JP2016042670A - Communication device and transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device and a transfer method that can prevent deterioration in load balance even if actual flow distribution is different from demand at the planning time in a SPBM network that has gone through link metric optimization.SOLUTION: A communication device of the present invention includes means for selecting a transfer route so as to get close to a planned rate according to the input rate of an actual flow. This leads to increase in load balance and to improve the throughput and band utilization rate of each flow.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a communication device and a transfer method in an SPBM (Shortest Path Bridging MAC) network.

  In general, a communication device that controls data transfer in an access network collects traffic transferred from a user, multiplexes the user traffic, and then connects a core network (a large network that connects telecommunications carriers through an edge router). Forward to capacity backbone network). Each communication apparatus identifies a priority using a value such as COS described in a frame, and identifies a transmission source user using a user identifier such as a VLAN ID. In particular, redundancy of devices and paths is important from the viewpoint of improving reliability, and a layer 2 ring topology to which ERP (Ethernet (registered trademark) Ring Protection) or the like is applied has been widely used.

  On the other hand, in recent years, with the advancement of server virtualization technology in data centers, Ethernet (registration of shortest path bridging), TRILL (Transparent Interconnection of Lots of Links) such as SPB (Shortest Path Bridging) for efficient and easy management of data center networks. (Trademark) Fabric technology is being standardized. The Ethernet (registered trademark) fabric technology realizes shortest path transfer and multipath transfer by exchanging path information between nodes using IS-IS (Intermediate System to Intermediate System) to determine a transfer path. In addition, the blocking port, which has been indispensable in the past for loop avoidance, is unnecessary, and effective use of resources and easy route management are achieved.

  In the future, it is conceivable to use an Ethernet (registered trademark) fabric for a concentrator section in an access network. The blocking port is eliminated in an arbitrary network configuration, and the shortest path transfer is realized. When there are a plurality of shortest paths, multipaths are set autonomously and load distribution is executed. Therefore, effective use of resources and easy route management are expected. Furthermore, the network can be flexibly configured according to demand, not limited to the ring topology. In particular, in SPBM, which is one method in SPB, when there are a plurality of shortest paths, an end-to-end multi-path, an equivalent cost tree (ECT) is formed. At the edge node, one transfer path is selected from a plurality of transfer paths based on the service identifier (I-SID) and the like, and a relay VLAN identifier (B-VID) corresponding to the selected transfer path is given. The frame is transferred.

  In particular, there is a link metric optimization method for configuring an optimal transfer path by calculating an optimal metric value based on the demand amount and adjusting the transfer path of each flow. In this method, the traffic distribution to each ECT is also determined in order to minimize the maximum amount of traffic passing through each link. By assigning a flow to be transferred to each ECT according to the obtained traffic distribution ratio to each ECT, it is possible to perform an optimal load balance and maximize the bandwidth utilization rate.

  However, the actual flow distribution may differ from the demand at the time of planning, and in that case, there is a problem that the load balanceability is lowered. In other words, if the traffic volume obtained from the demand volume and traffic distribution is called the planned rate, optimal load balance can be achieved by performing frame transfer according to the planned rate. It is not possible to always distribute traffic accordingly.

  As a first related technique for improving the load balance in SPBM, there is a rate-based route selection method described in Non-Patent Document 1. This technology estimates the input rate for each flow at the edge node, calculates the average rate of the flow that has selected each route using this, and when a new flow arrives, selects a route with a high average rate. select. As a result, load balancing is performed while avoiding a congested route, and throughput is faired.

  As a second related technique, there is a method of optimizing the route selection probability at the edge node and improving the load balance. In this method, the expected traffic volume of each link is expressed using the path selection probability at each node as a variable, and the selection probability of each path is determined so as to minimize the maximum value. As a result, the load balance between paths can be improved, and the throughput fairness between flows can be improved.

  Although these techniques can improve the load balance in SPBM, there is a problem that load balancing cannot be performed in the entire network according to the actual flow distribution.

  For example, when the technique of Non-Patent Document 1 is used, a route that is expected to have a higher rate is always selected at each edge node, and therefore the route cannot be selected so as to approach the planned rate. In the case of using the technology of Reference 2, route selection is performed based on the route selection probability set based on the expected traffic volume in each link. Therefore, when the actual flow distribution is significantly different from the expected value, the load balanceability However, there was a problem that it could not be used to bring it closer to the planned rate.

Path selection algorithm for shortest path bridging in access networks, IEICE Communications Express, vol. 2, no. 10, pp. 396-401, 2013.

Optimization of path selection probability during ECT formation in SPBM, IEICE Technical Report, CS2013-63, pp. 19-24, December 2013

  In the related art described above, in the SPBM network in which link metric optimization is performed, the actual flow distribution may be different from the demand amount at the time of planning, and in this case, there is a problem that load balanceability is degraded.

  Therefore, an object of the present invention is to solve the above-mentioned problem, in the SPBM network in which link metric optimization is performed, even if the actual flow distribution is different from the demand amount at the time of planning, the load balanceability is reduced. To provide a communication device and a transfer method that can be prevented.

  In order to achieve the above object, the communication device and the transfer method according to the present invention perform transfer path selection so as to approach the planned rate in accordance with the actual flow input rate.

Specifically, the communication apparatus according to the present invention connects a network and the outside of the network, selects one of a plurality of transfer paths formed in the network, and transmits data received from the outside to the transfer path A communication device for forwarding to
When the data is a new flow, the amount of data transmitted per unit time to the current transfer path from the planned rate that is the amount of data transmitted per unit time preset in the transfer path And a transfer route determination unit that calculates a calculated value obtained by subtracting the actual rate and selects a transfer route having the maximum calculated value as a transfer route of the new flow.

The transfer method according to the present invention is a transfer method for transferring data introduced from outside to a network via a communication device to a destination communication device via any of a plurality of transfer paths formed in the network. And
When the data is a new flow, the amount of data transmitted per unit time to the current transfer path from the planned rate that is the amount of data transmitted per unit time preset in the transfer path And a transfer route determination procedure for calculating a calculated value obtained by subtracting the actual rate, and selecting a transfer route having the maximum calculated value as a transfer route of the new flow.

  According to the present invention, when data of a new arrival flow arrives, the actual rate of each transfer route is compared with the planned rate, and the data is transferred to a transfer route having a large margin from the actual rate to the planned rate. Therefore, the present invention can bring the actual rate close to the planned rate.

  Therefore, the present invention provides a communication apparatus and a transfer method capable of preventing a decrease in load balance even when an actual flow distribution is different from a planned demand amount in an SPBM network in which link metric optimization is performed. can do. As a result, according to the present invention, transfer paths are selected so as to approach the planned rate according to the actual flow input rate, load balanceability can be improved, and throughput and bandwidth utilization of each flow can be improved.

  When the data flow is a continuation flow that is the same as the previous data flow that arrived within a predetermined time, the transfer path determination unit of the communication device according to the present invention is the same transfer path as the transfer path of the previous data flow It is characterized by selecting.

  In the transfer route determination procedure of the transfer method according to the present invention, when the data flow is a continuous flow that is the same as the previous data flow that arrived within a predetermined time, the same transfer route as the transfer route of the previous data flow It is characterized by selecting.

  According to the present invention, by continuously selecting the same transfer path for the continuation flow, it is possible to prevent occurrence of frame order reversal or the like due to switching of the transfer path during the flow continuation.

The communication apparatus according to the present invention further includes a rate measuring unit that measures an input rate, which is a data amount received from the outside per unit time, for each flow,
The transfer path determination unit excludes a transfer path whose sum of the actual rate and the input rate exceeds a limit value set for each transfer path from the transfer destination selected for the new flow. To do.

The transfer method according to the present invention further comprises a rate measurement procedure for measuring, for each flow, an input rate, which is a data amount received from the outside per unit time,
In the transfer route determination procedure, a transfer route in which the sum of the actual rate and the input rate exceeds a limit value set for each transfer route is excluded from the transfer destination selected by the new flow. To do.

  The present invention can suppress the occurrence of congestion even when the amount of traffic is large.

  The transfer path determination unit of the communication device according to the present invention, when the sum of the actual rate and the input rate exceeds the limit value for all transfer paths, discards data received from the outside To do.

  In the transfer route determination procedure of the transfer method according to the present invention, when the sum of the actual rate and the input rate exceeds the limit value for all transfer routes, the data received from the outside is discarded. To do.

  According to the present invention, when the amount of traffic flowing into a communication device is larger than that at the time of planning, it is possible to suppress the transfer amount in the communication device and suppress the occurrence of congestion inside the SPBM network.

  The present invention provides a communication apparatus and a transfer method capable of preventing a decrease in load balance even when an actual flow distribution is different from a planned demand amount in an SPBM network in which link metric optimization is performed. Can do.

It is a figure explaining the network containing the communication apparatus which concerns on this invention. It is a block diagram explaining the structure of the communication apparatus which concerns on this invention. It is a figure explaining the transfer table which the communication apparatus which concerns on this invention has. It is a figure explaining the flow table which the communication apparatus which concerns on this invention has. It is a figure explaining the routing table which the communication apparatus concerning the present invention has. It is a figure explaining the network containing the communication apparatus which concerns on this invention. It is a figure explaining the transfer path | route selection algorithm of the communication apparatus which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not limited by the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In this specification, “rate” means the amount of data transmitted per unit time.

<Embodiment 1>
FIG. 1 is a diagram for explaining an SPBM network including a communication apparatus according to the present embodiment. In FIG. 1, a BEB (Backbone Edge Bridge) is a communication apparatus according to the present invention, and operates as an edge node in an SPBM network. BCB (Backbone Core Bridge) operates as a core node in the SPBM network. Any topology may be used in the SPBM network. A plurality of user terminals are connected to each BEB.

FIG. 2 is a diagram for explaining the configuration of the communication apparatus (BEB) of FIG. The communication device 1 is a communication device that selects any one of a plurality of transfer paths formed in the SPBM network and transfers data received from the outside to the transfer path,
When the data is a new flow, the amount of data transmitted per unit time to the current transfer path from the planned rate that is the amount of data transmitted per unit time preset in the transfer path And a transfer route determination unit 12 that calculates a calculated value obtained by subtracting the actual rate and selects a transfer route having the maximum calculated value as a transfer route of the new flow.

  The communication device 1 includes a transfer table 13, a flow table 21, and a route table 22. 3, 4, and 5 are examples of the transfer table 13, the flow table 21, and the route table 22, respectively.

  The transfer table 13 has a correspondence table of destination client MAC address (C-DA), destination BEB (B-DA), customer VID (C-VID), and service identifier (I-SID). Furthermore, it has a correspondence table of I-SID, B-VID, and output port (frame transmission unit 3). In the example of FIG. 3, B-DA (b1 / b2) corresponding to C-DA (d1 / d2) and C-VID (c1 / c2) assigned to a frame received from the outside by the frame receiving unit 2 and I-SID (s1 / s2) is described. Furthermore, B-VID (v1 / v2) corresponding to I-SID (s1 / s2) and a port (po1 / po2) of the frame transmission unit 3 are described.

The flow table 21 describes the input rate and arrival time for each frame received by the frame receiving unit 2 from the outside. In the case of a flow that has been transferred to the SPBM network in the past, the selected transfer path is also described. In the example of FIG. 4, the input rate (r ₁ / r ₂ ), the arrival time (t ₁ / t ₂ ), and the selected route (p ₁ / p ₂ ) are described for the flow (1/2). .

In the route table 22, a planned rate and an actual rate are described for each transfer route number. The planned rate is a design value or the like, and is set in advance. As will be described later, the actual rate is obtained by adding the data amount of the flow transferred through the transfer path to unit time. In the example of FIG. 5, the planned rate (P ₁ / P ₂ ) and the actual rate (R ₁ / R ₂ ) are described for the transfer path (1/2).

  For the frame (data) received by the frame receiving unit 2 from outside the SPBM network, the rate measuring unit 11 measures the input rate, the transfer path determining unit 12 refers to the transfer table 13 to determine the transfer path, and the header adding unit 14 gives a corresponding PBB (Provider Backbone Bridging) header, that is, an outer MAC header. At this time, if there is an equal cost transfer path (ECT, Equal Cost Tree), the transfer path determination unit 12 selects the transfer path. The frame with the header is transferred to another node through the frame transmission unit 3 corresponding to the destination.

  The method for adding the PBB header will be described in detail with reference to FIG. The transfer path determination unit 12 refers to the transfer table 13 and determines B-DA and I-SID based on the C-DA and C-VID of the frame. Next, when there are a plurality of B-VIDs corresponding to the I-SID, it indicates that the ECT exists, and therefore the B-VID to be given is determined based on the selection probability. In this way, after defining B-DA, I-SID, and B-VID in the PBB header, the transfer destination is determined by referring to the corresponding output port information.

  With reference to FIG. 6, it will be described that SPBM generates an end-to-end shortest path as a transfer path. In FIG. 6, BEB0, BEB1, BCB0, and BCB1 form an SPBM domain. The SPBM generates an end-to-end shortest path as a transfer path, and forms a set of transfer paths (ECT) when there are a plurality of shortest paths. When a frame arrives from outside the SPBM domain, the BEB is transferred with a B-VID corresponding to the assigned route. Here, it is assumed that CE0 connected to BEB0 transmits traffic to CE1 connected to BEB1. At this time, there are two frame transfer paths, a path 0 passing through BCB0 and a path 1 passing through BCB1.

FIG. 7 is a diagram for explaining a transfer route selection algorithm of the transfer route determination unit 12. It is assumed that the current time t is a timeout value δ. δ is a parameter and can be set by an operator. When the frame arrives at the frame receiving unit 2 (step S01), the flow number (i) of the frame is confirmed, and the input rate r _i , the frame arrival time t _i , and the selected route p _i of the flow _i are stored in the flow table 21. (Step S02). Further, the planned rate P _j and the actual rate R _j of the route _j are stored in the route table 22.

At the time of frame arrival, after updating r _i , a flow satisfying t−t _i <δ, that is, a flow in which a frame arrives within a certain time is regarded as a continuation flow, and a flow that is not so is determined as a new arrival flow (step S03).

When it is determined that the flow i is a new arrival flow (“N” in step S03), the transfer path determination unit 12 newly selects a transfer path. For the flow with p _i = j, that is, the flow for which j is selected as the transfer path, the total value of the input rates is calculated and set as R _j (step S04). Then, the transfer path determination unit 12 selects j having the maximum value of P _j -R _{j and} sets p _i = j (step S05). In other words, the transfer route determination unit 12 selects a transfer route having the largest difference between the planned rate and the actual rate from among equal-cost transfer routes.

  On the other hand, when the data flow is a continuation flow that is the same as the previous data flow that arrived within a predetermined time, the transfer route determination unit 12 selects the same transfer route as the transfer route of the previous data flow. In FIG. 7, when it is determined that the flow i is a continuation flow (“Y” in step S03), j selected when the flow i is a new arrival flow is selected, and the transfer path selected last time is selected. Continue to select. In either case, finally, the last arrival time of the frame is updated (step S06).

  By this method, when a frame of a new flow arrives, the communication apparatus 1 selects a transfer route that has the maximum difference between the planned rate and the actual rate. Therefore, route selection is performed such that the actual rate of each route approaches the planned rate. As a result, it is possible to improve load balance and improve the throughput of each flow and the bandwidth utilization rate of the entire network. Further, the communication device 1 keeps selecting the same transfer path for the continuation flow so that problems such as frame order reversal associated with switching of the transfer path during the continuation of the flow do not occur.

<Embodiment 2>
The present embodiment is substantially the same as the first embodiment except for the following points. The transfer path determination unit 12 excludes a transfer path whose sum of the actual rate and the input rate exceeds a limit value set for each transfer path from the transfer destination of the new flow. To do. In other words, the limit rate L _j for each transfer route is set in the route table 22 in advance, and the transfer route determination unit 12 calculates R _j after calculating R _j , if r _i + R _j > L _j is satisfied. Remove from the candidate and do not select the route. However, when there is no other selectable route, the transfer route determination unit 12 selects the route. With this method, the communication device 1 can suppress the occurrence of congestion even when the amount of traffic is large without transferring frames that are greater than or equal to the set value for each transfer path.

<Embodiment 3>
This embodiment is substantially the same as the second embodiment, but differs in the following points. The transfer path determination unit 12 discards data received from the outside when the sum of the actual rate and the input rate exceeds the limit value for all transfer paths. In other words, the transfer path determination unit 12 discards the frame when r _i + R _j > L _j is satisfied for all transfer paths. With this method, the communication device 1 causes the traffic volume to flow into the edge node. When there is more than the time of planning, it is possible to suppress the transfer amount in the node and suppress the occurrence of congestion in the SPBM network.

[Appendix]
The following describes the communication device of the present embodiment.
The present invention relates to a traffic control technique in a communication apparatus, and in particular, an object of the present invention is to improve transfer rate and bandwidth utilization by selecting a transfer route so as to approach a planned rate according to a flow rate.

(1):
A rate measurement unit that measures the input rate for each flow;
A flow table for storing a frame final arrival time and an input rate and a selective transfer path for each flow;
A route table that stores planned and actual rates for each route;
A route determination unit,
When a frame is received
The rate measuring unit measures the input rate of the flow and updates the flow table,
The route determination unit sets a flow in which a frame has not arrived for a predetermined time or more as a new arrival flow, and a flow in which the frame does not arrive as a continuous flow.
If the frame belongs to the new flow,
In the transfer route that can be selected according to the destination of the frame,
Select the transfer route with the maximum value obtained by subtracting the actual rate from the planned rate,
If the frame belongs to the continuous flow,
Select the previously selected transfer route,
Communication device.

(2):
The route determination unit
The frame final arrival time ti, the input rate ri, and the selective transfer path pi of the flow i are acquired from the flow table,
As the current time t and timeout value δ,
A flow that satisfies t-ti <δ is a continuation flow, a flow that is not so is a new arrival flow,
If it is determined that flow i is a new arrival flow,
For each transfer path j, the planned rate is Pj,
The total value Rj of the ri of the flow with pi = j is the actual rate,
Select the transfer path j that maximizes the value of Pj-Rj.
The communication device according to (1) above, wherein

(3):
The route determination unit
Get the limit rate Lj for each transfer route,
Do not select a transfer path that satisfies ri + Rj> Lj,
The communication device according to any one of (1) and (2) above,

(4):
The route determination unit
If ri + Rj> Lj is satisfied for all routes, the frame is discarded.
The communication device according to (3) above, wherein

  According to the present invention, the communication devices constituting the SPBM network can select the transfer route so as to approach the planned rate according to the actual flow input rate, and can improve the load balance.

1: Communication device 2 of the present invention: Frame receiving unit 3: Frame transmitting unit 11: Rate measuring unit 12: Transfer route determining unit 13: Transfer table 14: Header assigning unit 21: Flow table 22: Route table

Claims (8)

A communication device that connects a network and the outside of the network, selects any one of a plurality of transfer paths formed in the network, and transfers data received from the outside to the transfer path,
When the data is a new flow, the amount of data transmitted per unit time to the current transfer path from the planned rate that is the amount of data transmitted per unit time preset in the transfer path A communication apparatus comprising: a transfer path determination unit that calculates a calculated value obtained by subtracting the actual rate, and selects a transfer path having the maximum calculated value as a transfer path of the new flow. The transfer path determination unit
The method according to claim 1, wherein when the data flow is a continuation flow that is the same as the previous data flow that arrived within a predetermined time, the same transfer route as the previous data flow is selected. Communication device. It further includes a rate measurement unit that measures the input rate, which is the amount of data received from the outside per unit time, for each flow,
The transfer path determination unit
The transfer path in which the sum of the actual rate and the input rate exceeds a limit value set for each transfer path is excluded from the transfer destinations selected for the new flow. The communication device described. The transfer path determination unit
4. The communication apparatus according to claim 3, wherein when the sum of the actual rate and the input rate exceeds the limit value for all transfer paths, data received from outside is discarded. A transfer method for transferring data introduced into a network from outside via a communication device to a destination communication device via any of a plurality of transfer paths formed in the network,
When the data is a new flow, the amount of data transmitted per unit time to the current transfer path from the planned rate that is the amount of data transmitted per unit time preset in the transfer path A transfer method comprising: a transfer route determination procedure for calculating a calculated value obtained by subtracting the actual rate and selecting a transfer route having the maximum calculated value as a transfer route of the new flow. In the transfer route determination procedure,
6. The method according to claim 5, wherein if the data flow is a continuation flow that is the same as the previous data flow that arrived within a predetermined time, the same transfer route as the transfer route of the previous data flow is selected. Transfer method. It further includes a rate measurement procedure that measures the input rate, which is the amount of data received from the outside per unit time, for each flow.
In the transfer route determination procedure,
The transfer path in which the sum of the actual rate and the input rate exceeds a limit value set for each transfer path is excluded from the transfer destinations selected for the new flow. The transfer method described. In the transfer route determination procedure,
8. The transfer method according to claim 7, wherein when the sum of the actual rate and the input rate exceeds the limit value for all transfer paths, data received from the outside is discarded.

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