JP2003258886A - Method for establishing optical path - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dynamically establish an optimal optical path corresponding to the housing request of a packet traffic in the multilevel network of a packet network and an optical network. <P>SOLUTION: Housing of a specific inter-ground packet traffic is performed by searching a minimum optical path link cost route as seen from the packet network. The optical path is established first when the packet traffic cannot arrive at a goal through a conventional optical path. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention realizes cooperative operation of a large-capacity optical path network realized by an optical cross-connect device and a service network realized by a Layer2 / 3 switch such as an IP router. For the new optical path installation method necessary for

[0002]

2. Description of the Related Art Due to an increase in data communication traffic such as the Internet, the introduction of node devices having a throughput of Tbit / s at present and 10-100 Tbit / s or more in the near future is being promoted. As means for realizing a node device having such a large-scale transfer capability, a packet switch (P that processes TCP / IP packets, which is a mainstream communication protocol on the Internet, is used.
SC: Packet Switch Capable) and optical switch for routing optical paths (LSC: Lambda Switch Capable)
photonic router that works together [reference:
k.Shimano, A.Imaoka, Y.Takigawa, and K.-l.Sato,
in Technical Digest of NFOEC'2001, Vol.1 p. 5, Ju
ly.2001.] is influential. By using this photonic router, a conventional IP network composed of a packet switch (PSC) and an optical switch (LS) can be used.
A large-capacity optical path network (hereinafter referred to as an optical network) composed of C) can be more closely linked.

[0003]

However, when the above-mentioned IP network and optical network are operated in cooperation with such a node device, a method of newly establishing an autonomous optical path is effective in effectively utilizing network resources. It will be an important point. However, research on the construction of networks in which lower networks (IP networks) and upper networks (optical networks) both operate dynamically and autonomously in a decentralized manner and cooperate with each other has recently begun. However, a method of dynamically establishing a new optical path following the fluctuation of packet traffic has not been put to practical use.

The present invention solves the above-mentioned problems, enables a new optical path to be installed in response to a packet traffic accommodation request, and enables an optimum new optical path to be installed according to the load condition of the network. The purpose is to do.

[0005]

In order to solve the above-mentioned problems, the first invention comprises a packet network composed of an optical path link and a packet switch, and a fiber link accommodating the packet network and an optical switch. In an optical network that accommodates specific point-to-point packet traffic, the shortest route seen from the packet network, that is, the minimum optical path link cost route is searched, and the new optical path is established by using the existing optical path for the packet traffic. The feature is that it is performed only when it is impossible to reach the destination.

In the second invention, in the first invention, the new optical path is established when the accommodated packet traffic cannot reach the destination by the existing optical path within the specified number of hops. Is characterized by.

In a third invention, in a packet network composed of an optical path link and a packet switch, and in an optical network accommodating the packet network and composed of a fiber link and an optical switch, accommodation of specific point-to-point packet traffic is not possible. , The shortest route seen from the optical network, that is, the minimum fiber link cost route is searched, and the new optical path is installed when the traffic cannot reach the destination by the existing optical path on the route. It is characterized by doing it for the first time.

In a fourth aspect of the present invention, in the third aspect, the new optical path is installed when the accommodated packet traffic cannot reach the destination by the existing optical path within the specified number of hops. Is characterized by.

According to a fifth aspect of the present invention, in a packet network composed of an optical path link and a packet switch, and in an optical network accommodating the packet network and composed of a fiber link and an optical switch, a new optical path is installed at a specific ground. The feature is that new optical paths are installed on the shortest path seen from the optical network, that is, the path with the lowest fiber link cost.

[0010]

FIG. 1 shows an example of the configuration of a network system according to an embodiment of the present invention. This embodiment is composed of a packet network 7 composed of an optical path link composed of a packet switch 2 and an optical path 4 (4 ′), and an optical network 8 composed of a fiber link composed of an optical switch 3 and a fiber 5. Multi-layered network is assumed. The packet network 7 is
It is a packet cell switch network and, in the case of the Internet, an IP network. 4 in the figure is an optical path (link) of a path through which a signal actually flows,
Reference numeral 4'denotes an optical path link viewed from the packet network. 6 represents traffic.

Such a multi-layer network can be constructed by the photonic routers 1 (1-1 to 1-4) in which the packet switch 2 and the optical switch 3 are integrally mounted.

As shown in FIG. 2, the photonic router 1 is composed of a packet switch 2 and an optical switch 3, and an integrated control device (GMPLS controller) 10 for integrally managing these. Control signals are exchanged between the integrated control devices 10 of each photonic router 1 through a control signal line.

As the optical switch 3, a 128 × 128 switch is used, and it has an ability to input / output four fiber links in which optical paths are multiplexed by 32 wavelengths. The transmission speed of each optical path is 2.5 Gbit / s, and SONET O
Terminated on the C-48 interface.

The control signal line is composed of a SONET OC-3 line having a transmission speed of 155 Mbit / s, and the control signal propagating through the control signal line is, for example, OSPF / for acquiring the network topology of the photonic router network. RSVP-TE / CR-LDP protocol that sets / cancels an optical path set between IS-IS protocol packets and packet switches,
LMP (Link Manag) that monitors the failure of each fiber link
ement Protocol) packet.

Therefore, the integrated control device 10 of each photonic router 1 is equipped with a functional unit that processes these control signal protocols, and the routing processing functional unit (O
SPF / IS-IS protocol processing function) 20, optical path setting management function unit (RSVP-TE / CR-LDP protocol processing function) 30, optical fiber and link failure management function unit (LMP protocol processing function) 40 of adjacent nodes 40
It is composed of.

The routing processing function unit 20 includes a flooding unit 21 and a link state database (DB) 22.
An extended link status database (DB) 23, a switching capability monitoring unit 24, a route calculation unit 25, and a next hop database (DB) 26.

The flooding unit 21 is a functional unit for notifying adjacent nodes of the link status information collected from the own node and other nodes. The link status DB 22 and the extended link status DB 23 are databases that hold link information collected from other nodes, and the link status DB 2
2 stores optical path link status information, and the extended link status DB 23 stores fiber link status information.

Here, the optical path link status information stored in the link status DB 22 is, specifically, vacant information and cost information of the optical path link which connects two packet switches and is accommodated in the fiber link. is there. Also,
The fiber link status information stored in the extended link status DB 23 is, specifically, free information and cost information of a fiber link that connects two optical switches.

Switching capability monitoring unit 24
Is a functional unit that monitors the switch status of its own node.
For example, not only the function of setting the optical path to the optical switch 3 in the switch of the own node, but also the optical path to the packet switch 2
If there is a capacity to be accommodated in, the other nodes are advertised that the switching capability of the packet switch / optical switch exists.

The route calculation unit 25 calculates a transfer route of an optical path (OLSP) set from the link state DB 22 and a logical path (LSP) switched by the packet switch 2 or a packet.

The next hop DB 26 is a database in which the result of route calculation is stored, and stores information as to which interface a packet should be transferred to reach each node.

The optical path setting management function section 30 has a path database (DB) 31 in which optical path information is stored and a path setting deletion function section 32 for setting / deleting an optical path. The link failure management function unit 40 also monitors the link / adjacent node status database (DB) 41 having the status information of the optical fiber and the adjacent node and the advertisement information from other nodes to detect the link failure. It has a signal processing function unit 42.

The above-mentioned routing processing function unit 20 defines the link cost for each layer network. That is, the routing processing function unit 20 defines the cost of the fiber link connecting the two optical switches and the cost of the optical path link connecting the two packet switches and accommodated in the fiber link. With these costs, the cost of the optical path accommodated in the fiber link and the transfer cost of the packet traffic accommodated in the optical path link are calculated by the Dijkstra algorithm, and the packet traffic is calculated between the start point and the end point of the traffic. Transfer processing is performed on a route that minimizes the total cost, and the optical path is set on the route that minimizes the cost between the set start point-end point sections.

Here, the cost of the fiber link is assigned using a value such as the distance of each fiber section, the reciprocal of the capacity of the fiber link (reciprocal of the number of optical paths that can be accommodated), or the cost required for actual construction. To be On the other hand,
The cost of the optical path link set between the two packet switches is assigned using the reciprocal of the transmission rate of each optical path or the sum of the cost of the fiber links accommodating the optical path and a value obtained by multiplying a certain constant. As described above, the costs of the fiber link and the optical path link on the same route are generally defined by different values.

[Embodiment 1] In the present embodiment, FIG.
When a request for accommodating specific point-to-point packet traffic occurs in the network as shown in (1), the shortest path (minimum optical path link cost path) seen from the packet network 7 is searched first. If it is possible to reach the destination with the existing optical path, the packet traffic is accommodated on that route, and if it is not possible, a new optical path is installed.

FIG. 3 is a diagram for explaining the first embodiment, and FIG. 4 is a flow chart for the first embodiment.

In FIG. 3, each photonic router 1-
1 to 1-5 will be described as Node # 1 to Node # 5. The same applies to other embodiments described later. OLSP #
1 is an optical path connecting Node # 1 and Node # 4, O
LSP # 2 is an optical path connecting Node # 4 and Node # 5, OLSP # 3 is an optical path connecting Node # 5 and Node # 3, and OLSP # 4 is Node # 1 and Nod.
The optical path connecting with e # 2, OLSP # 5, is Node # 1
And Node # 3.

The cost of the optical path link is OLSP # 1.
For OLSP # 4, "10", OLSP respectively
It is “40” for # 5.

The cost of the fiber link is Nod.
Between e # 1 and Node # 2, Node # 2 and Node # 3
, Node # 1 and Node # 4, Node # 4 and N
There are "50" between the node # 5 and Node # 5.
And "Node # 3" are "20".

For example, if a packet traffic accommodation request occurs between Node # 1 and Node # 3, the route that minimizes the optical path link cost of the existing optical path connecting Node # 1 and Node # 3. Is searched (step S11). End point node (Node)
If there is no route to # 3), that is, if the cost to the end point node is infinite, the process proceeds to step S14.
If there is a route, the packet traffic is accommodated in the optical path of the searched route and the packet is transferred (step S
13).

If there is no optical path reaching Node # 3, Node # 1 and Nod including the fiber link are also included.
A route with the lowest cost up to e # 3 is searched (step S14). If the route is found (step S1)
5), an optical path is newly established on the route, packet traffic is accommodated in the newly established optical path, and the packet is transferred (step S16). Even if the fiber link is included, if there is no route to the end point node (Node # 3), that is, if the cost to the end point node is infinite, packet transfer is blocked or the packet is discarded (step S17).

By the processing shown in FIG. 4 above, in the example of FIG. 3, packet traffic is accommodated in the priority order shown in the figure. That is, as the optical path link from Node # 1 to Node # 3, Node # 1- # 4- # 5-
There is a route of # 3 and a route of Node # 1- # 3 (via # 2), and the former optical path link cost is "30" (O
LSP # 1, # 2, # 3 cost), and the latter optical path link cost is “40” (OLSP # 5 cost), so it is ranked 1 (Node # 1- # 4- # 5). −
# 3) and the order 2 (Routes of Node # 1 to # 3 (via # 2)) are stored in the optical path in the order, and the optical path will be released when the available capacity of these optical paths is insufficient. Newly established.

When a new optical path is installed, the following two cases can be set. Case (a): An optical path is newly established in a section where the packet traffic to be accommodated matches the ground. Case (b): An optical path is newly installed in a section where the cost of the newly installed optical path is minimized, and packet traffic is accommodated in the route using the optical path.

In the case of FIG. 3 (a), the Case
(A): shows the case of Node # 1- # 3 (#
A new optical path will be installed on the route (via 2).

On the other hand, in the case of FIG.
In the case of e (b) :, an optical path is newly established between Nodes # 2 and # 3, and packet traffic is accommodated in the route using the optical path. That is, Node #
It becomes the route of 1- # 2- # 3.

By this method, it is possible to newly set up a dynamic optical path in response to a packet traffic accommodation request. On the other hand, even if there is not sufficient traffic between specific destinations, the optical path is autonomous between the relevant destinations. It is possible to prevent the new installation and reduce the fiber link and optical switch capacity required for the entire network.

[Second Embodiment] FIG. 5 is a diagram for explaining the second embodiment, and FIG. 6 is a flow chart of the second embodiment.

In the second embodiment, the route search is performed in consideration of the limitation on the number of OLSP hops. Here, when a request for accommodating specific point-to-point packet traffic occurs, first, the shortest route (minimum optical path link cost route) viewed from the packet network 7 is searched. If it is possible to reach the destination by the existing optical path with the number of hops within the specified number, the packet traffic is accommodated on that path, and if it is not possible, a new optical path is installed.

In the example of FIG. 5, as in the first embodiment, N
The minimum optical path link cost route from node # 1 to Node # 3 is searched, but Node # 1- # 4- # 5- # 3
Since the number of OLSP hops exceeds the specified number,
Accommodating packet traffic is “prohibited” and Nod
The routes of e # 1- # 3 (via # 2) are ranked first. Packet traffic is accommodated in the optical path of the route of the first rank, and the optical path is newly established when the free capacity of this optical path is insufficient.

The flow chart of the second embodiment (steps S21 to S27) shown in FIG. 6 is almost the same as the flow chart of the first embodiment (steps S11 to S17) shown in FIG. 4, but steps S22 and S25 are performed. In determining the result of the route search, the search route is OLS.
The first embodiment deals with the point that it is impossible to reach the destination by the existing optical path when the number of P hops is exceeded.
Different from

In the second embodiment, the number of relay optical paths (that is, the relay packet switch nodes) can be suppressed as compared with the first embodiment, and the transfer processing load of the packet switch nodes can be reduced. Become.

When a new optical path is newly installed, the following two cases can be set as in the cases (a) and (b) shown in FIG. Case (a): An optical path is newly established in a section where the packet traffic to be accommodated matches the ground. Case (b): An optical path is newly established and used in a section in which the cost of the newly-established optical path is minimized within a range satisfying the specified number of relay optical paths (that is, relay packet switch nodes). Include packet traffic in the route.

[Third Embodiment] FIG. 7 is a diagram for explaining the third embodiment, and FIG. 8 is a flowchart of the third embodiment.

In the third embodiment, when a request for accommodating specific point-to-point packet traffic occurs, first, the shortest route seen from the optical network 8 (minimum fiber link cost route).
To explore. This is different from the first embodiment in which the shortest route (minimum optical path link cost route) viewed from the packet network 7 is searched. An optical path will be newly installed only when the destination cannot be reached by the existing optical path on this route.

Description will be given according to the flow chart shown in FIG. For example, if a packet traffic accommodation request is issued between Node # 1 and Node # 3, Nod
A route that minimizes the fiber link cost of the existing optical path connecting e # 1 and Node # 3 is searched (step S).
31). End point node (Node # 3) with existing fiber
If there is no route up to, that is, if the fiber link cost to the end node is infinite, step S36
Go to.

If there is a route, it is judged whether or not there is an existing optical path corresponding to the searched route (step S3).
3) If there is an optical path, the packet traffic is accommodated in the optical path and the packet is transferred by the search route (step S34). If there is no existing optical path corresponding to the search route, an optical path is newly established in the short section of the optical path, the packet traffic is accommodated in the optical path, and the packet is transferred (step S35).

If there is no fiber link that can reach the end node, the route is searched including the existing optical path link (step S36). As a result, if it is impossible to reach the end point node (step S37), the process proceeds to step S39. If there is a route that can reach the end point node, the packet is transferred by the search route (step S
38). At this time, if there is an optical path shortage section on the search route, an optical path is newly established in that section. If the end point cannot be reached by any route, the packet transfer is blocked or the packet is discarded (step S39).

By the above processing shown in FIG. 8, packet traffic is accommodated in the priority order shown in FIG.

In the third embodiment, the first and second embodiments are used.
Compared with the above, the route (route) accommodating the packet traffic matches the route with the minimum fiber ring cost, so that it is possible to reduce the waste of the optical network resource.

When a new optical path is installed, the following two cases can be set as in the cases (a) and (b) shown in FIG. Case (a): An optical path is newly established in a section where the packet traffic to be accommodated matches the ground. Case (b): An optical path is newly installed in a section that minimizes the cost of the newly installed optical path, and packet traffic is accommodated in the route using the optical path.

[Fourth Embodiment] FIG. 9 is a diagram for explaining the fourth embodiment, and FIG. 10 is a flowchart of the fourth embodiment.

In the fourth embodiment, when a request for accommodating specific point-to-point packet traffic occurs, first, the shortest route seen from the optical network 8 (minimum fiber link cost route).
To explore. If it is possible to reach the destination by the existing optical path with the number of hops within the specified number, the existing optical path on this route will accommodate the packet traffic, and if that is not possible, a new optical path will be installed. .

The flowchart (steps S41 to S49) of the fourth embodiment shown in FIG. 10 is almost the same as the flowchart (steps S31 to S39) of the third embodiment shown in FIG. The difference is that the limitation of the number of OLSP hops is taken into consideration when determining the presence or absence of the corresponding optical path. Also, step S47
In the determination, if the search route searched in step S46 exceeds the limit of the number of OLSP hops, it is determined that there is no route that can accommodate the packet traffic.

The fourth embodiment can reduce the number of relay optical paths (that is, the relay packet switch nodes) as compared with the third embodiment, and can reduce the transfer processing load of the packet switch node. .

When a new optical path is installed, the following two cases can be set. Case (a): An optical path is newly established in a section where the packet traffic to be accommodated matches the ground. Case (b): An optical path is newly established and used in a section in which the cost of the newly-established optical path is minimized within a range satisfying the specified number of relay optical paths (that is, relay packet switch nodes). Include packet traffic in the route.

[Fifth Embodiment] FIG. 11 is a diagram for explaining the fifth embodiment, and FIG. 12 is a flow chart of the fifth embodiment.

In the fifth embodiment, when a request for accommodating a specific point-to-point packet traffic occurs, an optical path matching the point of the traffic is newly established. This will be described with reference to FIGS. 11 and 12.

For example, in FIG. 11, if a packet traffic accommodation request is issued between Node # 1 and Node # 3, a route that minimizes the fiber link cost connecting Node # 1 and Node # 3 is selected. Search (step S51). If there is no route to the end node (Node # 3) in the fiber link, that is, if the cost to the end node is infinite, step S5.
Go to 4. If there is a route, an optical path is newly installed in the fiber link of the searched route (rank 1 in FIG. 11), the packet traffic is accommodated, and the packet is transferred (step S53).

If there is no fiber link reaching Node # 3, Node # 1 including the existing optical path link is also included.
To the node # 3 with the lowest cost are searched (step S54). At this time, if necessary O
Consider the limit on the number of LSP hops. If a route reaching Node # 3 is found (step S55), the packet is transferred by that route (step S56). If the route to the end node (Node # 3) is not found even if the existing optical path link is included, the packet transfer is blocked or the packet is discarded (step S57).

In the fifth embodiment, unlike the above-described first to fourth embodiments, the probability that the route in which packet traffic is accommodated matches the shortest route on the fiber link is high. Also, since the packet switch handles only the traffic terminated at its own node,
It is possible to significantly reduce the transfer processing load.

Further, a modification may be made to this fifth embodiment to allow the case where the limit of the number of OLSP hops imposed in step S55 is other than 1. As a result, even if the network is congested and a new optical path cannot be established, or even if the packet traffic cannot be transferred by the OLSP / one hop, it becomes possible to guarantee the accommodation of the traffic, which is a factor for increasing the revenue for the communication carrier.

The first to fifth embodiments can be implemented by combining some of them depending on the state of the network and the service class of the packet traffic to be accommodated.

For example, as a combination of the embodiments, there is a combination in which the fifth embodiment is applied to the high priority class traffic and the first embodiment is applied to the low priority class traffic. .

[0064]

As described above, according to the present invention,
A new dynamic optical path can be set up according to the packet traffic accommodation request, and an optimal new optical path can be set up according to the network load condition.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a network system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a photonic router used in this embodiment.

FIG. 3 is a diagram illustrating the first embodiment.

FIG. 4 is a flowchart of the first embodiment.

FIG. 5 is a diagram illustrating a second embodiment.

FIG. 6 is a flowchart of the second embodiment.

FIG. 7 is a diagram illustrating a third embodiment.

FIG. 8 is a flowchart of the third embodiment.

FIG. 9 is a diagram illustrating a fourth embodiment.

FIG. 10 is a flowchart of the fourth embodiment.

FIG. 11 is a diagram illustrating a fifth embodiment.

FIG. 12 is a flowchart of the fifth embodiment.

[Explanation of symbols]

1-1 to 1-4 Photonic router 2 packet switch 3 optical switch 4,4 'optical path 5 fibers 6 traffic 7 Packet network 8 optical networks

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04B 10/14 (72) Inventor Eiji Oki 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Yoshihiro Takigawa 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-Term (Reference) within Nippon Telegraph and Telephone Corporation 5K002 DA05 DA09 EA03 FA02 5K030 GA03 GA13 HA08 JA14 JL03 KA05 LC01 LC09 MB09

Claims (5)

[Claims] 1. An optical path is newly provided in a multi-layer network including a packet network including an optical path link and a packet switch, and an optical network including the packet network and including an optical switch and a fiber link. A method for accommodating specific point-to-point packet traffic is performed by searching for a route that minimizes the optical path link cost seen from the packet network. A new optical path construction method, which is performed only when it is impossible to reach the destination. 2. The optical path new installation method according to claim 1, wherein the new optical path is installed when it is impossible for the accommodated packet traffic to reach the destination by an existing optical path within a predetermined number of hops. A new optical path installation method characterized in that 3. An optical path is newly provided in a multi-layer network including a packet network composed of optical path links and packet switches, and an optical network accommodating the packet networks and composed of fiber links and optical switches. A method for accommodating specific point-to-point packet traffic is performed by searching for a route that minimizes the fiber link cost seen from the optical network. A new optical path construction method, which is first performed when it is impossible to reach the destination by the path. 4. The optical path new installation method according to claim 3, wherein the new optical path is installed when it is impossible for the accommodated packet traffic to reach the destination by an existing optical path within a predetermined number of hops. A new optical path installation method characterized in that 5. A new optical path is provided in a multi-layer network including a packet network including an optical path link and a packet switch, and an optical network including the packet network and including a fiber link and an optical switch. The method is characterized in that a new optical path is established in response to a request for accommodation of specific point-to-ground packet traffic, and at that time, the new optical path is established on the route that minimizes the fiber link cost seen from the optical network. How to install a new optical path.