodes connected to the coupler onto one optical core. The packet transmitted from the coupler 200 arrives at the AWG 300, but is output from the unique output port determined from the input port and wavelength of the AWG according to the wavelength circulation of the AWG, and arrives at the splitter 400 (splitter n). A packet arriving at the splitter 400 is broadcast to all nodes connected to the splitter, and a packet arriving at the packet receiving node 300 (node r) is multiplexed by the wavelength demultiplexer 501 and transmitted by the transceiver 502. Received.

Next, “network configuration” and “derivation of optimum number of couplers” will be described for the AWG single-hop WDM network optimum configuration method according to the embodiment of the present invention.
1) Network Configuration FIG. 4 is a network configuration diagram according to the embodiment of the present invention.
Internal traffic that is AC traffic inside the MAN and external traffic that is AC traffic between the outside of the MAN flow through the MAN. However, all external traffic passes to the WAN via POP (Point-Of-Presence) ( )) Spill (inflow). Therefore, since a large amount of traffic is concentrated on the POP, it is assumed that k optical cores are prepared between the POP and the hub node (AWG). Therefore, each node can transmit / receive a packet to / from the POP using k wavelength channels. Since D CPs (SPs) are installed, the number of AWG ports is D + k.

2) Derivation of the optimal number of couplers Since the number of AWG ports is D + k, in the network configuration of the present embodiment, the number of multiplexed wavelengths W is W = (D + k) F, and the total number of transceivers N _tr is N _tr = (N + k). ) (D + k) F. Therefore, CAPEX can be reduced as the number of installed CP (SP) D and the number of POP cores k are smaller. However, suppression of D increases the number of nodes M aggregated into one CP, and suppression of k decreases the number of wavelength channels that can be used for POP.
As a result, the load per wavelength channel increases and the packet transfer delay increases.

Therefore, in the present embodiment, for the given traffic amount, the optimum number of installed CP (SP) D and the number of POP cores that minimize N _tr in a range where the average packet transfer delay does not exceed the allowable value γ. k is derived. However, the number of nodes Md accommodated in CPd (SPd) is

とする。すなわち、Ｎ個のノードはＤ個のＣＰ（ＳＰ）に可能な限り均一に分散収容されるものと仮定する。そして、下記の値で示すＭｄの大きい方の値を＊Ｍと表記する。

And That is, it is assumed that N nodes are distributed and accommodated as uniformly as possible in D CPs (SPs). The larger value of Md indicated by the following value is expressed as * M.

＊Ｍ＝１のとき、ＡＷＧネットワークとなり、また、＊Ｍ＝ＮのときハブノードにＳＣを用いたＳＣシングルホップＷＤＭネットワークとなる。そのため、次の条件式の場合についてのみを考える。

* When M = 1, it becomes an AWG network, and when * M = N, it becomes an SC single-hop WDM network using SC as a hub node. Therefore, only the case of the following conditional expression is considered.

Considering static traffic, it is assumed that the ratio of internal traffic to the total traffic volume V is r (0 <r <1), and that all traffic exchanges are uniform. Each node sends a fixed length P packet in accordance with the Poisson process (the destination is a node other than its own node or POP). Let r _{1 be} the average retransmission wait time when packet transfer is successful.

  In the network configuration of the present embodiment, since the MAC is not performed in the CP, it is equivalent to the Aloha system. Therefore, the average packet transfer delay T on the wavelength channel of the CP in which M nodes are accommodated is calculated using the channel load G including the retransmission and the round trip time R.

と表される。ただし、収容ユーザ数が有限数Ｍの場合について考慮している。Ｔ≦γを満たすためには、Ｇの許容最大値をＧ_ｍａｘとすると、

It is expressed. However, the case where the number of accommodated users is a finite number M is considered. In order to satisfy T ≦ γ, when the maximum allowable value of G is G _max ,

となる。

It becomes.

  On the other hand, the channel throughput S is

となり、

And

First, consider the case where all traffic is unicast. The internal volume of traffic flowing from any node i to any node j other than i When d _I,

となる。

It becomes.

Since the maximum value of the number of nodes accommodated in one CP (SP) is * M, the amount of internal traffic that flows on a wavelength channel installed between any CP and SP (not including retransmission) The maximum value v _I is

となる。

It becomes.

For wavelength channels carrying internal traffic, it is necessary to satisfy v _I ≦ CP _max . Therefore, from the equations [Equation 4] and [Equation 6], the first constraint equation of * M _I

を得る。ただし、

Get. However,

である。

It is.

Meanwhile, POP from any node i, or the external traffic amount flowing through the node i from POP When _{d E,}

となる。任意のＣＰからＰＯＰ、もしくはＰＯＰから任意のＳＰに対して設置される波長チャネル上に流れる最大トラヒック量をｖ_Ｅとすると、

It becomes. Assuming that v _E is the maximum amount of traffic that flows on a wavelength channel installed from any CP to POP, or from POP to any SP,

となる。ＰＯＰからＳＰ方向に流れる外部トラヒックはＣＰを経由しないため、ＣＰからＰＯＰ方向に流れる外部トラヒックについてのみ、ｖ_Ｅ≦ｋＣＳ_ｍａｘを満たすことを考えればよい。従って、式〔数４〕，式〔数１０〕より、＊Ｍの第二の制約式、

It becomes. Since the external traffic flowing from the POP to the SP direction does not pass through the CP, it is only necessary to consider that v _E ≦ kCS _max is satisfied only for the external traffic flowing from the CP to the POP direction. Therefore, from the equations [Equation 4] and [Equation 10], the second constraint equation of * M,

を得る。ただし、

Get. However,

である。

It is.

  Since F needs to satisfy * M (F) ≧ 2, from the formula [Equation 8], the minimum value that F can take,

が得られる。一方、式〔数１２〕より＊Ｍ_Ｅ（Ｆ_０，ｋ）≧２をｋに対して解くことにより、ＰＯＰ心線数ｋの取り得る最小値ｋ_αが、

Is obtained. On the other hand, by solving * M _E (F ₀ , k) ≧ 2 for k from the equation [Equation 12], the minimum value k _α that the number of POP cores k can take is

と得られる。Ｆ＝Ｆ_０としたときの＊Ｍ_Ｉ（Ｆ）と＊Ｍ_Ｅ（Ｆ，ｋ）の値を便宜上、＊Ｍ_Ｉ、＊Ｍ_Ｅ（ｋ）と表記する。式〔数７〕，式〔数１１〕より、遅延制約γを満足するために＊Ｍが取り得る上限値＊Ｍ（ｋ）はｋに依存する。＊Ｍ_Ｉはｋに対して不変であり、一方、＊Ｍ_Ｅ（ｋ）はｋの増加に対して単調に増加することから、ｋ_βを＊Ｍ_Ｅ（ｋ）≧＊Ｍ_Ｉを満たすｋの最小値と定義すると、

And obtained. For convenience, the values of * M _I (F) and * M _E (F, k) when F = F ₀ are expressed as * M _I and * M _E (k). From the equations [Equation 7] and [Equation 11], the upper limit value * M (k) that * M can take to satisfy the delay constraint γ depends on k. * _{M I} is invariant to k, whereas, _{* M} E (k) meet the increasing monotonically with increasing k, a k _beta a _{* M E (k) ≧ *} M I k Is defined as the minimum value of

を閾値として、＊Ｍ（ｋ）は、

Is the threshold, * M (k) is

となる。

It becomes.

Even if k is increased beyond k _β , the upper limit for * M does not change, so k should be set in the range of k _α ≦ k ≦ k _β . For the obtained * M allowable maximum value * M (k), the optimal value (allowable minimum value) * D (k) of the number of CP (SP) is

より得られる。ｋ_α≦ｋ≦ｋ_βの範囲で全ての整数値ｋについて総トランシーバ数Ｎ_ｔｒ＝（Ｎ＋ｋ）｛＊Ｄ（ｋ）＋ｋ｝を計算し、この値が最小となるｋと＊Ｄ（ｋ）の値を、各々最適なｋとＤの値として採用する。

More obtained. Calculate the total number of transceivers N _tr = (N + k) {* D (k) + k} for all integer values k in the range of k _α ≦ k ≦ k _β , and k and * D (k) at which this value is the minimum Are adopted as optimum values of k and D, respectively.

  Next, the optimum values of D and k are derived for a case where a part of the traffic is multicast traffic. Here, it is assumed that all external traffic is unicast packets. On the other hand, it is assumed that packets of internal traffic generated according to the Poisson process at each node are unicast packets with probability μ and multicast packets with probability 1-u. If it is a multicast packet, g packets are randomly selected from N-1 nodes other than the originating node, and set as receiving nodes. The multicast size g is also selected randomly in the range of 2 to G (2 ≦ G ≦ N−1). When sending a multicast packet, the receiving node belonging to the same SP is broadcast by the SP, so there is no need to generate a copy packet. Therefore, when the receiving node is accommodated in g SPs, the transmitting node generates g copy packets and transmits them on the corresponding g wavelength channels.

When packet blocking occurs in the CP, the packet is retransmitted only on the corresponding wavelength channel.
Note that the maximum number of nodes that can be accommodated in the CP (SP) is * M _{I. When} a node generates a packet of internal traffic, the packet is transmitted on a certain wavelength channel installed in this CP. If the maximum value of the probability is σ (* M),

となる。

It becomes.

The maximum value v _{I of the} amount of internal traffic flowing (not including retransmission) on the wavelength channel installed between any CP and SP is expressed by using σ (* M),

より得られる。全ての内部トラヒックがユニキャストである場合（ｕ＝１）、上式は式〔数６〕に一致する。
ｖ_Ｉ≦ＣＳ_ｍａｘより、＊Ｍは制約式、

More obtained. When all the internal traffic is unicast (u = 1), the above equation agrees with Equation [6].
From v _I ≦ CS _max , * M is a constraint equation,

を満たす必要がある。＊Ｍ≧２で式〔数２０〕が満たされる＊Ｍの解が存在するためには、＊Ｍ＝２を代入し、Ｆの取り得る最小値Ｆ_０を次のように得る。

It is necessary to satisfy. In order for * M ≧ 2 to satisfy the formula [Equation 20], * M = 2 is substituted, and the minimum value F ₀ that F can take is obtained as follows.

  Although it is difficult to solve the equation [Equation 20] explicitly, * M is

の範囲の整数値をとることから、この範囲で式〔数２０〕でＦ＝Ｆ_０とした制約式を満足する最大の＊Ｍを数値的に得ることができる。得られた＊Ｍの解を＊Ｍ_Ｉとすれば、外部トラヒックを運ぶ波長チャネルについては、式〔数１０〕がそのまま使用できるので、トラヒックが全てユニキャストである場合と同様にｋとＤの最適値を導出することができる。

In this range, the maximum * M that satisfies the constraint equation of F = F ₀ in the equation [Equation 20] can be obtained numerically. If the obtained * M solution is * M _I , the equation [10] can be used as it is for the wavelength channel carrying external traffic, so that k and D are all the same as in the case where the traffic is all unicast. An optimal value can be derived.

(Evaluation conditions)
Next, numerical evaluation results of the present invention will be described.
C = 10 Gbps, P = 1500 bytes, and N = 100, r = 0.5, and γ = 1.0 × 10 ⁻³ seconds unless otherwise specified. Further, the round trip time between end terminals where retransmission control is performed is set to a constant value R = 1.0 × 10 ⁻⁴ seconds (distance between end terminals 10 km), and the backoff time during retransmission is an average of 10 packets of random time. Assuming that, τ ₁ = R + τ = 1.010 × 10 ⁻⁴ seconds and τ ₂ = 10τ = 1.2 × 10 ⁻⁵ seconds. However, τ is the packet time τ = P / C = 1.2 × 10 ⁻⁶ seconds.

  In addition to the present invention (Proposed Network: hereinafter abbreviated as P-NW), a normal AWG network (AWG-NW) shown in FIG. 2 in which all nodes are directly accommodated in a hub node (AWG) is used for comparison. . However, also in the AWG network, k cores are installed between the POP and the AWG in consideration of the POP that handles external traffic as shown in FIG. In the AWG network, node aggregation by couplers is not performed, so the design of the number of couplers D is unnecessary, but the design of the FSR value F and the number of POP cores k is necessary. First, consider the case where all traffic is unicast.

In the AWG network, wavelength paths are exclusively prepared between each pair of nodes. Therefore, for simplicity, the design is performed so that the traffic demand applied to each wavelength channel is simply equal to or less than the wavelength band. As the amount of traffic approaches the line capacity, the delay time increases to infinity. Therefore, in actuality, the design should be performed with a margin added, but here, the lower limit value of the AWG network capacity is derived and compared. Used for. For wavelength channels that carry internal traffic, it is only necessary to satisfy d _I / F ≦ C.

を得る。

Get.

On the other hand, for wavelength channels carrying external traffic, it is only necessary to satisfy d _I / F ₀ ≦ kC. Therefore, k can satisfy k ≧ {(1−r) V} / 2CNF ₀ from Equation [9]. . Therefore,

と設定する。内部トラヒックの一部がマルチキャストである場合、内部トラヒックを運ぶ波長チャネル上の最大トラヒック量は、式〔数１９〕に＊Ｍ＝１を代入することにより得られることから、Ｆの取り得る最小値は、

And set. When a part of the internal traffic is multicast, the maximum amount of traffic on the wavelength channel carrying the internal traffic can be obtained by substituting * M = 1 into the equation [Equation 19]. Is

となる。ＰＯＰ心線数ｋについては、やはり式〔数２３〕を用いて設定できる。

It becomes. The POP core number k can also be set using the formula [Equation 23].

(When traffic is all unicast)
In the following, the case where all traffic is unicast will be evaluated.
5 and 6 are characteristic diagrams showing the total number of transceivers when the average packet transfer delay allowable value γ and the internal traffic amount ratio r are set. FIG. 5 is a diagram showing the total number of transceivers N _tr when the average packet transfer delay allowable value γ = 1.0 × 10 ⁻³ seconds and the internal traffic amount ratio r = 0.2 and 0.8. 6, the total transceiver when the average packet transfer delay allowable value γ = 2.0 × 10 ⁻⁴ seconds and 1.0 × 10 ⁻³ seconds and the internal traffic amount ratio r = 0.5 is assumed. It is a figure which shows number N _tr .

As shown in FIGS. 5 and 6, the FSR value was F ₀ = 2 only for P-NW when r = 0.8 and V = 1.15 × 10 ¹³ bps, but all other points F ₀ = 1. P-NW is N _tr = (N + k) (D + k) F. However, since external traffic is not aggregated by CP, N _tr increases as the ratio of the amount of external traffic increases (r decreases).
Further, N _tr increases as the allowable delay time γ is smaller because the load per wavelength channel needs to be suppressed. AWG-NW is N _tr = (N + k) ² F, and is determined by the number of nodes N and the number of POP cores k. The required k value increases as the total traffic amount V increases, but in the evaluated V range, 1 ≦ k ≦ 5 when r = 0.2, and 1 ≦ k ≦ 2 when r = 8, Both are smaller than N = 100. Therefore, N is dominant, and regardless of V, approximately N ² = 10000 transceivers are required. On the other hand, the P-NW can appropriately set the number of CPs (SP) according to V, and can greatly reduce N _tr . In particular, when V is small, the delay constraint can be satisfied even if a large number of nodes are aggregated into the CP, so that D can be made smaller and the effect of reducing N _tr is great.

Finally, compare the total network cost. Since the transmission distance is short on the network scale in the metro area, the cost related to transmission of optical cores, optical amplifiers and the like can be ignored compared to the cost of the node. Therefore, only the transceiver and the wavelength multiplexing / demultiplexing device are considered as cost components of the AWG-NW. P-NW requires CP and SP in addition to these. However, the necessary number of CPs and SPs is D, which is smaller than the necessary number of other devices, and the cost of these devices is small, so it is not considered. Let C _{tr be} the relative cost of the transceiver, and C _{dm be} the relative cost of the wavelength demultiplexing device per wavelength. Considering the current price, C _tr = 10 and C _dm = 1 are set.

7, 8 and 9 are characteristic diagrams showing the total network cost when the number of nodes is determined.
Here, the total network cost is shown when N = 50, 100, and 200, respectively. Only P-NW at N = 50 shows a change in FSR value in the range of the evaluated total traffic volume V. When V ≦ 3.8 Tbps, F ₀ = 1, and when 4.6 ≦ V ≦ 8.0 Tbps F ₀ = 2 and when V ≧ 9.5 Tbps, F ₀ = 3, and the total cost increased rapidly at the point where the FSR value increased. At all other points, F ₀ = 1.

P-NW has a greater cost reduction effect when V is smaller than AWG-NW. As V increases, D increases, and the reduction effect such as the number of transceivers becomes small, so the cost reduction effect also decreases. Also, as the number of nodes N increases, the total network cost of the P-NW does not increase so much, whereas the total network cost of the AWG-NW increases greatly.
Accordingly, since the cost reduction effect of the P-NW increases as N increases, node aggregation by the coupler is more advantageous for a large-scale MAN.

(When part of the traffic is multicast)
10 is a relationship characteristic diagram of the total number of transceivers with respect to the total traffic amount V, FIG. 11 is also a relationship characteristic diagram of the required FSR value F ₀ with respect to V, and FIG. 12 is also a relationship characteristic diagram of the total network cost with respect to V. It is.
In the previous section, we evaluated the case where all the traffic is unicast, but in this section we evaluate the case where a part of the internal traffic is multicast. In this section, N = 100, r = 0.5, and γ = 1.0 × 10 ⁻³ seconds.
FIG. 10 shows the relationship between the total number of transceivers N _{tr and} the total traffic amount V when the maximum multicast size is G = 50 and the unicast ratio of internal traffic is u = 0.2 and 0.5. Yes.

FIG. 11 shows the relationship of the required FSR value F _{0 with} respect to the total traffic V when the maximum multicast size is G = 50 and the internal traffic unicast ratio u = 0.2 and 0.5. ing. The smaller u is, the more multicast traffic increases and the actual network load increases, so both characteristics increase. In particular, in the P-NW, packet collisions at the CP rapidly increase with an increase in load, so that the FSR value required to increase the number of installed CP (SP) D to 2 or more greatly increases. As a result, N _tr The degree of increase is also large.

Finally, FIG. 12 shows a relationship diagram of the total network cost with respect to the total traffic V when u = 0.5 and G = 50.
Compared to the case where all traffic is unicast (FIG. 8), the total network cost of the P-NW is increased, but even when multicast traffic is mixed, in the region where V is less than several Tbps, The cost advantage of the invention was confirmed.

The embodiment of the present invention described above is realized by a general-purpose or dedicated computer. That is, the procedure of the network configuration method is programmed, and this program is executed by the computer, thereby starting up the computing unit of the computer, calculating each arithmetic expression, and configuring the target network.
Also, if the AWG single-hop WDM network configuration method described in this embodiment is programmed and the completed program is stored in a recording medium such as a CD-ROM, the recording medium is mounted on the computer, and the computer is loaded with the recording medium. The present invention can be easily realized by installing and executing the program. It is also possible to generalize the program of the present invention by downloading the program to another computer via a network.

It is a block diagram inside the system of the network which concerns on one Embodiment of this invention. It is a block diagram of the conventional AWG network. It is a block diagram of the AWG network system which aimed at reduction of the AWG scale using the coupler. 1 is an overall connection diagram of a network according to an embodiment of the present invention. It is a characteristic view (1) of the total number of transceivers with respect to the total traffic amount. It is a characteristic figure (2) of the total number of transceivers with respect to the total traffic amount. It is a characteristic view (1) of the total cost ratio with respect to a total traffic amount. It is a characteristic view (2) of the total cost ratio with respect to a total traffic amount. FIG. 6 is a characteristic diagram (3) of a total cost ratio with respect to a total traffic amount. It is a characteristic figure of the total number of transceivers with respect to the total traffic amount. It is a characteristic view of the FSR value with respect to the total traffic amount. It is a characteristic view of the total cost ratio with respect to the total traffic amount.

Explanation of symbols

100: Nodes
101: Transceiver 102: Wavelength demultiplexing device 200: Coupler m
300: AWG
400: Splitter n
500: Node r
501: Wavelength multiplexer 502: Transceiver T ₁₁ through T _DM: Transmitter R ₁₁ to R _DM: Receiver CP1～CPD: Coupler SP1～SPD: Splitter

Claims (8)

In a network configuration method of a configuration in which a plurality of nodes are aggregated by a coupler in an AWG single-hop WDM network targeted for a MAN using an AWG as a hub node, and then connected to the AWG.
By starting the computing unit of the computer, the traffic amount written in the memory in advance and the allowable packet transfer delay time written in the memory are read, and within the range satisfying the allowable packet transfer delay time, from the traffic amount An AWG single-hop WDM network configuration method, characterized in that the number of installed couplers that minimizes the total number of required transceivers is calculated by the following equation.

(Where D (k) is the minimum allowable number of CP (SP), * M is the maximum number of nodes accommodated in one CP (SP), and N is the number of nodes) The AWG single-hop WDM network configuration method according to claim 1,
Reading out the static AC traffic matrix pre-written in the memory, and calculating the traffic amount flowing on each wavelength channel carrying internal traffic from the AC traffic matrix by the following equation:
Deriving the average packet transfer delay time in each wavelength channel,
An AWG single-hop WDM network configuration method characterized in that the minimum value of FSR for satisfying a given allowable average packet transfer delay and the maximum number of nodes that can be accommodated at that time are calculated.

(Where v ₁ is the maximum internal traffic volume, F is FSR, d _I is the internal traffic volume, r is the internal traffic volume ratio, and V is the total traffic volume)

(Where T is the average packet transfer delay time, τ ₁ is the average transfer delay time when the packet transfer is successful, τ ₂ is the average retransmission wait time, G is the channel load including retransmission, R is the round trip time, and M is the capacity. Number of users)

(However, F0 is the minimum value of FSR, and γ is a delay constraint.) The AWG single-hop WDM network configuration method according to claim 1,
A static AC traffic matrix pre-written in the memory is read, and the amount of traffic flowing on each wavelength channel carrying external traffic from the AC traffic matrix is calculated by the following equation:
Calculate the packet average transfer delay time in each wavelength channel,
Then, from the given number of POP cores, the maximum number of nodes that can be accommodated to satisfy the given allowable average packet transfer delay is calculated.

(Where d _E is the amount of external traffic flowing from any node to POP or from POP to node, and r is the ratio of internal traffic to the total traffic amount V)

In the AWG single hop WDM network configuration method according to claim 2 or 3,
Calculate the set of the number of installed POP cores and the number of installed couplers for satisfying the constraints on the two maximum accommodated nodes obtained above by the following equation:
A method for configuring an AWG single-hop WDM network, wherein a value that minimizes the total number of transceivers is adopted as the number of POP cores and the number of installed couplers, respectively.

(Where σ (* M) is the maximum value of the packet transmission probability, v _I is the maximum value of the internal traffic flowing on the wavelength channel, γ is the allowable value of the average packet transfer delay, and r is the internal of the total traffic V Traffic occupation ratio, G and ε (see [Equation 7]) The AWG single-hop WDM network configuration method according to claim 1,
The static AC traffic matrix pre-written in the memory is read, and the traffic flowing on each wavelength channel carrying the internal traffic from the static AC traffic matrix is targeted for the case where a part of the internal traffic is multicast traffic. Calculate the amount by the following formula,
Calculate the packet average transfer delay time in each wavelength channel,
An AWG single-hop WDM network configuration method, comprising: calculating a minimum value of FSR for satisfying a given allowable average packet transfer delay and a maximum number of nodes that can be accommodated at that time.

The AWG single-hop WDM network configuration method according to claim 3 or 5,
Calculate the set of the number of POP cores and the number of installed couplers for satisfying the constraint on the two maximum accommodated nodes obtained above,
A method for configuring an AWG single-hop WDM network, wherein a value that minimizes the total number of transceivers is adopted as the number of POP cores and the number of installed couplers, respectively.   An AWG single-hop WDM network configuration program for causing a computer to execute the procedure of the AWG single-hop WDM network configuration method according to claim 1.   A computer-readable recording medium on which the AWG single-hop WDM network configuration program according to claim 7 is recorded.

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