JP2006033235A - Path control method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a path control method and apparatus for a network divided into a plurality of areas and managed that selects a boundary router to optimize a path bridged over areas even when a plurality of boundary routers located at a boundary with a backbone area exist. <P>SOLUTION: An edge node Ra1 going to execute traffic engineering outputs a path optimizing request REQ1 to each of the boundary nodes Rb1, Rb2, each of the boundary nodes Rb1, Rb2 independently carries out optimum path searching, informs the edge node Ra1 about the results of notices RES1, RES2, and the edge node Ra1 determines an optimum final path by taking into account the path information of its own area on the basis of the notices. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a route control method and apparatus, and more particularly to a method and apparatus (router or node) for routing control of IP packets flowing in a network divided into a plurality of areas.

  The Internet is currently spreading rapidly, with the intention of handling all communication applications over the Internet Protocol (IP). The Internet originally has a connectionless network architecture that does not establish a connection, and is routed to an outgoing route based on a destination address described in an IP packet. In other words, in the router having the function, when the IP packet arrives, the IP packet is simply transferred to the outgoing route corresponding to the IP address.

  In the Internet having such a network architecture, a route determination protocol called a routing protocol is handled between routers in order to determine which IP address is transferred to which outgoing route.

  Currently, a method using the Dijkstra algorithm is generally used as an algorithm for a routing protocol, but such a current routing protocol has the following problems.

 • Only the shortest path first (SPF) route to the destination can be selected.

 A routing protocol is executed only when the network topology changes.

  That is, once a route is determined, IP packets are transferred only to that route, and chronic congestion occurs. Further, since only the shortest distance can be set, there is a problem that even if a certain route is congested, the empty route cannot be used even though another route is free.

  As a conventional technique for solving such a problem, in Japanese Patent Laid-Open No. 2001-320420 (Patent Document 1), an MPLS technique is used, a label path that can be set by MPLS is used, and explicit route setting that is not SPF can be performed. . In Patent Document 1, a path is first set between a source node and a destination node using MPLS technology, and when the path is congested, a path other than SPF is newly set, and traffic is detoured to the new path. Or performing dynamic load balancing using both paths.

  However, the problem with this method is that only one area is assumed as the network area. In a routing protocol generally used in the Internet, a network is divided into a plurality of areas, routing information in the area is summarized and notified to an external area, and scalability is improved. The OSPF routing protocol is common, but in OSPF, a normal area is connected to an area called the backbone area to form a network.

  An example of the configuration of such a network is shown in FIG. In this example, the network is divided into four areas NWa to NWd, and the areas NWa, NWc, and NWd are connected to each other via the backbone area NWb. The area NWa includes routers (nodes) Ra1, Ra2, and Ra3, and is connected to the backbone area NWb via an border router (gateway router) Rb1. The area NWc includes routers Rc1 to Rc4, and the backbone area NWb and the area NWc are connected via the router Rc1. Similarly, the area NWd includes routers Rd1 to Rd3, and is connected to the backbone area NWb with the router Rd1 as a border router.

  In order to guarantee the bandwidth, each of the areas NWa to NWd is closed within the area and exchanges route information. Then, outside the area, the route information in the area is summarized and transmitted. For example, the border router Rb1 summarizes the route information of the backbone area NWb that it manages and notifies the area NWa, and also summarizes the route information of the area NWa and notifies the backbone area NWb. The same applies to the border router Rc1 between the backbone area NWb and the area NWc and the border router Rd1 between the backbone area NWb and the area NWd.

  As a result, the information managed by each router is reduced, and the scalability of the entire network is improved.

  However, as shown in the figure, when connections are set from router (edge router) Ra1 to router (edge router) Rc4, and congestion CGT occurs in backbone area NWb, where is congestion occurring from router Ra1? There is a problem that it cannot be explicitly known, and even if an attempt is made to rearrange the route, the route information is unknown and the rearrangement cannot be performed.

  As described above, since information in the area is concealed outside the area, it is difficult to calculate an optimum route between the edge routers. The route calculation in the network closed in the area can be calculated in the router in the area, but the route calculation across the area cannot be calculated when the current framework is used.

As another prior art, there is an optimum route calculation method when the network is divided into a plurality of areas as disclosed in JP-A-2002-190825 (Patent Document 2). The route is optimally calculated.
JP 2001-320420 A JP 2002-190825

  However, in Patent Document 2 described above, when there are a plurality of boundary nodes located at the boundary with the backbone area, it is difficult to select a boundary node and optimize a route across the area.

  Therefore, according to the present invention, in a network routing control method and apparatus that is divided into a plurality of areas and managed, even when there are a plurality of boundary nodes (routers) positioned at the boundary with the backbone area, It is an object to optimize a route that spans the two.

  In order to solve the above-described problem, a route control method according to the present invention includes a first step in which a node (router) in an area to perform traffic engineering exchanges route information with each boundary node, and the exchange And a second step of determining an optimal route based on the route information.

  Here, in the first step described above, the edge node to perform the traffic engineering issues a route optimization request request to each boundary node, and each boundary node independently performs an optimum route search, The result is notified to the edge node, and in the second step, the edge node can determine an optimum final route in consideration of route information of its own area.

  In the first step, each boundary node independently performs an optimum route search. The result is arbitrated between the boundary nodes, and the result of the arbitration is notified to the edge node. In this step, the edge node may determine an optimum final route in consideration of route information of its own area.

The present invention will be described below with reference to the principle diagram (1) shown in FIG.

  First, in this principle diagram (1), two border routers Rb1 and Rb2 exist as border routers (nodes) between the area NWa and the backbone area NWb with respect to the general network configuration example shown in FIG. Assume that As in the network configuration example shown in FIG. 21, when the connection from the edge router Ra1 to the edge router Rc4 via the routers Ra2, Rb2, Rc1, and Rc2 is established, the backbone area NWb When congestion CGT occurs, the edge node Ra1 of the area NWa to perform traffic engineering issues a route optimization request (path relocation order) REQ1 to the border routers Rb1 and Rb2 with the backbone area NWb .

  The border routers Rb1 and Rb2 that have received this request REQ1 independently search for an optimum route (shown by a dotted line) to the border node Rc1 located in the facing area NWc. As a result of the search, the border routers Rb1 and Rb2 return responses RES1 and RES2 to the edge router Ra1, respectively. The edge router Ra1 determines and sets the optimum final route from the route information notified from the border routers Rb1 and Rb2 in consideration of the optimum route information in its own area NWa.

  In this case, instead of the border routers Rb1 and Rb2 separately notifying the edge router Ra1 of the search results RES1 and RES2, arbitration is performed between the border routers Rb1 and Rb2, and the arbitration result is notified to the edge node Ra1. In response, the edge node may determine the final final route in consideration of the optimum route information in its area NWa.

  Further, in the route control method according to the present invention, an area that exists between the first area and the backbone area and that faces the area through the backbone area from the first boundary node that is to perform the traffic engineering. When there are a plurality of boundary nodes to go to, in the first step, the first boundary node issues a route optimization request to the second boundary node, and each second boundary node is independent. Search for the optimum route, notify the first boundary node of the result, and in the second step, the first boundary node considers the route information of its own area in the second step. A final route may be determined.

  Also in this case, in the first step, the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimum route search. The result is arbitrated between the second boundary nodes, the result of the arbitration is notified to the first boundary node, and in the second step, the first boundary node The optimum final route may be determined in consideration of the route information of the area.

The above-described present invention will be described below with reference to the principle diagram (2) shown in FIG.

  In this principle diagram (2), there is one border router Rb1 between the area NWa and the backbone area NWb, but there are two border routers Rc1 and Rc5 between the backbone area NWb and the area NWc. Suppose it exists.

  Similarly to the above, it is assumed that congestion CGT has occurred in the area NWc while the connection from the edge router Ra1 to the edge router Rc4 via the routers Ra2, Rb1, Rc5, and Rc2 has been established. .

  The border router Rb1 issues a route optimization request REQ1 to the border routers Rc1 and Rc5, and each of these border routers Rc1 and Rc5 independently searches for the optimum route (shown by a dotted line) to the edge router Rc4. Each of them returns responses RES1 and RES2 to the border router Rb1. The border router Rb1 determines and sets the optimum final route in consideration of the route information that has been responded and the optimum route information that it has searched for in the backbone area NWb.

  Also in this case, instead of separately sending the responses RES1 and RES2 to the border router Rb1, the border routers Rc1 and Rc5 both arbitrate the optimum route and send the mediation result to the border router Rb to obtain the optimum final A route may be determined.

  Further, in the route control method according to the present invention, there are a plurality of first boundary nodes for going from the first area to the backbone area, and the second boundary nodes facing each other through the backbone area from the first boundary node. When there are a plurality of second boundary nodes to go to the area, in the first step, the edge node to perform traffic engineering issues a route optimization request to each boundary node, and each boundary node Performs an optimum route search independently and issues a route optimization request to each second boundary node. Each second boundary node independently performs an optimum route search, and the result is obtained for each first boundary node. Each of the first boundary nodes notifies the edge node of the optimum route from each second border node and the optimum route of its own area, and the second step , The edge node from among them may determine the optimum final route taking into account the routing information of their area.

  Also in this case, in the first step, the edge node that is to perform the traffic engineering issues a route optimization request to each first boundary node, and each first boundary node is independently optimized. A route search is performed and a route optimization request is sent to each second boundary node. Each second boundary node independently performs an optimum route search, and the result is arbitrated between the second boundary nodes. The mediation result is notified to each first boundary node, and further mediation is performed between the first boundary nodes based on the mediation result and the optimum route of the area, and the mediation result is sent to the edge. The node may be notified, and in the second step, the edge node may determine an optimum final route in consideration of the arbitration result and route information of its own area.

The present invention will be described below with reference to the principle diagram (3) shown in FIG.

  In this principle diagram (3), the above principle diagrams (1) and (2) are roughly combined, and there are two border routers Rb1, between the area NWa and the backbone area NWb. Assume that Rb2 exists and that two border routers Rc1 and Rc5 exist between the backbone area NWb and the area NWc.

  Then, in the connection established between the edge node Ra1 and the edge node Rc4, if congestion CGT1 occurs in the area NWa, congestion CGT2 occurs in the backbone area NWb, or congestion CGT3 occurs in the NWc, the edge The router Ra1 issues a route optimization request REQ1 toward the edge node Rc4 to the border routers Rb1 and Rb2.

  On the other hand, the border routers Rb1 and Rb2 further issue a route optimization request REQ2 to the border routers Rc1 and Rc5. The border routers Rc1 and Rc5 search the optimum routes (shown by dotted lines) to avoid the congestion CGT3 to the edge router Rc4 independently of each other, and the search results are respectively sent as responses RES1 and RES2 to the border routers Rb1 and Rb2. Notice.

  The search results RES1 and RES2 are further notified to the edge router Ra1 as responses REW3 and RES4, and the edge router Ra1 considers the notified search results and optimum route information that avoids congestion CGT1 in its own area NWa. The optimum route to the edge router Rc4 is determined.

  In this case as well, the border routers Rb1 and Rb2 naturally include the optimum route information to avoid the congestion CGT2 in their backbone area NWb in the responses RES3 and RES4, and notify the edge router Ra1. The optimum final route is determined in consideration of the above.

  In this principle diagram (3), as in the above principle diagrams (1) and (2), the border routers Rc1 and Rc5 independently send the search results to the border routers Rb1 and Rb2. The search results are arbitrated between the routers, the arbitration results are notified to the border routers Rb1 and Rb2, and the border routers Rb1 and Rb2 perform arbitration in the same manner and return the mediation results to the edge router Ra1. Also good.

  In the first step described above, the exchange of route information between a node in a certain area where the traffic engineering is to be performed and each boundary node is an OSPF Opaque LSA which is a routing protocol, or a signaling protocol. This can be done using RSVP-TE.

  As a path control device that realizes the path control method according to the present invention, a node in an area where traffic engineering is to be performed includes first means for exchanging path information with each boundary node; And a second means for determining an optimal route based on the route information.

  Here, the node of the area where the traffic engineering is to be performed is an edge node, and the first means issues a route optimization request to each boundary node, and each boundary node independently has an optimum route. The search is performed, the result is notified to the edge node, and the second means can determine the optimum final route from among the edge node in consideration of the route information of its own area.

  Further, the node of the area where the traffic engineering is to be performed is an edge node, and the first means is that the edge node which is to perform the traffic engineering issues a route optimization request request to each boundary node, and The boundary node independently searches for the optimum route, mediates the result between the boundary nodes, notifies the edge node of the mediation result, and the second means considers the route information of its own area. And an optimal final route can be determined.

  Furthermore, when there are a plurality of boundary nodes that exist between the first area and the backbone area and that go from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area The first means of the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimum route search, and the result Can be notified to the first boundary node, and the second means of the first boundary node can determine the optimum final route in consideration of the route information of its own area.

  Furthermore, when there are a plurality of boundary nodes that exist between the first area and the backbone area and that go from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area The first means of the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimum route search, and the result Between the second boundary nodes, the result of the arbitration is notified to the first boundary node, and the second means of the first boundary node transmits the arbitration result and route information of its own area. Thus, an optimal final route can be determined.

  Furthermore, there are a plurality of first boundary nodes for going from the first area to the backbone area, and a second boundary for going from the first boundary node to the second area facing the backbone area through the backbone area. When there are a plurality of nodes, the first means of the edge node that intends to perform traffic engineering issues a route optimization request to each boundary node, and each boundary node performs an optimum route search independently. In addition, a route optimization request is issued to each second boundary node, each second boundary node independently performs an optimum route search, and the result is notified to each first boundary node. Border node notifies the edge node of the optimum route from each second border node and the optimum route of its area, from which the second means of the edge node It is possible to determine the optimal final pathway in consideration of the road information.

  Furthermore, there are a plurality of first boundary nodes for going from the first area to the backbone area, and a second boundary for going from the first boundary node to the second area facing the backbone area through the backbone area. When there are a plurality of nodes, the first means of the edge node that intends to perform traffic engineering issues a route optimization request to each boundary node, and each first boundary node is independently an optimum route. Performs a search and issues a route optimization request to each second boundary node. Each second boundary node performs an optimum route search independently, and arbitrates the results between the second boundary nodes. The mediation result is notified to each first boundary node, and further mediation is performed between the first boundary nodes based on the mediation result and the optimum route of the area, and the mediation result is transmitted to the first boundary node. Notify the node, it can be the second means of the edge node to determine the optimal final pathway in consideration of the route information of the arbitration result and their areas.

  The first means described above is used for exchanging route information between a node in an area where the traffic engineering is to be performed and each boundary node, an OSPF Opaque LSA which is a routing protocol, or an RSVP which is a signaling protocol. Can be done using -TE.

  According to the present invention, in a node in an area where route optimization (traffic engineering) is to be performed, route search is performed by exchanging route information between the node and a plurality of boundary nodes located at the boundary of the area. Because the search result is notified to the node that is trying to optimize the route and the optimum search of the route across the area is performed, even if there are multiple boundary nodes located at the boundary with the backbone area By selecting a boundary node, it is possible to determine and set an optimum route across the area.

  FIG. 4 shows an embodiment of each router (node) used in the network as shown in FIGS. This router 1 uses MPLS (Multi Protocol Label Switching) packet transfer technology, and IP packet transfer unit 2 that inputs and outputs IP packets and other routers connected to this IP packet transfer unit 2 A routing protocol unit 3 that performs information flooding and collects (1) statistical (route) information about other routers, and a normal route calculation unit 4 that is connected to the routing protocol unit 3 and calculates a normal route (route) The MPLS label is generated and managed based on the calculation result by the normal path calculation unit 4, and when a congestion state occurs, the congestion state is detected (2) and, if necessary, the border router LSP management unit 5 that outputs a label path along the route based on an output signal from traffic engineering unit 6 that issues a candidate search request (3) for an optimal route to LSP, and LSP An LSP signaling unit 7 that receives the LSP label from the processing unit 5 and sets the LSP for other routers, and performs route setting (4) based on the response from the border router as necessary It is out. Note that information flooding from the routing protocol unit 3 and LSP setting from the LSP signaling unit 7 are indicated by dotted lines, but these dotted lines indicate that they are executed by control packets.

  FIG. 5 shows an embodiment of the traffic engineering unit 6 in the router 1 shown in FIG. In this embodiment, the traffic engineering unit 6 is connected to the IP packet transfer unit 1 and inputs traffic characteristic information, and is connected to the load protocol unit 2 for observing various loads, and the routing protocol unit 2 to be connected to the other. A traffic engineering database (DB) 62 that collects route information about the router, and a traffic engineering calculation unit 63 that performs congestion detection based on the route information stored in the traffic engineering DB 62 and provides the information to the LSP management unit 5 It is configured.

  FIG. 6 shows a generally known operation at the time of initial setting of such a router. First, the routing protocol units 2 in each router perform information flooding to grasp the network topology (step T1). Based on the network topology of the routing protocol unit 2, the normal route calculation unit 3 calculates the shortest route between edge routers or between edge routers and boundary routers, and instructs the LSP management unit 5 to set a route (step T2). . Receiving the route setting instruction, the LSP management unit 5 instructs the LSP signaling unit 5 which label route to use or a label path setting instruction (step T3). The LSP signaling unit 5 performs signaling to other routers and performs path setting in order to perform LSP setting (step T4).

  After the initial setting as described above, various operations based on the present invention described below are executed.

Example of operation (1) (See Fig. 7 and Fig. 1)
This operation example (1) relates to the principle diagram (1) shown in FIG. 1, and its flowchart is shown in FIG.

  First, the load monitoring unit 61 in the traffic engineering unit 6 of the router 1 inputs the traffic characteristic information from the IP packet forwarding unit 2, and detects the congestion CGT in the backbone area NWb as the edge router Ra1 trying to perform the traffic engineering It is determined whether or not (step S1). As a result, when it is found that congestion has occurred in the backbone area NWb, the traffic engineering DB 62 and the traffic engineering calculation unit 63 of the edge router Ra1 are connected to the boundary between their own area NWa and the backbone area NWb. An optimum route candidate search request REQ1 is made to the routers Rb1 and Rb2 (step S2).

  The traffic engineering DB 62 and the traffic engineering calculation unit 63 of the boundary routers Rb1 and Rb2 that have received the candidate search request REQ1 determine the optimum route for each of the boundary routers Rb1 and Rb2 to avoid the congestion CGT in the backbone area NWb to which it belongs. Search for candidates (step S3).

  Hereinafter, similarly, in the traffic engineering unit 6, the load observation unit 61, the traffic engineering DB 62, and the traffic engineering calculation unit 63 cooperate.

  Details of step S3 are shown in FIG. 8 (1). First, each of the boundary routers Rb1 and Rb2 masks a link (path) where the congestion link CGT on the topology database (traffic engineering DB) 62 occurs (step S3-1). That is, in the configuration example of the backbone area NWb shown in FIG. 2B, the congested link between the router Rb4 and the border router Rc1 of the area NWc facing the router Rb4 in the routers Rb1 to Rb6 configuring the backbone area NWb is masked. It will be.

  Next, a route with the most free bandwidth is searched using the topology database 62 masking the congestion link (step S3-2). In the case of border router Rb1, as shown in backbone area NWb shown in (3) in the figure, this is the route x1-y1 from border router Rb1 to Rc1, as shown in bold lines in (4) in the figure. Since -z1 is 100 Mbps, this route is searched for as the route with the most free bandwidth for the border router Rb1. Similarly, for the border router Rb2, the route indicated by the bold line on the lower side of FIG.

  Then, from such route information, a list of IP addresses of routers in the backbone area NWb passing through the route is created (step S3-3). In the example shown in (3) in the figure, a list of IP addresses of routers Rb3 and Rc1 is created for border router Rb1, and a list of IP addresses of routers Rb5 and Rb6 is created for border router Rb2. It will be.

  Returning to FIG. 7, the border routers Rb1 and Rb2 individually respond to the requesting edge router Ra1 with the IP address obtained in step S3-3 and the free bandwidth value obtained in step S3-2. RES1 and RE2 are returned (step S4).

  After this, the edge router Ra1 selects the final optimum route in consideration of the optimum route information (router IP address and free bandwidth value) of the backbone area NWb that has been returned and the optimum route information of the area NWa to which it belongs. (Step S5).

  Details of this step S5 are shown in FIG. 9 (1). First, the edge router Ra1 searches for a route to the border routers Rb1 and Rb2 (step S5-1). As a result, as indicated by the thick line in FIG. 2 (2), the optimal route from the edge router Ra1 to the border router Rb1 is the route v1-w1, and from the edge router Ra1 to the border router Rb2, the route v2-w2 is Indicates that it has been searched.

  Then, the edge router Ra1 selects a border router and a route based on information (route and bandwidth) notified from the border routers Rb1 and Rb2 (step S5-2). An example of selection in this case is shown in FIG. 3 (3). In case 1, the route 1 = v1-w1-x1-y1-z1 from the edge router Ra1 via the border router Rb1 is searched, Route 2 from edge router Ra1 via border router Rb2 = v2-w2-x2-y2-y3-z1 is searched, but route 1 is selected because route 1 has fewer hops than route 2 as shown Will do.

  Or, as in case 2, the free bandwidth of route 1 is 1 Mbps, and the free bandwidth of route 2 is 100 Mbps, so route 2 has more hops than route 1, but route 2 is selected because the free bandwidth is large Will be.

  In this way, after the edge router Ra1 selects the optimum route in step S5, a route from the edge router Ra1 to the border router Rc4 belonging to the area NWc on the opposite side of the backbone area NWb is set (step S6). ).

  Then, it is determined whether or not the route setting is completed (step S7). If the route setting is not completed, the process returns to the start (step S8), but when the route setting is completed, this operation is finished.

Example of operation (2) (See Fig. 10 and Fig. 1)
This operation example (2) is also related to the principle diagram (1) shown in FIG. 1. In FIG. 10 showing the flowchart, the process in step S40 is changed to step S4 in the operation example (1) shown in FIG. Is different. In other words, in this step S40, the border routers Rb1 and Rb2 do not reply to the edge router Ra1 separately, but the border routers Rb1 and Rb2 communicate with each other to adjust the optimum routes within the backbone area NWb. Then, the response to the edge router Ra1 is made.

  Details of this step S40 are shown in FIG. 11 (1). That is, first, in the configuration example of the backbone area NWb shown in FIG. 8 (2), as indicated by the thick line in FIG. 8 (3), the boundary is the same as in the operation example (1) shown in FIG. After route 1 and route 2 in each backbone area NWb of routers Rb1 and Rb2 are selected, border routers Rb1 and Rb2 exchange free bandwidth information with searched routes 1 and 2 (step S40-1). . Then, the optimum route is selected in consideration of the number of hops and the available bandwidth, and each is returned to the edge router Ra1 (step S40-2).

  FIG. 4 (4) shows two cases. In case 1, route 1 = x1-y1-z1 and route 2 = x2-y2-y3-z1, so route 1 is more than route 2 Route 1 is selected because the number of hops is small. In case 2, the free bandwidth of route 1 is 1 Mbps, and the free bandwidth of route 2 is 100 Mbps, so route 2 has more hops than route 1 but has a larger free bandwidth, so route 2 is selected. It will be.

  Thereafter, by executing steps S5 to S8, in the case 1 shown in FIG. 11 (4), the route searched by the edge router Ra1 for its own area NWa as shown in FIG. 9 (2) In consideration of the information, as in case 1 shown in FIG. 3C, the route 1 by the edge router Ra1, router Ra2, border router Rb1, router Rb3, border router Rc1 is determined. In case 2 as well, an optimal route can be determined in the same manner.

Example of operation (3) (See Fig. 12 and Fig. 2)
This operation example (3) relates to the principle diagram (2) shown in FIG. 2. In FIG. 12 showing the flowchart, the congestion CGT in the area NWc in the established connection from the edge router Ra1 to the edge router Rc4 is shown. The point where this occurred is also assumed. Therefore, the border router between the area NWa and the backbone area NWb is one router Rb1, and between the backbone area NWb and the area NWc, two border routers Rc1 and Rc5 are arranged, and thus the backbone area NWb And the area NWc are similar to the relationship between the area NWa and the backbone area NWb in the principle diagram (1) shown in FIG.

  First, the border router Rb1 of the backbone area NWb that is to perform traffic engineering determines whether congestion has occurred in the facing area NWc (step S11).

  As a result, since the border router Rb1 knows that the congestion CGT is generated in the area NWc as in the example shown in FIG. 2, the border router Rb1 is connected to the two border routers Rc1 and Rc5 in the opposite area NWc. An optimum route candidate search request REQ1 is made (step S12).

  The border routers Rc1 and Rc5 that have received such a search request REQ1 independently search for the optimum route candidates that the border routers Rc1 and Rc5 avoid the congestion CGT in their own area NWc (step S13).

  The details of step S13 are shown in FIG. 13 (1), and steps S13-1 to S13-3 constituting step S13 are basically steps of the operation example (1) shown in FIG. 8 (1). This corresponds to the specific steps S3-1 to S3-3 of S3. However, step S13-3 is different in that a list of router IP addresses in the area NWc is created.

  Therefore, the configuration example of the area NWc shown in FIG. 13 (2) corresponds to the configuration example of the backbone area NWb shown in FIG. 8 (2), and the search route shown in FIG. This corresponds to the searched route shown in 8 (3). As a result, as shown in FIG. 13 (4), the response information to the border router Rb1 is route = x1-y1-z1 and free bandwidth = 100 Mbps.

  Returning to FIG. 12, in step S14, each of the border routers Rc1 and Rc5 separately obtains the IP address of the router obtained in step S13-3 with respect to the requesting border router Rb1, and in step S13-2. Notify available bandwidth information.

  The border router Rb1 that has received such a notification compares the route information of the facing area NWc notified from the border routers Rc1 and Rc5, and considers the optimum route information of the backbone area NWb to which it belongs and determines the optimum final route. Select (step S15).

  The details of step S15 are shown in FIG. 14 (1). This flowchart corresponds to the flowchart shown in FIG. 9 (1), but in step S15-1, the border router Rb1 A route to border routers Rc1 and Rc2 in area NWc is searched. As shown in the configuration example of Fig. 14 (2), the route v1-w1 via the router Rb2 is searched from the border router Rb1 to the border router Rc1, and the route router Rb1 to the border router Rc5 is routed through the router Rb3. This indicates that the route v2-w2 is searched.

  In step S15-2, a border router and a route are selected based on information (route and bandwidth) returned from the border routers Rc1 and Rc5. That is, as shown in FIG. 2B, the boundary router Rc1 searches for the optimum route x1-y1 with the edge router Rc4, and the boundary router Rc5 similarly with the edge router Rc4 Since y2-y3 has been searched and this information is notified to the border router Rb1, the route information collected by the border router Rb1 is as shown in FIG.

  Also in this case, case 1 and case 2 are shown. In case 1, path 1 = v1-w1-x1-y1-z1 and path 2 = v2-w2-x2-y2-y3-z1 are This indicates that route 1 is selected because the number of hops is small, and in case 2, route 2 is selected because route 2 has a larger available bandwidth even if it has more hops than route 1. Is shown. These also correspond to the case shown in FIG. 9 (3).

  Thereafter, by executing steps S16 to S18, an optimum route from the border router Rb1 to the edge router Rc4 is set.

Example of operation (4) (See Fig. 15 and Fig. 2)
In the case of this operation example (4), basically the same processing as the operation example (3) shown in FIG. 12 is performed based on the principle diagram (2) shown in FIG. As described above, step S140 is different from step S14 in the operation example (3). That is, in this step S140, the border routers Rc1 and Rc5 do not return responses to the border router Rb1 separately, but they communicate with each other and adjust the optimal route in the opposite area NWc before replying. Is different.

  Details of step S140 are shown in FIG. 16 (1). That is, in step S140-1, in the configuration example of the facing area NWc shown in FIG. 2B, the border routers Rc1 and Rc5 exchange the searched route and free bandwidth information.

  That is, as shown in FIG. 3 (3), the route x1-y1 via the router Rc2 is searched between the border router Rc1 and the edge router Rc4, and the router Rc3 is located between the border router Rc5 and the edge router Rc4. And the route x2-y2-y3 via Rc7 are searched for, but the searched information is exchanged between the border routers Rc1 and Rc5, and as shown in step S140-2, the number of hops, The route is selected considering the bandwidth. In this example, as shown in Figure 4 (4), route 1 has fewer hops than route 2 in case 1, so route 1 is selected, and route 2 has more hops than route 1 as in case 2. However, there are cases where the route 2 is selected because the free bandwidth is large.

  After that, by passing through steps S15 to S18 in the same manner as described above, the optimum route from the border router Rb1 to the edge router Rc4 in the facing area NWc is selected and set.

Example of operation (5) (See Figures 17 and 3)
This operation example (5) relates to the principle diagram (3) shown in FIG. 3, and as shown in the flowchart of FIG. 17, in this operation example (5), in the connection from the edge routers Ra1 to Rc4, As shown in the figure, it is assumed that any of the congestions CGT1 to CGT3 occurs.

  First, the edge router Ra1 determines whether or not congestion other than its own area NWa has been detected (step S21). In this case, the edge router Ra1 does not execute the following process when the congestion CGT1 is detected, and proceeds to the following process only when the congestion CGT2 or CGT3 is detected.

  That is, when it is detected that there is congestion in the backbone area NWb or the area NWc, the edge router Ra1 first sends an optimum route candidate search request REQ1 to the boundary routers Rb1 and Rb2 of the backbone area NWb (step S22). .

  The border routers Rb1 and Rb2 that have received such a search request REQ1 determine whether or not congestion CGT3 is detected in the facing area NWc through which the requested route passes (step S23). As a result of this determination, if congestion in the facing area NWc is not detected, it means that congestion CGT2 in the backbone area has been detected, so the process proceeds to step S27, but it is understood that congestion CGT3 in the facing area NWc has been detected. If so, the process proceeds to step S24, and the border routers Rb1 and Rb2 in the backbone area NWb send candidate search requests REQ2 for the optimum route to the border routers Rc1 and Rc5 in the opposite area NWc.

  The border routers Rc1 and Rc5 that have received such a search request REQ2 search for an optimum route in which the border routers Rc1 and Rc5 avoid congestion in the area NWc (step S25).

  Then, the border routers Rc1 and Rc5 separately respond to the search results to the requesting border routers Rb1 and Rb2 (step S26).

  Further, the border routers Rb1 and Rb2 search for an optimum route for avoiding congestion in the backbone area NWb of the border routers Rb1 and Rb2, and return the result to the edge router Ra1. In this case, since there are responses from the border routers Rc1 and Rc5, the responses RES3 and RES4 are also returned together (step S27). When the process proceeds from step S23 to step S27, that is, when congestion CGT2 in the backbone area occurs, the process in step S27 is the same as step S3 in the operation example (1) in FIG.

  After step S27, the edge router Ra1 considers the returned route information, further considers the optimum route information searched in its own area NWa, and selects the optimum route to the edge router Rc4 in the opposite area NWc. A route will be set.

  Details of this step S28 are shown in FIG. Now, a network configuration example more specifically showing the network shown in the principle diagram (3) shown in FIG. 3 is shown in FIG. 18 (2). In step S28-1 constituting step S28, first, A route from the edge router Ra1 to the border routers Rb1 and Rb2 is searched. As a result, in the area NWa shown in FIG. 2B, as indicated by the bold line, the route from the edge router Ra1 to the border router Rb1 is the route v1-w1 through the router Ra2 and the route v2- through the router Ra3. w4 is searched. From the edge router Ra1 to the border router Rb2, a route v1-w3 passing through the router Ra2 and a route v2-w2 passing through the router Ra3 are searched.

  In step S28-2 constituting step S28, the edge router Ra1 selects a border router and a route based on information (route and bandwidth) returned from the border routers Rb1 and Rb2. In this case, the border routers Rb1 and Rb2 are notified of the route z1-z3 as the optimum route from the border router Rc1 to the edge router Rc4, and the border router Rc5 is notified of the route z2-z4.

  Then, between the border routers Rb1, Rb2 and the border routers Rc1, Rc5, the route router Rb1 searches the border router Rc1 for the route x1-y1 via the router Rb3, and the border router Rb1 to the border router Rc5. On the other hand, the route x1-y4 via the router Rb3 is searched, the route x3-y1 via the router Rb4 is searched from the border router Rb2 to the border router Rc1, and the route router Rb2 to the border router Rc5. On the other hand, since the route x2-y2-y3 via the routers Rb5 and Rb6 is searched, the route returned to the edge router Ra1 in the network configuration example shown in FIG. 18 (2) is shown in FIG. It becomes route 1-route 8.

  Therefore, among the routes 1 to 8, the route 1, 2, 5, and 6 have the smallest number of hops, and the route 6 has the largest bandwidth, so the route 6 is selected with the bandwidth as a priority. It will be.

Example of operation (6) (See Fig. 19 and Fig. 3)
This operation example (6) also corresponds to the principle diagram (3) shown in FIG. 3, but as can be seen by comparing the flowchart of the operation example (5) shown in FIG. 17 with the flowchart of FIG. Steps S260 to S280 are different in that they are processed instead of steps S26 to S28 in the operation example (5).

  That is, in step S260, similarly to the above operation examples (2) and (4), the border routers Rc1 and Rc5 arbitrate the route of their own area NWc and respond to the requesting border routers Rb1 and Rb2. It is a response.

    In step S270, border routers Rb1 and Rb2 also arbitrate the optimal route to avoid congestion in their backbone area NWb, and when there is a reply from border routers Rc1 and Rc5, consider that route as well. Answer one optimal route.

  Further, in step S280, the edge router Ra1 considers the returned route and selects the optimum route to the edge router Rc4 in the opposite area NWc to set the route.

  Details of step S280 are shown in FIG. That is, in step S280-1 constituting step S280, a route from the edge router Ra1 to the border routers Rb1 and Rb2 is searched. At this time, as a result of the adjustment performed in step S270, the edge router Ra1 is informed which of the boundary routers Rb1 and Rb2 has been selected to search for the optimum route. ), The edge router Ra1 searches for the route v1-w1 and the route v2-w4 up to the border router Rb1, assuming that the border router Rb1 has been adjusted. . This state is shown in FIG. At this time, since the border routers Rb1 and Rb2 have obtained the arbitration result between the border routers Rc1 and Rc5 in step S260, the optimum route in the route to the arbitrated border router is obtained based on the arbitration result. It will be sufficient to select.

In the example of FIG. 20 (2), the route z2-z4 from the border router Rc5 to the edge router Rc4 is selected in step S260, and this is notified to the border routers Rb1 and Rb2, and these border routers Rb1 and Rb2 In step S270, there are x1-y4-z2-z4 and x2-y2-y3-z2-z4 routes from the border router Rb1 to the border router Rc5. As a result of the arbitration, the route x1-y4 is routed from the border router Rb1. Is selected, and route information in a form in which routes z2-z4 from the border router Rc5 to the edge router Rc4 are added is sent to the edge router Ra1. Therefore, the edge router Ra1 indicates that the route v1-w1-x1-y4-z2-z4 is selected in step S280.
In the above embodiment, a router is used as a node. However, various devices can be used as long as they have the same function.

(Appendix 1)
When a network is divided into a plurality of areas and managed, each area is connected via a backbone area, and there are a plurality of boundary nodes between at least one area and the backbone area. ,
A node in an area where traffic engineering is to be performed
A first step of exchanging route information with each boundary node;
A second step of determining an optimum route based on the exchanged route information;
A path control method comprising:
(Appendix 2) In Appendix 1,
In the first step, an edge node to perform traffic engineering issues a route optimization request to each boundary node, and each boundary node independently performs an optimum route search, and the result is obtained as the edge node. A route control method comprising: notifying a node, and determining, in the second step, an optimum final route from among the edge node in consideration of route information of its own area.
(Appendix 3) In Appendix 1,
In the first step, the edge node to perform the traffic engineering issues a route optimization request to each boundary node, and each boundary node independently performs an optimum route search, and the result is obtained for each boundary node. It is characterized that mediation is performed between nodes, the result of mediation is notified to the edge node, and in the second step, the edge node determines an optimum final route in consideration of route information of its own area. Route control method.
(Appendix 4) In Appendix 1,
When there are a plurality of boundary nodes that exist between the first area and the backbone area and are directed from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area, In the first step, the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimum route search, and the result is Route control characterized in that the first boundary node is notified, and in the second step, the first boundary node determines an optimum final route in consideration of route information of its own area. Method.
(Appendix 5) In Appendix 1,
When there are a plurality of boundary nodes that exist between the first area and the backbone area and are directed from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area, In the first step, the first boundary node issues a route optimization request to the second boundary node, and each second boundary node performs an optimum route search independently, Arbitration is performed between the second boundary nodes, and the result of the arbitration is notified to the first boundary node. In the second step, the first boundary node displays the arbitration result and route information of its own area. A route control method characterized in that an optimum final route is determined in consideration.
(Supplementary Note 6) In Appendix 1, there are a plurality of first boundary nodes for going from the first area to the backbone area, and going from the first boundary node to the second area facing each other through the backbone area. When there are a plurality of second boundary nodes, in the first step, the edge node to perform traffic engineering issues a request for route optimization to each boundary node, and each boundary node independently Performs an optimal route search and issues a route optimization request to each second boundary node. Each second boundary node independently performs an optimal route search, and the result is sent to each first boundary node. Each first boundary node notifies the edge node of the optimal route from each second boundary node and the optimal route of its area, and in the second step, the A route control method in which an edge node determines an optimum final route in consideration of route information of its own area.
(Supplementary note 7) In Appendix 1, there are a plurality of first boundary nodes for going from the first area to the backbone area and going from the first boundary node to the second area facing each other through the backbone area. When there are a plurality of second boundary nodes, in the first step, the edge node to perform traffic engineering issues a route optimization request to each first boundary node, and The boundary node independently performs an optimum route search and issues a route optimization request to each second boundary node. Each second boundary node independently performs an optimum route search, and the result is Arbitration is performed between the second boundary nodes, the result of the arbitration is notified to each first boundary node, and further arbitration is performed between the first boundary nodes based on the arbitration result and the optimum route of the area. And the mediation result is notified to the edge node, and in the second step, the edge node determines an optimum final route in consideration of the mediation result and route information of its own area. Route control method.
(Supplementary note 8) In supplementary note 1, in the first step, the routing information is exchanged between a node in a certain area to be traffic-engineered and each boundary node by using an OSPF Opaque LSA which is a routing protocol. Route control method characterized by
(Supplementary Note 9) In Supplementary Note 1, in the first step, the exchange of route information between a node in a certain area where the traffic engineering is to be performed and each boundary node is performed using RSVP-TE which is a signaling protocol. A route control method characterized by being performed.
(Appendix 10)
When a network is divided into a plurality of areas and managed, each area is connected via a backbone area, and the network routing control apparatus includes a plurality of boundary nodes between at least one area and the backbone area. ,
A node in an area where traffic engineering is to be performed
A first means for exchanging route information with each boundary node;
A second means for determining an optimum route based on the exchanged route information;
A path control device comprising:
(Appendix 11) In Appendix 10,
The node in the area where the traffic engineering is to be performed is an edge node, and the first means issues a route optimization request to each boundary node, and each boundary node independently performs an optimal route search, A route control apparatus that notifies the edge node of the result, and wherein the second means determines an optimum final route from among the edge node in consideration of route information of its own area.
(Appendix 12) In Appendix 10,
The node in the area where the traffic engineering is to be performed is an edge node, and the first means issues a route optimization request to each boundary node, and each boundary node independently performs an optimal route search, The result is arbitrated between the boundary nodes, the result of the arbitration is notified to the edge node, and the second means determines an optimum final route in consideration of route information of its own area. Routing device.
(Supplementary note 13) In Supplementary note 10,
When there are a plurality of boundary nodes that exist between the first area and the backbone area and are directed from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area, The first means of the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimal route search, and the result is A route control apparatus, characterized in that a first boundary node is notified, and the second means of the first boundary node determines an optimum final route in consideration of route information of its own area.
(Appendix 14) In Appendix 10,
When there are a plurality of boundary nodes that exist between the first area and the backbone area and are directed from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area, The first means of the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimum route search, and the result is sent to each first boundary node. Mediation between the two boundary nodes, notifies the first boundary node of the mediation result, and the second means of the first boundary node considers the mediation result and route information of its own area. And a route control device that determines an optimum final route.
(Supplementary note 15) In addition, there are a plurality of first boundary nodes for going from the first area to the backbone area, and going from the first boundary node to the second area facing each other through the backbone area. When there are a plurality of second boundary nodes, the first means of the edge node trying to perform traffic engineering issues a route optimization request to each boundary node, and each boundary node is optimized independently. Route search request is sent to each second boundary node, and each second boundary node independently searches for the optimum route, and the result is notified to each first boundary node. Then, each first boundary node notifies the edge node of the optimum route from each second border node and the optimum route of its area, and the second of the edge node from among them is notified. A route control device characterized in that means determines an optimum final route in consideration of route information of its own area.
(Supplementary Note 16) In Supplementary Note 10, there are a plurality of first boundary nodes for going from the first area to the backbone area, and going from the first boundary node to the second area facing each other through the backbone area. When there are a plurality of second boundary nodes, the first means of the edge node that intends to perform traffic engineering issues a route optimization request to each boundary node, and each first boundary node is independent. Then, an optimum route search is performed and a route optimization request is sent to each second boundary node, and each second boundary node independently performs an optimum route search, and the result is sent to each second boundary node. Arbitrate between nodes, notify each first boundary node of the result of the arbitration, and perform further arbitration between each first boundary node based on the arbitration result and the optimal route of their area A route control device characterized in that the mediation result is notified to the edge node, and the second means of the edge node determines an optimum final route in consideration of the mediation result and route information of its own area. .
(Supplementary Note 17) In Supplementary Note 10, the first means uses OSPF Opaque LSA, which is a routing protocol, for exchanging route information between a node in a certain area where the traffic engineering is to be performed and each boundary node. A path control device characterized by being performed.
(Supplementary note 18) In supplementary note 10, the first means uses the signaling protocol RSVP-TE to exchange route information between a node in a certain area where the traffic engineering is to be performed and each boundary node. A route control device characterized by performing.

It is principle explanatory drawing (1) of the path | route control method and apparatus concerning this invention. It is a principle explanatory view (2) of the route control method and device concerning the present invention. It is a principle explanatory view (3) of the route control method and device concerning the present invention. It is the block diagram which showed one Example of the router used for the route control method and apparatus which concerns on this invention. FIG. 5 is a block diagram showing an embodiment of a traffic engineering unit used in the router shown in FIG. FIG. 5 is a flowchart at the time of initial setting of the router shown in FIG. It is the flowchart figure which showed the operation example (1) of the path | route control method and apparatus concerning this invention. FIG. 8 is a diagram showing details of step S3 in the operation example (1) shown in FIG. FIG. 8 is a diagram showing details of step S5 in the operation example (1) shown in FIG. It is the flowchart figure which showed the operation example (2) of the path | route control method and apparatus concerning this invention. FIG. 11 is a diagram showing details of step S40 in the operation example (2) shown in FIG. It is the flowchart figure which showed the operation example (3) of the path | route control method and apparatus concerning this invention. FIG. 13 is a diagram showing details of step S13 in the operation example (3) shown in FIG. FIG. 13 is a diagram showing details of step S15 in the operation example (3) shown in FIG. It is the flowchart figure which showed the operation example (4) of the path | route control method and apparatus concerning this invention. FIG. 16 is a diagram showing details of step S140 in the operation example (4) shown in FIG. It is the flowchart figure which showed the operation example (5) of the route control method and apparatus which concern on this invention. FIG. 18 is a diagram showing details of step S28 in the operation example (5) shown in FIG. It is the flowchart figure which showed the operation example (6) of the route control method and apparatus which concern on this invention. FIG. 20 is a diagram showing details of step S280 in the operation example (6) shown in FIG. It is the figure which showed the network structural example conventionally known and which this invention makes object.

Explanation of symbols

NWa to NWd network area
Ra1 to Ra3, Rb1 to Rb6, Rc1 to Rc7, Rd1 to Rd3 Router (node)
1 NPLS router
2 IP packet forwarding unit
3 Routing protocol part
4 Normal route calculator
5 LSP management department
6 Traffic Engineering Department
7 LSP signaling section
61 Load observation section
62 Traffic Engineering (Topology) Database
63 Traffic engineering calculation part In the figure, the same reference numerals indicate the same or corresponding parts.

Claims (5)

When a network is divided into a plurality of areas and managed, each area is connected via a backbone area, and there are a plurality of boundary nodes between at least one area and the backbone area. ,
A node in an area where traffic engineering is to be performed
A first step of exchanging route information with each boundary node;
A second step of determining an optimum route based on the exchanged route information;
A path control method comprising: In claim 1,
In the first step, an edge node to perform traffic engineering issues a route optimization request to each boundary node, and each boundary node independently performs an optimum route search, and the result is obtained as the edge node. A route control method comprising: notifying a node, and determining, in the second step, an optimum final route from among the edge node in consideration of route information of its own area. In claim 1,
When there are a plurality of boundary nodes that exist between the first area and the backbone area and are directed from the first boundary node that is to perform the traffic engineering to the opposite area through the backbone area, In the first step, the first boundary node issues a route optimization request to the second boundary node, and each second boundary node independently performs an optimum route search, and the result is Route control characterized in that the first boundary node is notified, and in the second step, the first boundary node determines an optimum final route in consideration of route information of its own area. Method. 2. The second boundary node according to claim 1, wherein there are a plurality of first boundary nodes for going from the first area to the backbone area, and the second boundary node is directed from the first boundary node to the second area facing the backbone area. When there are a plurality of boundary nodes, in the first step, the edge node that intends to perform traffic engineering issues a route optimization request to each boundary node, and each boundary node independently selects an optimal route. Performing a search and issuing a route optimization request to each second boundary node, each second boundary node independently performing an optimal route search, and notifying each first boundary node of the result, Each first boundary node notifies the edge node of the optimal route from each second boundary node and the optimal route of its area, and in the second step, the edge node A route control method characterized in that a node determines an optimum final route in consideration of route information of its own area. When a network is divided into a plurality of areas and managed, each area is connected via a backbone area, and the network routing control apparatus includes a plurality of boundary nodes between at least one area and the backbone area. ,
A node in an area where traffic engineering is to be performed
A first means for exchanging route information with each boundary node;
A second means for determining an optimum route based on the exchanged route information;
A path control device comprising:

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