JP3963308B2 - Packet repeater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packet repeater, and in particular, a packet capable of performing route control for selecting an appropriate packet transmission / reception route by expanding a spanning tree function and exchanging a route notification message with an adjacent packet repeater. It relates to repeaters.
[0002]
[Prior art]
In the IEEE802.1D document defined by IEEE (Institute of Electrical and Electronics Engineers), a bridge function related to medium access control (MAC) bridging is defined. This bridge function holds the correspondence between the source address of the received packet and the received interface as an address table, and determines the interface that transmits the received packet with reference to this address table and the destination address of the received packet. With this function, since the packet is transmitted only to the interface where the terminal that actually receives the packet exists, the use efficiency of the network can be improved as compared with the repeater hub that transmits the received packet to all the interfaces.
[0003]
Similarly, the spanning tree function is defined in the IEEE802.1D document. This spanning tree function enhances the reliability of the entire network by switching the path for transmitting and receiving packets to another path when a failure occurs in the network equipment or line in a bridge network that physically forms a loop. By exchanging configuration messages between packet relay devices, the highest priority bridge is the root, and a logical tree structure network prevents packets from falling into an infinite loop on the network. is there.
[0004]
[Problems to be solved by the invention]
The spanning tree function logically configures a tree-structured network, so when sending and receiving packets between terminals connected to bridges near the end of the tree structure, the transmission delay, path cost, etc. From an aspect, it cannot be said that an appropriate route is selected, and there are problems such as an increase in delay time required for communication, a decrease in throughput, and an increase in path cost. In particular, there is a problem that the network efficiency is remarkably lowered in a radio communication system having a large bandwidth restriction.
[0005]
The present invention solves the problems in the prior art as described above, and expands the spanning tree function and selects an appropriate packet transmission / reception route by exchanging a route notification message with an adjacent packet repeater. An object of the present invention is to provide a packet relay capable of performing path control.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the packet repeater of the present invention comprises at least two or more interfaces, holds the correspondence between the source address of the received packet and the interface that received the received packet in an address table, and the address A bridge function that determines the interface for forwarding received packets by referring to the table, and a spanning tree function that logically configures a tree-structured network by sending and receiving setup messages to and from adjacent packet relays connected by wired or wireless lines In a packet repeater having Based on the route notification message that is transmitted separately from the packet of data from the packet repeater to which the source terminal is connected and received from the packet repeater adjacent to the own packet repeater through each route Has a route optimization function to find an appropriate packet transmission / reception route The route notification message holds a type indicating that the message is a route notification message and an address to be route optimized. There is a first feature.
[0007]
Further, the present invention has a second feature in that the route optimization function obtains a route with a small number of hops of a packet repeater through which packets are transmitted and received. In addition, the present invention has a third feature in that the route optimization function obtains a route having a low total path cost when packets are transmitted and received.
[0008]
In the present invention, the route notification message may be ,further A fourth feature is that the number of hops of the packet repeater in which the route notification message is transmitted and received is held. In the present invention, the route notification message may be ,further A fifth feature is that the total path cost when the route notification message is transmitted and received is held.
[0009]
Further, the present invention is characterized in that the packet repeater that has received the route notification message holds, as the address table, the correspondence between the address held in the route notification message and the interface that has received the route notification message. There is a sixth feature.
[0010]
Further, according to the present invention, whether the correspondence between the address registered in the address table and the interface is a correspondence between the transmission source address of the received packet and the interface that has received the received packet, is held in the route notification message. The address of the received address and the interface that received the route notification message, and the address registered in the address table and the interface are stored in the route notification message. In the case of the correspondence of the interface that has received the route notification message, there is a seventh feature in that the correspondence is prioritized and the address table is not changed even if a packet is received.
[0011]
Furthermore, the present invention has an eighth feature in that the packet relay that transmits the route notification message retransmits the route notification message at a preset time interval.
[0012]
According to the first to eighth features, route control for selecting an appropriate packet transmission / reception route can be performed, and throughput and overall network efficiency can be improved.
[0013]
Further, according to the second and third features, it is possible to select an appropriate packet transmission / reception route in consideration of delay time and path cost required for communication.
[0014]
Further, according to the fourth and fifth features, it is possible to eliminate wasteful transmission of a route notification message to a route having a large number of hops or a large path cost.
[0015]
According to the seventh feature, since the address learning function performed using the route notification message is prioritized over the address learning by the normal bridge function, a broadcast packet is transmitted after route optimization is performed. Even after this, optimum route control can be performed.
[0016]
Furthermore, according to the eighth feature, since the route notification message is retransmitted, even when a loss occurs in the route notification message, optimal route control can be performed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of a network using a packet repeater according to the present invention. In FIG. 1, six packet repeaters 1 to 6 having IDs 1 to 6 are wirelessly looped. A network is configured by connecting the terminal A to the packet repeater 3 with ID No. 3 and the terminal B connected to the packet repeater 5 with ID 5 by wireless. Yes. This configuration is an example, and the number of connected packet relays and the type of communication line (wired / wireless) are not limited to this example. Further, the packet relay may be connected to a terminal or another packet relay via a LAN or a network.
[0018]
FIG. 2 is a configuration diagram showing an example of a logical network configured when the spanning tree function is applied to the network configuration of FIG. The spanning tree function prevents a packet from falling into an infinite loop on the network by configuring a network having a tree structure logically with a bridge having the highest priority as a root. In the figure, the black circle indicates the root port, and the white circle indicates the designated port.
[0019]
In FIG. 2, it is assumed that the packet relay 1 with the ID of 1 is the route with the highest priority. Each packet repeater 1 to 6 exchanges a configuration message (Configuration BPDU) holding the ID of the packet repeater 1 serving as a route, a path cost from the route, and the like between adjacent packet repeaters. The packet repeaters 2 to 6 other than the route can configure the network so that the path cost from the route is minimized by referring to the setting message.
[0020]
FIG. 3 shows an example of an address table held by the packet repeater according to the present invention. In the address table, an interface for transmitting a packet and an timer value (aging timer) are held for the address. The timer value is used to delete information related to the address from the address table when it is not specified as the source address in the received packet for the period specified by the timer value. The address is added when the packet is received, when the received interface is held for the source address of the received packet, and when the route notification message is received, it is held in the route notification message This is a case where the interface that has received the route notification message for the address is held.
[0021]
For the address table, for example, a high-speed physical memory called CAM (Conten-Addressable Memory) can be used. In addition, the correspondence between addresses and interfaces can be held by using variables, arrays, structures, etc. on the software.
[0022]
FIG. 4 shows an example of a frame format of a routing message according to the present invention. This figure shows an example in which the address to be subjected to the route optimization process and the number of hops of the packet repeater transmitted and received are notified by an Ethernet frame. A multicast address having the most significant bit of 1 is used as the transmission destination address of this frame. Each packet relay stores its own address as a source address when transmitting a packet. In addition, by using a specific number indicating a routing message as a type, the packet relay can identify that the received message is a routing message. The number of hops is, for example, a value obtained by adding 1 each time the number of packet relays to be relayed increases by 1 when the number of hops of the packet relay that first transmits a route control message is 1. Is done.
[0023]
FIG. 5 is a flowchart showing an example of processing in each packet relay when receiving a routing control message according to the present invention, and this processing flow includes the following steps S1 to S4.
S1: Add 1 to the number of hops held in the received routing message.
S2: The correspondence between the source address held in the routing message and the interface that received the routing message is held in the address table.
S3: Determine the number of hops. If the number of hops is smaller than a predetermined threshold, the process proceeds to step S4. If the number of hops is greater than or equal to the threshold, the process is terminated. As the threshold value, for example, a value that is ½ of the total number of packet repeaters constituting the network (rounded down to the nearest decimal point) or smaller is used.
S4: A route notification message is transmitted from an interface other than the interface that received the route notification message.
[0024]
FIG. 5 is an example of determining the number of hops after recalculating the number of hops. However, the number of hops is determined using a threshold smaller by one than in the example of FIG. When the number is small, recalculation of the number of hops and transmission of a routing message may be performed.
[0025]
FIG. 6 is a flowchart showing an example of a communication sequence by the packet repeater of the present invention. In the figure, it is assumed that the terminals A and B communicate after the network having the logical tree structure shown in FIG. 2 is configured by the spanning tree function. Numbers 1 to 6 indicate packet repeaters.
[0026]
First, the terminal A transmits a packet to the terminal B (S11). The packet relay 3 that has received the packet transmitted from the terminal A refers to the transmission destination address (the address of the terminal B) of the received packet and searches whether the address is held in the address table. If the transmission destination address (terminal B address) is held in the address table, the packet is transmitted from the interface corresponding to the address. If the transmission destination address (terminal B address) is not held in the address table, the packet is transmitted from all interfaces other than the received interface.
[0027]
Here, assuming that the transmission destination address (address of terminal B) is held in the address table of the packet relays 1 to 6, the packet relay 3 that has received the packet transmitted from the terminal A has the address table The packet is transmitted from the interface connected to the adjacent packet relay 2 with reference to (S12). At the same time, the packet relay 3 holds the correspondence between the source address of the received packet (the address of the terminal A) and the interface that has received the packet in the address table (S13).
[0028]
The packet relay 2 that has received the packet transmitted from the packet relay 3 transmits the packet from the interface connected to the adjacent packet relay 1 with reference to the address table (S14), and the source of the received packet The correspondence between the address (the address of terminal A) and the interface that received the packet is held in the address table (S15).
[0029]
Similarly, the packet relay 1, the packet relay 6, and the packet relay 5 transmit and receive packets, and the correspondence between the transmission source address of the received packet (the address of the terminal A) and the interface that has received the packet is an address table. (S16 to S21). Finally, the terminal B receives the packet transmitted from the packet relay 5 (S20).
[0030]
Further, the packet relay 3 that has transmitted the packet transmits a route notification message from the interface connected to the adjacent packet relays 2 and 4 (S22). As shown in FIG. 4, this route notification message holds the address to be subjected to route optimization processing and the number of hops of the packet repeater transmitted and received. The target address held in the route notification message in S22 is the address of terminal A, and the hop count is 1. In addition, the packet relays 2 and 4 that have received the route notification message from the packet relay 3 add 1 to the number of hops to 2, and the target address held in the route notification message, that is, the address of the terminal A The correspondence with the interface that has received the route notification message is held in the address table (S23, S24), and the route notification message is transmitted to the adjacent packet relays 1, 5 (S25, S26).
[0031]
Similarly, the packet relays 1 and 5 that have received the route notification message hold the correspondence between the target address held in the route notification message and the interface that has received the route notification message in the address table (S27, S28). Here, in the packet relay 5, the interface associated with the address of the terminal A is changed from the interface connected to the packet relay 6 to the interface connected to the packet relay 4. Also, assuming that 3 is set as the threshold value in S3 of FIG. 5, the packet relay device 1 and the packet relay device 5 add 1 to the number of hops to 3, which is equal to or greater than the threshold value 3. The route notification message is not transmitted.
[0032]
By referring to the address table held in each packet repeater by the route optimization process from S22 to S28, the packet transmitted from the terminal B sequentially passes through the packet repeater 5, the packet repeater 4, and the packet repeater 3. The terminal A is reached through the optimum route to be relayed (S29 to S32). That is, a route with a small number of hops of the packet repeater is obtained by route optimization processing and held as an address table, and a packet is transmitted through the route.
[0033]
As described above, when the threshold value in S3 of FIG. 5 is, for example, ½ of the total number of packet repeaters constituting the network (truncated after the decimal point) or a smaller value, a plurality of packet repeaters are used. No route notification message is received, and unnecessary transmission of the route notification message can be eliminated. Also, depending on the threshold setting, there may be a packet repeater that does not receive the route notification message. In this case, the packet repeater can send packets to the root side by the spanning tree function. That's fine.
[0034]
FIG. 7 shows another example of an address table held by the packet repeater according to the present invention. In the example of the figure, the correspondence between the address registered in the address table and the interface is the correspondence between the source address of the received packet and the interface that received the received packet, or the target address held in the route notification message and A flag is held in the address table in order to identify whether it corresponds to the interface that has received the route notification message. In this example, if the correspondence between the address registered in the address table and the interface is the correspondence between the source address of the received packet and the interface that received the received packet, the flag is set to 0 and is held in the route notification message. The flag is set to 1 if the address corresponds to the interface that received the route notification message. This flag can be held by adding it together with the corresponding interface information when adding the address information to the address table.
[0035]
FIG. 8 shows still another example of the address table held by the packet relay according to the present invention. In the example of the figure, the correspondence between the address registered in the address table and the interface is the correspondence between the source address of the received packet and the interface that received the received packet, or the target address held in the route notification message and In order to identify the correspondence with the interface that has received the route notification message, information on the number of hops is held in the address table. In this example, if the correspondence between the address registered in the address table and the interface is the correspondence between the source address of the received packet and the interface that received the received packet, the hop count is set to 0 and held in the route notification message. In the case of correspondence between the received address and the interface that has received the route notification message, the hop number of the packet relay that has transmitted and received the route notification message is held. The number of hops can be held by adding together with the corresponding interface information when adding the address information to the address table.
[0036]
FIG. 9 is a flowchart showing another example of a communication sequence by the packet repeater of the present invention. The figure shows an example in which terminal A transmits a broadcast packet after route optimization processing related to the address of terminal A is performed. In this example, the following description will be made assuming that the address table of FIG. 7 or FIG. 8 is used.
[0037]
First, the terminal A transmits a packet to the terminal B (S41). The packet relay 3 that has received the packet transmitted from the terminal A refers to the transmission destination address (the address of the terminal B) of the received packet and searches whether the address is held in the address table. If the transmission destination address (terminal B address) is held in the address table, the packet is transmitted from the interface corresponding to the address. If the transmission destination address (terminal B address) is not held in the address table, the packet is transmitted from all interfaces other than the received interface.
[0038]
Here, assuming that the transmission destination address (address of terminal B) is held in the address table of the packet relays 1 to 6, the packet relay 3 that has received the packet transmitted from the terminal A has the address table The packet is transmitted from the interface connected to the adjacent packet relay 2 with reference to (S42). At the same time, the packet relay 3 holds the correspondence between the transmission source address of the received packet (the address of the terminal A) and the interface that has received the packet, and the flag 0 or the hop number 0 in the address address table (S43).
[0039]
The packet relay 2 that has received the packet transmitted from the packet relay 3 transmits the packet from the interface connected to the adjacent packet relay 1 with reference to the address table (S44), and the source of the received packet The correspondence between the address (the address of terminal A) and the interface that has received the packet, and flag 0 or hop number 0 are held in the address table (S45).
[0040]
Similarly, the packet repeater 1, the packet repeater 6, and the packet repeater 5 transmit and receive packets, and correspond to the source address of the received packet (the address of the terminal A) and the interface that received the packet, and the flag 0 or 0 is held (S46 to S51). Finally, the terminal B receives the packet transmitted from the packet relay 5 (S50).
[0041]
Further, the packet relay 3 that has transmitted the packet transmits a route notification message from the interface connected to the adjacent packet relays 2 and 4 (S52). As shown in FIG. 4, this route notification message holds the address to be subjected to route optimization processing and the number of hops of the packet repeater transmitted and received. The address held in the route notification message in S52 is the address of terminal A, and the hop count is one. In addition, the packet relays 2 and 4 that have received the route notification message from the packet relay 3 add 1 to the number of hops to 2, and the interface that has received the route notification message and the address held in the route notification message And the flag 1 or the number of hops 2 are held in the address table (S53, S54), and a route notification message is transmitted to the adjacent packet relays 1, 5 (S55, S56).
[0042]
Similarly, the packet relays 1 and 5 that have received the route notification message hold in the address table the correspondence between the address held in the route notification message and the interface that received the route notification message, and the flag 1 or hop number 3. (S57, S58). Here, in the packet relay 5, the interface associated with the terminal A is changed from the interface connected to the packet relay 6 to the interface connected to the packet relay 4. Also, assuming that 3 is set as the threshold value in S3 of FIG. 5, the packet relay device 1 and the packet relay device 5 add 1 to the number of hops to 3, which is equal to or greater than the threshold value 3. The route notification message is not transmitted.
[0043]
Furthermore, after the route optimization process from S52 to S58, the terminal A transmits a broadcast packet (S59). The broadcast packet is transmitted to the entire network (S60 to S64). In S63, the interface on which the packet relay 5 has received the broadcast packet is an interface connected to the packet relay 6, and is different from the interface with which the terminal A is associated in the address table. However, since the flag 1 or the hop number 3 is set in the address table, the address table is not corrected. Thus, the address learning function performed using the route notification message by referring to the flag or the number of hops is prioritized over the address learning by the normal bridge function.
[0044]
Even when the terminal A transmits a broadcast packet after the route optimization processing from S52 to S58 (S59 to S64), the packet transmitted from the terminal B is not transmitted to the packet relay 5, the packet relay 4, and the packet relay. 3 reaches the terminal A through the optimum route for sequentially relaying 3 (S65 to S68).
[0045]
FIG. 10 is a flowchart showing still another example of a communication sequence by the packet repeater of the present invention. This figure shows an example in which a loss occurs in the route control message due to a bit error in the communication line.
[0046]
First, terminal A transmits a packet to terminal B (S71). The packet relay 3 that has received the packet transmitted from the terminal A refers to the transmission destination address (the address of the terminal B) of the received packet and searches whether the address is held in the address table. If the transmission destination address (terminal B address) is held in the address table, the packet is transmitted from the interface corresponding to the address. If the transmission destination address (terminal B address) is not held in the address table, the packet is transmitted from all interfaces other than the received interface.
[0047]
Here, assuming that the transmission destination address (address of terminal B) is held in the address table of the packet relays 1 to 6, the packet relay 3 that has received the packet transmitted from the terminal A has the address table The packet is transmitted from the interface connected to the adjacent packet relay 2 with reference to (S72). At the same time, the packet relay 3 holds the correspondence between the source address of the received packet (the address of the terminal A) and the interface that has received the packet in the address table (S73).
[0048]
The packet relay 2 that has received the packet transmitted from the packet relay 3 transmits the packet from the interface connected to the adjacent packet relay 1 with reference to the address table (S74), and the source of the received packet The correspondence between the address (the address of terminal A) and the interface that received the packet is held in the address table (S75).
[0049]
Similarly, the packet relay 1, the packet relay 6, and the packet relay 5 transmit and receive packets, and the correspondence between the transmission source address of the received packet (the address of the terminal A) and the interface that has received the packet is an address table. (S76 to S81). Finally, the terminal B receives the packet transmitted from the packet relay 5 (S80).
[0050]
Further, the packet relay 3 that has transmitted the packet transmits a route notification message from the interface connected to the adjacent packet relays 2 and 4 (S82). As shown in FIG. 4, this route notification message holds the address to be subjected to route optimization processing and the number of hops of the packet repeater transmitted and received. In S82, the address held in the route notification message is the address of terminal A, and the number of hops is one. Here, it is assumed that a loss has occurred in the route notification message transmitted from the interface connected to the packet relay 2 among the route notification messages transmitted by the packet relay 3 due to a bit error or the like. Therefore, only the packet relay 4 receives the route notification message, adds 1 to the number of hops to 2, and sets the correspondence between the address held in the route notification message and the interface that received the route notification message in the address table. In addition, the route notification message is transmitted to the adjacent packet relay 5 (S84).
[0051]
Similarly, the packet relay 5 that has received the route notification message holds the correspondence between the address held in the route notification message and the interface that has received the route notification message in the address table (S85).
[0052]
The packet relay 3 that has transmitted the route notification message retransmits the route notification message at a preset time interval (S86). Thereby, the packet relay 2 and the packet relay 1 that could not receive the route notification message transmitted first can receive the route notification message, and have received the address and the route notification message held in the route notification message. The correspondence with the interface can be held in the address table (S87 to S89).
[0053]
Even if a loss occurs in the route notification message due to the retransmission processing of the route notification message from S86 to S90, the packet transmitted from the terminal B is sequentially relayed through the packet relay 5, the packet relay 4, and the packet relay 3. The terminal A is reached through the optimum route (S91 to S94).
[0054]
The above-described embodiment is merely an example, and the present invention is not limited to this. For example, instead of holding the number of hops in the route control message, or in addition to that, the accumulated value of the path cost determined from each port when the route notification message is transmitted and received is held as the total path cost. By transmitting a route notification message within the path cost threshold and updating the address table, it becomes possible to select a route in consideration of the total path cost. Those skilled in the art can easily make various changes, modifications, and omissions within the scope of the technical idea of the present invention, and these are also included in the technical scope of the present invention. The invention is limited only as defined in the following claims and the equivalents thereto.
[0055]
【The invention's effect】
As described above in detail, according to the present invention, the spanning tree function is expanded, and a route for selecting an appropriate route even when terminals connected to a bridge near the end of the tree structure communicate with each other. Control can be performed. Thereby, the delay time required for communication can be reduced, the throughput can be improved, and the efficiency of the entire network can be improved. In particular, the effect is significant when applied to a wireless communication system with a large bandwidth restriction.
[0056]
In addition, by giving priority to the address learning function performed using the route notification message over the address learning by the normal bridge function, an appropriate route can be obtained even after a broadcast packet is transmitted after route optimization is performed. Control can be performed.
[0057]
Furthermore, by retransmitting the route notification message, appropriate route control can be performed even if a loss occurs in the route notification message.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a network using a packet repeater according to the present invention.
2 is a configuration diagram illustrating an example of a logical network configured when a spanning tree function is applied to the network configuration of FIG. 1;
FIG. 3 is an explanatory diagram of an example of an address table held by the packet relay according to the present invention.
FIG. 4 is an explanatory diagram illustrating an example of a frame format of a routing message according to the present invention.
FIG. 5 is a flowchart showing an example of processing in each packet relay when receiving a routing message according to the present invention.
FIG. 6 is a flowchart showing an example of a communication sequence by the packet repeater of the present invention.
FIG. 7 is another example of an address table held by the packet relay according to the present invention.
FIG. 8 is still another example of an address table held by the packet relay according to the present invention.
FIG. 9 is a flowchart showing another example of a communication sequence by the packet repeater of the present invention.
FIG. 10 is a flowchart showing still another example of a communication sequence by the packet repeater of the present invention.
[Explanation of symbols]
1, 2, 3, 4, 5, 6 ... packet repeater, 11 ... end A, 12 ... terminal B

Claims (8)

A bridge function that includes at least two or more interfaces, holds a correspondence between a transmission source address of a received packet and an interface that has received the received packet in an address table, and determines an interface to which the received packet is transferred with reference to the address table And a packet repeater having a spanning tree function for transmitting and receiving a setting message with an adjacent packet repeater connected by a wired or wireless line and logically constructing a tree-structured network,
An appropriate packet transmission / reception route is transmitted based on a route notification message that is transmitted separately from the packet of data from the packet repeater to which the source terminal is connected and received from the packet repeater adjacent to the own packet repeater through each route. have a route optimization function of obtaining,
The packet relay device characterized in that the route notification message holds a type indicating that the message is a route notification message and an address to be subjected to route optimization . The packet repeater according to claim 1, wherein the route optimization function obtains a route with a small number of hops of a packet repeater through which packets are transmitted and received. The packet repeater according to claim 1, wherein the route optimization function obtains a route having a small total path cost when a packet is transmitted and received. The route notification message further packet repeater according to claim 2 in which said path notification message, characterized in that for holding the number of hops of the packet repeater is transmitted and received. The packet repeater according to claim 3, wherein the route notification message further holds a total path cost when the route notification message is transmitted and received. The packet relay that receives the route notification message holds the correspondence between the address held in the route notification message and the interface that has received the route notification message as the address table. The packet repeater according to any one of 1 to 5. Whether the correspondence between the address registered in the address table and the interface is the correspondence between the source address of the received packet and the interface that received the received packet, or the address held in the route notification message and the route notification A hand throw that identifies whether the interface is the correspondence of the interface that received the message, and the correspondence between the address registered in the address table and the interface is stored in the route notification message and the route notification message is received. 7. The packet repeater according to claim 6, wherein when the interface is compatible, priority is given to the correspondence and the address table is not changed even if a packet is received. The packet relay according to claim 1, wherein the packet relay that transmits the route notification message retransmits the route notification message at a preset time interval.

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