JP2008160467A - Switching hub - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching hub to promote an address learning. <P>SOLUTION: The switching hub includes an unidentified information adding means 6 to add a destination unidentified information to a frame to be transmitted by a flooding, an unidentified address registering means 7 to register a destination address of the frame as an unidentified address when the address unidentified information receives the added frame, and a priority adjusting means 8 to increase a priority of a repeating of the frame when a transmission source address of the received frame is registered as the unidentified address. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a switching hub that facilitates address learning.

  The switching hub includes a plurality of ports that transmit and receive frames, learning means that associates the source address of the frame with the port that received the frame, and a frame whose destination address has been learned is forwarded and the destination address is not yet The learning frame includes relay means for performing flooding.

  The learning means includes a forwarding database (hereinafter referred to as FDB), and the source MAC address of the received frame is registered in the FDB in association with the port that received the frame. This is called learning. The relay unit can search the FDB with the destination MAC address of the received frame to identify the port to which this frame is to be relayed, and relay, that is, forwarding only to that port.

  However, when the relay means receives a frame that has not been learned, that is, has a MAC address that is not registered in the FDB, the relay means relays, that is, floods, all the switching hubs capable of relaying. When a frame having an unlearned MAC address as a transmission source is received, learning is achieved. Thereafter, forwarding can be performed.

JP 2005-175591 A

  As shown in FIG. 6, in the switching hub 101 constituting the network called the relay network, for example, the switching hub 101A relays the frame of the destination MAC address a received from outside the relay network into the relay network. If the MAC address a is not learned, flooding is performed. The switching hub 101A continues to flood the frame of the destination MAC address a while the MAC address a is not learned. The flooded frame is received by all other switching hubs 101 and relayed into and out of the relay network.

  Since the frame is relayed to a switching hub that does not need to be relayed by flooding, if the flooding is frequent in the network, the bandwidth of the network is wasted and it is difficult to use it effectively. Therefore, it is desirable that the frequent flooding state be resolved more quickly.

  For example, when the switching hub 101B relays a frame of the source MAC address a received from outside the relay network into the relay network, the switching hub 101A that has received this frame learns the MAC address a. As a result, the switching hub 101A forwards the frame with the destination MAC address a to the switching hub 101B, so that the switching hub 101A and 101B perform unicast communication with respect to the frame with the MAC address a as the destination. , Frequent flooding is eliminated.

  However, in a system in which a server on a different network outside the relay network and a plurality of customer terminals communicate via the relay network, a switching hub is used so that some customers do not use the relay network bandwidth beyond the contracted bandwidth. In 101, band limitation may be performed. In the switching hub 101 in which band limitation is performed, a part of the received frame may be discarded without being relayed. Therefore, when the switching hub 101B performs band limitation, there is a possibility that the frame of the transmission source MAC address a is discarded by the switching hub 101B.

  If the frame of the source MAC address a is discarded and not relayed to the switching hub 101A, the switching hub 101A loses the opportunity to learn the address. Therefore, when the switching hub 101B performs band limitation, the opportunity for the switching hub 101A to learn an address is reduced. As a result, frequent flooding continues for a long time, and the bandwidth of the relay network is not effectively used.

  Therefore, an object of the present invention is to provide a switching hub that solves the above-described problems and promotes address learning.

  In order to achieve the above object, the present invention provides a plurality of ports that transmit and receive a frame, learning means that learns the source address of the frame in association with the port that received the frame, and a frame whose destination address has been learned is forwarded In a switching hub having a relay unit that performs flooding on a frame whose destination address has not yet been learned, an unknown information adding unit that adds destination unknown information to a frame transmitted by flooding, and a frame in which destination unknown information is added Priority registration to increase the priority of relaying the frame when the unknown address registration means for registering the destination address of the frame as an unknown address and the source address of the received frame are registered as an unknown address Means.

  The priority adjustment means may increase the priority in band limitation performed by the switching hub.

  The priority adjusting means may rewrite the priority information stored in the relayed frame to a higher one.

  Encapsulating means for encapsulating the frame may be provided, and the unknown information adding means may add the destination unknown information to the header of the capsule.

  The present invention exhibits the following excellent effects.

  (1) Address learning can be promoted.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the switching hub 1 according to the present invention includes a plurality of ports 2 and 3 that transmit and receive a frame, and learning means 4 that learns the frame source MAC address in association with the port that received the frame. In a switching hub provided with a relay unit 5 that performs forwarding for frames whose destination MAC address has already been learned and performs flooding for frames whose destination MAC address has not been learned, destination unknown information (hereinafter, An unknown information adding means 6 for adding a DLF (Destination Lookup Failure) mark) and an unknown address for registering the destination MAC address of the frame as an unknown address when receiving a frame to which the DLF mark as destination unknown information is added Registration means 7 and priority adjusting means 8 for increasing the relay priority of the frame when the transmission source MAC address of the received frame is registered as an unknown address.

  The learning means 4 has a transmission source MAC address search circuit for searching the FDB 9, and when receiving a frame, searches the FDB 9 with the transmission source MAC address to check whether or not the MAC address is registered. And the port are registered, and if registered, the registration is not performed.

  The relay means 5 has a destination MAC address search circuit. When a frame is received, the FDB 9 is searched with the destination MAC address to check whether or not the MAC address is registered. Forwarding to the port to be decided.

  The switching hub 1 includes band control means 10 that relays or discards received frames. Band control is control in which a frame with a higher priority has a higher probability of being relayed and a frame with a lower priority has a higher probability of being discarded. The priority level is determined by various factors such as frame capacity and customer ranking, but the determination method is not particularly limited here. It is assumed that the bandwidth control unit 10 determines the priority with reference to the priority information stored in the received frame.

  As a specific example, the bandwidth control unit 10 includes a plurality of transmission buffers prepared for each priority, an in-device priority providing unit that gives a received frame a COS (cress of service) indicating in-device information. And a sorting means for sorting the frames by COS and temporarily storing them in the corresponding transmission buffer, and a fetching means for preferentially taking out the frames from the transmission buffer having a higher priority at the transmittable timing and transferring them to the port.

  The unknown information adding means 6 is provided in association with the relay means 5, and when the flooding of the frame received by the relay means 5 is determined, a DLF mark is added to the frame.

  The unknown address registration means 7 has an unknown information check circuit that checks whether or not a DLF mark is added to the received frame. When the DLF mark is added, the destination MAC address of the frame is set to the flood address table 11. To register.

  The priority adjustment means 8 has a transmission source MAC address search circuit that searches the flood address table 11. When a frame is received, the priority adjustment unit 8 searches the flood address table 11 using the transmission source MAC address, checks whether or not it is registered, and is not registered. If it is registered, the priority is raised as follows. That is, when the bandwidth control unit 10 performs bandwidth limitation, the priority adjustment unit 8 increases the priority of a frame in which the source MAC address is registered as an unknown address, and transmits the frame from the port. The priority information stored in the frame is rewritten to a higher one.

  FIG. 1 shows one of the two or more ports of the switching hub 1, one relay network port 2 connected to the relay network shown in FIG. 2 to be described next and one access port 3 connected to the customer terminal. The figure shows only one by one. In addition, the switching hub 1 of the present invention is provided with all the well-known and commonly used configuration and function of the switching hub, but illustration and description thereof are omitted.

  As shown in FIG. 2, a plurality of switching hubs 1 (including 1A and 1B) of the present invention are installed in a relay network such as Ethernet (registered trademark). These switching hubs 1 are connected to one or more ports (for example, the relay network port 2) in the relay network, and one switching hub (not shown) or terminal (not shown) in the local network. The above ports (for example, access port 3) are connected.

  For example, a communication device such as a server serving as a multicast data distribution source is connected to the switching hub 1 in the relay network, and a customer terminal that receives the multicast data distribution is connected to another switching hub 1.

  FIG. 3 shows only the two switching hubs 1A and 1B in FIG. 2 and shows the operation of the switching hubs 1A and 1B and how frames are relayed between them.

  FIG. 4 shows which means operates in the operation of the switching hubs 1A and 1B in FIG. 3 among the means in the switching hub 1 shown in FIG.

  The operation of the switching hub of the present invention will be described with reference to FIGS.

  First, it is assumed that the frame 31 destined for the MAC address a that has not been learned is received by the access port 3 in the switching hub 1A. The relay means 5 of the switching hub 1A performs flooding because the destination MAC address a is not learned as a result of searching the FDB 9. At this time, the unknown information adding means 6 adds a DLF mark to this frame.

  When this DLF-marked frame 32 is received by the relay network port 2 of the switching hub 1B, the unknown address registration means 7 of the switching hub 1B adds the DLF mark to the DLF-marked frame 32, so that the destination MAC The address a is registered in the flood address table 11.

  Thereafter, it is assumed that the frame 33 having the MAC address a as the transmission source is received by the access port 3 in the switching hub 1B. The priority adjusting means 8 of the switching hub 1B searches the flood address table 11 to check whether it is registered. Since the MAC address a has already been registered, the priority adjustment unit 8 increases the priority of relaying the frame 33. In the bandwidth limitation of the bandwidth control means 10, the priority of the frame 33 is increased and the priority information stored in the frame 33 is rewritten to a higher one.

  Specifically, the in-device priority assigning means of the bandwidth control means 10 reads the priority (priority given to the frame) from the priority field in the VLAN tag of the frame, and information such as VID. Judge whether the frame is for a user who can receive a predetermined service from the device, whether the frame should be prioritized from the type of frame, etc., and give COS that is valid only within the switching hub to the in-device information To do.

  The sorting means of the band control means 10 sorts the frames by COS and temporarily stores them in the corresponding transmission buffer. Therefore, when frames are received one after another, they are sorted according to the COS assigned to each frame and stored in the transmission buffers according to priority.

  When it is time to transmit a frame from the port, the extraction means of the bandwidth control means 10 checks whether there is a frame waiting for transmission in order from the transmission buffer with the highest priority, and if there is a frame in the transmission buffer with the highest priority, If there is no frame in the transmission buffer with the higher priority, the frame is extracted from the transmission buffer with the next highest priority and transferred to the port.

  For example, when the switching hub 1B first receives a frame having a low priority and a transmission source MAC address b, and subsequently receives a frame having the same priority and a transmission source MAC address a, the priority adjustment means 8, since the MAC address b is not registered in the flood address table 11, a COS having a low priority is given to the first frame. However, since the MAC address a is registered in the flood address table 11, A COS having a higher priority than the frame is assigned.

  The two frames are stored in different transmission buffers according to the COS, and when the transmission is possible, the frame is extracted from the transmission buffer with the higher priority, so the frame with the source MAC address a is transmitted first. It will be.

  As a result, in the switching hub 1B, this frame 33 is preferentially relayed to the relay network. Although not shown, even if there is another switching hub between the switching hub 1B and the switching hub 1A and the bandwidth is limited, the priority information held by the frame 33 is increased. However, the frame 33 is relayed preferentially.

  When the frame 33 is received by the relay network port 2 of the switching hub 1A, the learning unit 4 of the switching hub 1A registers the transmission source MAC address a of the frame 33 in the FDB 9.

  As a result of the above operation, even when the switching hub 1B performs bandwidth limitation, the frame 33 having the transmission source of the MAC address a that has not been learned by the switching hub 1A is relayed preferentially, so the frame 33 is discarded. Is less likely. As a result, learning regarding the MAC address a in the switching hub 1A is promoted, so that a state where flooding is frequent is eliminated early. By reducing the flooding, the bandwidth of the relay network can be used effectively.

  In the switching hub 1B, if the transmission source MAC address is registered in the flood address table 11, the priority adjustment unit 8 increases the priority of relaying the frame 33, but the frame 33 is relayed immediately unconditionally. is not. For example, when the frame 33 is a frame that consumes a large amount of bandwidth, there is a problem in bandwidth limitation that relays immediately unconditionally. Therefore, it is preferable to increase the priority of relaying the frame 33 from the original priority, thereby reducing the possibility of the frame 33 being discarded while maintaining the bandwidth limit soundly, and consequently promoting learning.

  Next, an embodiment related to the DLF mark will be described.

  Here, the relay network of FIGS. 1 to 4 is a backbone bridge network. The backbone bridge network is defined by IEEE (American Institute of Electrical and Electronics Engineers) 802.1ah.

  In this relay network, since the switching hubs 1A and 1B are edge devices, the switching hubs 1A and 1B include an encapsulating unit that encapsulates a frame (referred to as a user frame for distinction) from a server or a customer terminal. Encapsulation means that the entire user frame is handled as data, and a header used in the relay network is added to the data to form an encapsulated frame.

  The unknown information adding means of the present invention adds the unknown destination information to the header when encapsulating a frame whose destination MAC address is not registered in the FDB 9.

  Specifically, as shown in FIG. 5, the encapsulated frame 51 in IEEE802.1ah includes a header 52 and data (user frame) 53. The user frame 53 includes a header and data (DATA). The header includes a destination MAC address column (DA), a source MAC address column (SA), and the like. In the header 52 of the encapsulated frame 51, each column (B-DA / B-SA) of the address of the edge device in the relay network, a column of the path control tag (B-TAG), and a column of the VNP identification tag (I-TAG) ) Is included.

  In the case of performing multicast for relaying to a plurality of edge devices, the B-DA stores an address created from a part of the DA of the user frame and the LAN-ID in the I-TAG. When performing broadcast for relaying to all edge devices, B-DA stores FF: FF: FF: FF: FF: FF of the broadcast address.

  When the edge device performs forwarding of a frame received at the access port 3, since the number of edge devices that need to be transmitted is determined, the encapsulated frame is transmitted by unicast. On the other hand, when the edge device performs flooding of the frame received at the access port 3, it is necessary to deliver the frame to all of the other edge devices, so that the encapsulated frame is transmitted by multicast or broadcast.

  When viewed from the edge device that receives the encapsulated frame, the user frame stored in the encapsulated frame received by unicast is a frame forwarded by the transmitting edge device, and the encapsulated frame received by multicast or broadcast is The stored user frame is a frame flooded in the transmitting edge device. Therefore, B-DA can play the role of destination unknown information.

  The destination unknown information may be stored anywhere in the encapsulated frame as long as it is a place where the edge device can read and write and is not used for other purposes, but is used for other purposes as in the above embodiment. Information can also be used.

It is an internal block diagram of the switching hub which shows one Embodiment of this invention. It is the conceptual diagram which showed a mode that the flame | frame was relayed between the switching hubs of this invention installed in the relay network. It is the conceptual diagram shown in more detail about two switching hubs in FIG. FIG. 3 is an internal configuration diagram of a switching hub related to internal operations of two switching hubs in FIG. 2. It is a format figure of the encapsulated frame in IEEE802.1ah. It is the conceptual diagram which showed a mode that the flame | frame was relayed between the conventional switching hubs installed in the relay network.

Explanation of symbols

1, 1A, 1B Switching hub 2 Relay network port 3 Access port 4 Learning means 5 Relay means 6 Unknown information addition means 7 Unknown address registration means 8 Priority adjustment means 9 Forwarding database (FDB)
10 Band control means 11 Flood address table

Claims (4)

  A plurality of ports that transmit and receive frames, learning means that associates the frame source address with the port that received the frame, learns, frames that have learned destination addresses are forwarded, and frames whose destination addresses have not been learned In a switching hub equipped with a relay means for performing flooding, when receiving a frame with unknown destination information added to a frame transmitted by flooding and a frame with destination unknown information added, the destination address of the frame is set. Switching comprising: an unknown address registering means for registering as an unknown address; and a priority adjusting means for increasing the priority of relaying the frame when the source address of the received frame is registered as an unknown address Hub.   2. The switching hub according to claim 1, wherein the priority adjustment means increases the priority in band limitation performed by the switching hub.   3. The switching hub according to claim 1, wherein the priority adjustment means rewrites priority information stored in a relayed frame to a higher one.    The switching hub according to claim 1, further comprising an encapsulating unit that encapsulates the frame, wherein the unknown information adding unit adds the destination unknown information to a header of a capsule.

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