JP2006087014A - Layer-2 switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assign a queue to a multicast frame of a transfer target only while transfer setting is performed in a layer-2 switch. <P>SOLUTION: The layer-2 switch comprises a control unit, a classifier and a scheduler. The control unit determines a port of a switch unit that performs layer-2 switching among a plurality of ports according to a setting instruction, to which a transfer target multicast frame is to be transferred, based on a multicast address of message contents for multicast control obtained by snooping a multicast control frame flowing in the switch unit and transmission source port information to which this message is delivered, instructs setting of switch path to the switch unit, determines, sets and instructs at least one queue for temporarily storing the multicast frame and QoS of that queue. The classifier and the scheduler operate according to setting instructions from the control unit. If the cancel of transfer setting of the multicast frame is recognized based on the snooped information, the control unit requests the cancel of setting to the respective units. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a layer 2 switch for connecting between routers and routers in an IP (Internet Protocol) network or between a router and a host (a host computer which is a local area network (LAN) accommodating terminal), and in particular, a multicast frame in a packet form. The present invention relates to a layer 2 switch having a QoS (Quality of Service) setting function for transfer.

  In the IP network, the layer 2 switch forwards, ie, floods, a multicast frame in the form of a packet to all the remaining ports (egress ports) in the same segment other than the ingress port in the same manner as the broadcast frame. At this time, if this frame is transferred to a port to which a router or host that wishes to receive the multicast frame is not connected, the bandwidth (transmission band) is wasted (used) by the unnecessary multicast frame at that port. I can't escape.

In order to avoid this problem, in the layer 2 switch, PIM-DM (Protocol Independent Multicast-Dense Mode), PIM-SM exchanged between routers and routers.
(Snooping) the contents of multicast control protocols (routing protocols) such as (Protocol Independent Multicast-Sparse Mode), PIM-SSM (Protocol Independent Multicast-Source Specific Multicast), or DVMRP (Distance Vector Multicast Routing Protocol) By snooping the contents of multicast control protocols such as IGMP (Internet Group Management Protocol) or MLD (Multicast Listener Discovery) between the router and host, the port to which the multicast frame in packet form is to be transferred is determined. is doing.

  However, the conventional layer 2 switch only controls whether or not to forward the multicast group frame to the port based on the snooping result. For this reason, when a multicast frame is transferred to a port, it is handled in the same way as a normal unicast frame in priority and bandwidth. Multicast frames are often used for specific purposes. However, when setting QoS such as priority and bandwidth on a port, it is necessary to set it manually (command input) in advance for each port.

When QoS is controlled, a dedicated queue is fixedly allocated for a multicast frame to be transferred, so that the queue reservation state is continued even when the multicast frame is not flowing, and the number of queues is consumed. Furthermore, when a bandwidth is fixedly allocated to the queue and used exclusively with other traffic, the bandwidth is wasted during a time when no multicast frame is flowing.
JP 2004-80523 A

  An object of the present invention is to make it possible to assign a queue to a multicast frame to be transferred only when there is a multicast frame transfer request from the router or host to the layer 2 switch and the forwarding setting is made in the layer 2 switch. Is to provide.

In order to solve the above problems, the layer 2 switch of the present invention is a layer 2 switch that transfers a multicast frame in a packet form only to a necessary port connected to a router or a host by snooping a multicast control frame. There;
A switch unit that performs layer 2 switching between a plurality of ports in accordance with a setting instruction;
Based on the multicast address of the multicast control message content obtained by snooping the multicast control frame flowing through this switch unit, and the port of the switch unit to which the multicast frame to be transferred is to be transferred based on the source port information to which this message has arrived A control unit for instructing the switch unit to set a switch path and determining and instructing to set at least one queue for temporarily storing the multicast frame to be transferred and the QoS of the queue;
A classifier that inputs the multicast frame to be transferred to a predetermined queue in accordance with a setting instruction from the control unit;
A scheduler that sets QoS of the predetermined queue in accordance with a setting instruction from the control unit;
When the control unit recognizes the cancellation of the multicast frame transfer setting based on the snooping information, the control unit requests the switch unit, the classifier, and the scheduler to cancel the setting. Layer 2 switch.

  In this configuration, the control unit stores, in the first list, information including a use queue for a multicast address set in advance or dynamically by an operator and QoS of the use queue, and information on the first list. The multicast address and its allocation queue are instructed to the classifier corresponding to the port to which the multicast frame to be forwarded is to be forwarded, and the scheduler corresponding to the port to be forwarded is queued. Instructs QoS setting.

  Further, the control unit reads the multicast address in the multicast control message when the multicast control message and the source port information to which the message has arrived are transferred from the switch unit as snooping information, Write to the second list along with the source port information.

  Furthermore, after the writing to the second list, the control unit compares the multicast address in the second list with the multicast address in the first list, and if both multicast addresses match It is possible to read use queue information and QoS setting information from the first list and make a setting request to the classifier and scheduler corresponding to the source port to which the multicast control message has arrived.

  According to the present invention, in the layer 2 switch, it is possible to control to assign a queue to a multicast frame only when the multicast frame flows. With this control, even if you want to perform QoS control that allocates a fixed band for a multicast frame and does not use that band for other traffic, no band is allocated in the time when there is no transfer of the multicast frame. Bandwidth when multicast frames are not transferred can be used effectively.

In addition, in the actual use of the multicast frame, it is assumed that broadcast type video streaming is used. In this case, one multicast address is assigned to one channel, and many multicast addresses are layer 2 Transfer or stop is set on the switch. Here, when QoS is to be set, there is no bandwidth limitation when a bandwidth is allocated to a queue by the round robin method, but in a method in which a queue is fixedly allocated to each address, a finite number of queues are set. Is likely to run out. Further, the configuration in which the entire multicast address is set in one queue cannot cope with a case where a plurality of multicast frames are transferred at the same time or when it is desired to change the bandwidth for each address.

  On the other hand, when the present invention is applied, not only can a large number of channels be handled with a small number of queues, but also a band can be set for each channel.

  Other objects, features and advantages of the present invention will become apparent upon reading the specification set forth below when taken in conjunction with the drawings and the appended claims.

  Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The drawings show preferred embodiments of the invention. However, the invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[Constitution]
(IP network system)
Referring to FIG. 1 showing the configuration of an IP network system SYS to which the layer 2 switch SW according to an embodiment of the present invention is applied, the IP network system SYS is generated by one of a plurality of multicast servers SV. The multicast packet is transmitted to a plurality of hosts (host computers) HT that are LAN accommodating terminals.

  When the layer 2 switch SW determines a distribution destination and distribution route of a multicast packet (multicast frame), a multicast control protocol such as PIM-DM, PIM-SM, PIM-SSM, or DVMRP is used between the router RT and the router RT. The router RT or host HT to which multicast packets are to be transferred is determined by using a multicast control protocol such as IGMP or MLD between the router RT and the host HT. In this embodiment, a frame in packet form that is transferred (including transmission) in accordance with these multicast control protocols is referred to as a multicast control frame.

  The layer 2 switch SW located between the router RT and the router RT or between the router RT and the host HT snoops a multicast control frame for determining a distribution destination and a distribution route to the router RT or the host HT, thereby necessary ports ( A multicast frame in the form of a packet is transferred only to an outgoing port or a outgoing port.

(Layer 2 switch)
FIG. 2 shows a configuration example of the layer 2 switch SW in FIG. In the layer 2 switch SW, the multicast traffic control unit 10 is based on the multicast control protocol message and source (sender) port information obtained by snooping the multicast control frame flowing through the internal switch (switch unit) 20. The queue (# 1 to #n) 30 for inputting (temporarily storing) the multicast frame and the QoS setting of the queue 30 are determined, and setting instructions are given to the classifier 40 and the scheduler 50, respectively.

The classifier 40 inputs a multicast frame to be transferred to a predetermined queue 30 in accordance with setting information (setting instruction) from the multicast traffic control unit 10. The scheduler 50 sets QoS such as the bandwidth and priority of the queue 30 in accordance with the setting information from the multicast traffic control unit 10.

  When the multicast traffic control unit 10 recognizes cancellation of the multicast frame transfer setting based on the snooping information, the multicast traffic control unit 10 requests the classifier 40 and the scheduler 50 to cancel the setting and returns the classifier 40 and the scheduler 50 to the initial state.

  In the layer 2 switch SW, this function enables the router RT or the host HT to request the transfer of the multicast frame and assign the queue 30 to the multicast frame to be transferred only while the transfer is set.

  More specifically, the internal switch 20 in the layer 2 switch SW has a plurality of ports (# 1 to #n) 21 corresponding to the plurality of interface units (# 1 to #n) 60, and a layer between the ports 21. 2 Switching is performed. When the multicast control frame passes through the inside of the switch, the internal switch 20 copies the frame and transfers it to the multicast traffic control unit 10 together with information (source port number) indicating which port 21 has received the frame. Have

  Further, the internal switch 20 has a function of transferring the multicast frame only to the port 21 corresponding to the setting instruction in accordance with the setting instruction (destination MAC (Media Access Control) address of the multicast frame and its transfer port) from the multicast traffic control unit 10. Have.

  Based on the message contents of the multicast control frame transferred from the internal switch 20 and the information of the receiving port (source port information), the multicast traffic control unit 10 is to transfer the multicast frame designated by the message (Egress port or transmission port) 21 is determined and the internal switch 20 is instructed to set a transfer route (switch path).

  In addition, the multicast traffic control unit 10 applies the multicast traffic to the classifier 40 corresponding to the port 21 based on a setting list including a use queue, a bandwidth, and a priority for a multicast address set in advance or dynamically by an operator. The setting of the address and its allocation queue 30 is instructed, and the QoS setting (scheduling setting) of the queue 30 is instructed to the scheduler 50 corresponding to the port 21. Here, when an operator inputs a setting list from an operation terminal such as a personal computer to the multicast traffic control unit 10 via the dedicated port 70 of the layer 2 switch SW, the dedicated port 70 is transmitted through a network communication line (transmission path). Or directly from the operation terminal to the dedicated port 70.

  Each classifier 40 is provided corresponding to each of the plurality of ports (# 1 to #n) 21 of the internal switch 20, and the transmission side (output port) of each port 21 and the plurality of queues 30 corresponding to each classifier 40. And connected to. Each classifier 40 stores the transmission frame from the port 21 of the internal switch 20 based on the definition information (corresponding list of the frame condition (multicast address) and the queue 30 for transferring the frame) held internally (stored). It is divided into QoS classes and transferred to the corresponding queue 30. Further, the classifier 40 updates this definition information in accordance with the setting instruction from the multicast traffic control unit 10.

  A plurality of queues (# 1 to n) 30 corresponding to each classifier 40 are respectively connected to the classifier 40 and the scheduler 50, and temporarily store a multicast frame to be transferred.

  Each scheduler 50 is provided corresponding to each port 21 of the internal switch 20, and is connected to the plurality of queues 30 and the transmission side of each interface unit 60. Each scheduler 50 reads out frames in order from a plurality of queues 30 and transfers them to the corresponding interface unit 60, or controls the order of reading from the queues 30, thereby performing bandwidth control and priority control in units of each queue 30. Do.

  That is, for example, the bandwidth of the communication line of the network connected to the interface unit 60 is 100 Mbps / max. When the bandwidth of 20 Mbps (fixed bandwidth) is set in the first queue (# 1) 30 and the bandwidth of 10 Mbps (fixed bandwidth) is set in the second queue (# 2) 30, the scheduler 50 The multicast frame is read from the first queue (# 1) 30 once every five reading cycles and from the second queue (# 2) 30 once every ten reading cycles. Control. Each scheduler 50 has a function of changing the bandwidth and priority of the queue 30 in accordance with a setting instruction from the multicast traffic control unit 10.

  Each interface unit 60 terminates layer 1 in connection with another device (router RT or host HT). Each interface unit 60 transfers a reception frame from another device to the reception side (reception port) of the port 21 in the corresponding internal switch 20, and transmits a transmission frame from the corresponding scheduler 50 to the other device.

(Multicast traffic controller)
FIG. 3 shows details of information held by the multicast traffic control unit 10 in FIG. The multicast traffic control unit 10 holds a setting list 11 that associates with which queue 30 a multicast frame corresponding to a designated multicast address or a range of multicast addresses input by an operator is to be placed.

  When the frame including the multicast control message (for setting) and the information of the port (the source port information) from which this message has arrived are transferred from the internal switch 20 as the snooping information, the multicast traffic control unit 10 The multicast address is read out and written in the snooping result list 12 together with the source port information.

  After writing to the snooping result list 12, the multicast traffic control unit 10 compares the multicast address in the snooping result list 12 with the multicast address in the setting list 11, and if they match, the setting list 11 To read the number (# 1 to #n) of the queue 30 to be used and the QoS setting information of the bandwidth and priority.

  Subsequently, the multicast traffic control unit 10 creates a setting request message for the classifier 40 (including information on the address and the queue 30 to be used) and a setting request message for the scheduler 50 (including information on the queue number and scheduling method). Then, a setting request is sent to the classifier 40 and scheduler 50 corresponding to the port 21 to which the multicast control message (for setting) has arrived.

The multicast traffic control unit 10 uses the following two methods (A) and (B) according to the type of multicast control protocol when the transfer is canceled.
(A) Cancellation by setting cancellation request from host When the multicast traffic control unit 10 transfers a multicast control message (for cancellation) and port information (source port information) from which this message has arrived, The multicast address in this message is read and compared with the contents of the snooping result list 12. As a result of the comparison, if the multicast address exists in the snooping result list 12, the multicast address is deleted from the snooping result list 12.

The multicast traffic control unit 10 deletes the multicast address from the snooping result list 12 and then compares the multicast address with the contents of the setting list 11. If the two match, the multicast traffic control unit 10 creates a setting cancellation request message (including address information) for the classifier 40 and a setting cancellation request message (including the queue information to be used) for the scheduler 50, A setting cancellation request is made to the classifier 40 and scheduler 50 corresponding to the port 21 to which the multicast control message (for cancellation) has arrived.
(B) Release by keep-alive information from the router When the multicast frame is transferred, the router RT periodically transmits a multicast control message (keep-alive) to the host HT. When the host HT stops responding to this message, the router RT stops the multicast frame transfer setting. When receiving the multicast control message (keep alive) from the internal switch 20, the multicast traffic control unit 10 reads the multicast address in the message and compares it with the contents of the snooping result list 12.

  As a result of the comparison, if the multicast address exists in the snooping result list 12, the timer 13 is started. The multicast traffic control unit 10 deletes the multicast address from the snooping result list 12 when there is no keep-alive response from the host HT within the time determined by the protocol of the multicast control protocol.

  After deleting the multicast address from the snooping result list 12, the multicast traffic control unit 10 compares the multicast address with the multicast address in the setting list 11, and if they match, the setting release request message to the classifier 40 (Including address information) and a setting cancellation request message (including queue information to be used) to the scheduler 50 are created, and a multicast control message (for cancellation) arrives, that is, there is no keepalive response. A setting cancellation request is made to the classifier 40 and the scheduler 50.

[Operation]
Next, various operation examples in the layer 2 switch SW according to the embodiment of the present invention shown in FIGS. 1, 2 and 3 will be described.

(Setting operation when snooping IGMP)
FIG. 4 shows only the configuration of the main part necessary for the description of the setting operation in the layer 2 switch SW according to the embodiment of the present invention whose detailed configuration is shown in FIG.

  Here, the router RT is connected to the interface unit 60 (not shown) corresponding to the first port (# 1) 21 in the internal switch 20 via the network communication line, and the second port (# 2) 21 is connected. Similarly, the host HT is connected to the interface unit 60 (not shown) corresponding to the above.

When the layer 2 switch SW performs a normal IGMP snooping function, in the initial state, since the identification is performed based on the MAC address, a frame including the multicast address does not flow except for the IGMP message.

  When the host HT wants to receive a multicast packet, the host HT transmits an IGMP report (report) message including multicast address information (which may be simply described as a multicast address) to be received to the router RT.

  The layer 2 switch SW that performs normal IGMP snooping stores the multicast address that requests reception in the IGMP report message, and the second port connected to the host HT from the first port (# 1) 21 connected to the router RT. (# 2) 21 is set to transfer a multicast control frame including this multicast address.

  In the layer 2 switch SW according to the embodiment of the present invention, the IGMP report message and the port information (here, port number # 2) of the reception request source (source) are sent from the internal switch 20 to the multicast traffic control unit 10. The multicast traffic control unit 10 holds it. Thereafter, the multicast traffic control unit 10 issues a setting request to the classifier 40 corresponding to the reception request source port 21.

  This setting request includes a multicast address for the classifier 40 to classify the multicast frame and information (queue number) of the queue 30 for storing the classified multicast frame. The classifier 40 receives the multicast traffic from the multicast traffic control unit 10. After receiving the setting request, when a multicast frame including the multicast address arrives, the frame is transferred to the designated queue 30.

  Next, the multicast traffic control unit 10 makes a setting request to the scheduler 50 corresponding to the reception request source port. This setting request includes information on the queue 30 specified in the setting request to the classifier 40 and information on how the scheduler 50 schedules frames in the queue 30 (QoS setting information such as bandwidth and priority). ). After receiving the setting request from the multicast traffic control unit 10, the scheduler 50 is in a state of scheduling the frames in the queue 30 with the instructed QoS.

  The multicast traffic control unit 10 requests the internal switch 20 to transfer the multicast frame including the multicast address to the reception request source port (# 2) 21.

(Release operation when snooping IGMP)
FIG. 5 shows only the configuration of the main part necessary for explanation of the release operation in the layer 2 switch SW according to the embodiment of the present invention whose detailed configuration is shown in FIG.

  In control of multicast traffic between a router and a host by normal IGMP (in the case of IGMPv1, v2, and v3), when the host HT wants to stop receiving multicast packets, the router RT periodically transmits an IGMP query ( Query) message, that is, the IGMP report message (keep alive response) for the keep alive message including the multicast address information of the multicast stream to be stopped is stopped.

In IGMPv2 and v3, the host HT transmits an IGMP leave message including the multicast address information of the multicast stream to be stopped to the router RT before stopping the reply of the IGMP report message. The router RT is connected to the first port (port number # 1) 21 in which transmission of multicast traffic is set.
An IGMP query message is periodically transmitted, and it is confirmed whether or not there is a host HT receiving the traffic of the multicast address at the port.

  In the IGMPv1, v2, and v3, the router RT stops forwarding the multicast traffic to the port when the IGMP report message is not returned. The router RT first receives an IGMP leave message from the host HT in IGMPv2 and v3. When receiving the IGMP leave message, the router RT wants to transmit an IGMP query message to the received port and receive a packet of the multicast address. Check if there is any other host HT. If the IGMP report message is not returned, the router RT determines that there is no other host HT that it wants to receive, and stops forwarding multicast traffic to the port.

  As a result, the layer 2 switch SW that performs IGMP snooping can recognize it as an opportunity to cancel the IGMP snooping setting by monitoring the IGMP query message and the IGMP report message.

  Next, the operation for canceling the multicast frame transfer setting will be described in more detail. Here, the router RT is connected to the interface unit 60 (not shown) corresponding to the first port (# 1) 21 in the internal switch 20 via a network communication line, and the second and third ports (# 2, # 3) Similarly, the host HT is connected to the interface unit 60 (not shown) corresponding to 21. Also, the multicast frame “01: 00: 5e: aa: aa: aa: aa” (hereinafter abbreviated as “aaa”) is transferred to the second and third ports (# 2, # 3) 21. Settings are made. From the router RT, an IGMP query message is periodically transmitted. In response to reception of an IGMP leave message from the host HT, an IGMP query message is transmitted from the router RT.

  In the layer 2 switch SW having the normal IGMP snooping function, the IGMP query message transmitted from the router RT is transmitted from the first port (# 1) 21 of the internal switch 20 to all other ports (here, the second and second ports). 3 is transferred to each host HT via the port (# 2, # 3)) 21, and if no IGMP report message is returned from each host HT, the multicast traffic transfer setting is canceled.

  In the layer 2 switch SW according to the embodiment of the present invention, the IGMP query message transmitted from the router RT is transmitted from the first port (# 1) 21 of the internal switch 20 to all other ports (here, the second and second ports). This is transferred to each host HT via the third port (# 2, # 3)) 21, and this IGMP query message is sent from the internal switch 20 to the multicast traffic control unit 10. After receiving the IGMP query message from the internal switch 20, the multicast traffic control unit 10 starts a timer value counting operation for each port (# 2, # 3) for which the multicast address transfer is set in the timer 13. .

  Thereafter (before the timeout), when the internal switch 20 receives the IGMP report message from the host HT, the internal switch 20 transfers the IGMP report message to the router RT, and also transmits the IGMP report message and the IGMP report message to the multicast traffic control unit 10. The information (port number # 2) of the port 21 that has arrived is transferred.

If the IGMP report message arrives from the internal switch 20 before the timer 13 times out, the multicast traffic control unit 10 stops the count operation of the timer 13 corresponding to the port. When there is a port 21 for which the timer 13 has timed out, the multicast traffic control unit 10 stops forwarding the multicast frame to the timed-out port 21 and further cancels the QoS setting of the timed-out port 21.

  FIG. 5 illustrates a case where the second port (# 2) 21 of the internal switch 20 receives an IGMP report message from the host (# 1) HT and the third port (# 3) 21 times out. Yes. The multicast traffic control unit 10 issues a setting cancellation request to the internal switch 20 so as to cancel the multicast frame transfer setting of the multicast address “aaa” in the port (# 3) 21.

  Next, the multicast traffic control unit 10 requests the classifier 40 corresponding to the port (# 3) 21 to cancel the setting of the multicast address “aaa”. This setting cancellation request includes multicast address information (“aaa”). After receiving the setting cancellation request, the classifier 40 clears the setting related to the multicast address “aaa”, and the queue assigned to this address “aaa” Release 30.

  Further, the multicast traffic control unit 10 issues a setting cancellation request to the scheduler 50 corresponding to the port (# 3) 21. This setting cancellation request includes information (queue number) of the queue 30 used for the multicast address “aaa”. After receiving the setting cancellation request, the scheduler 50 clears the scheduling setting for the queue 30 and sets the multicast address “ The queue 30 allocated to “aaa” is released.

  As a result, the setting related to the multicast address “aaa” for the third port (# 3) 21 is canceled, and the state before the multicast address “aaa” is set is restored.

(Setting operation when snooping PIM-SM)
In the control of multicast traffic between routers and routers by normal PIM-SM, the operation at the time of setting the forwarding of multicast traffic is the same as the above-mentioned “setting operation when snooping IGMP”, and the snooping target message is IGMP report. It just replaces the message with the PIM-SM join message.

(Release operation when snooping PIM-SM)
FIG. 6 shows only the configuration of the main part necessary for explanation of the release operation in the layer 2 switch SW according to the embodiment of the present invention whose detailed configuration is shown in FIG.

  In the control of multicast traffic between routers and routers by normal PIM-SM, the receiving router RT explicitly transmits a PIM-SM leave message to the transmitting router RT when it is desired to stop receiving multicast packets.

  When receiving the PIM-SM leave message transmitted from the receiving router RT, the transmitting router RT stops forwarding multicast traffic to the receiving router RT that transmitted the PIM-SM leave message.

  Therefore, the layer 2 switch SW that snoops the PIM-SM can recognize the trigger for releasing the PIM-SM snooping setting by monitoring the PIM-SM leave message from the receiving router RT.

Next, the release operation when multicast traffic forwarding is set in the layer 2 switch SW by PIM-SM snooping will be described in more detail.

  Here, the transmission router RT is connected to the interface unit 60 (not shown) corresponding to the first port (# 1) 21 in the internal switch 20 via a network communication line, and the second and third ports ( Similarly, receiving routers (# 1, # 2) RT are connected to the interface unit 60 (not shown) corresponding to # 2, # 3) 21. Also, the multicast frame “01: 00: 5e: aa: aa: aa: aa” (hereinafter abbreviated as “aaa”) is transferred to the second and third ports (# 2, # 3) 21. Settings are made.

  In the layer 2 switch SW having a normal PIM-SM snooping function, the first port (# 1) 21 of the internal switch 20 is connected to the PIM from either the second or third port (# 2, # 3) 21. -When the SM leave message arrives, the PIM-SM leave message is transferred to the sending router RT, and the multicast traffic transfer setting for the third port (# 3) 21 where the PIM-SM leave message arrives is cancelled. .

  In the layer 2 switch SW according to the embodiment of the present invention, when the PIM-SM leave message transmitted from the receiving router (# 2) RT reaches the third port (# 3) 21, the internal switch 20 The PIM-SM leave message is transferred to the first port (# 1) 21 to which the transmission router RT is connected, and the PIM-SM leave message and the PIM-SM leave message arrive at the multicast traffic control unit 10 The port information (port number # 3) is transferred.

  The multicast traffic control unit 10 stops forwarding the multicast frame to the third port (# 3) 21 that has received the PIM-SM leave message from the receiving router RT, and further times out the second port (# 2) that has timed out 21 QoS setting is canceled.

In FIG. 6, the first port (# 1) 21 is connected to the PIM-SM from the third port (# 3) 21.
The case where a leave message is received is illustrated. The multicast traffic control unit 10 issues a setting cancellation request to the internal switch 20 so as to cancel the multicast frame transfer setting of the multicast address “aaa” of the port (# 3) 21.

  Next, the multicast traffic control unit 10 requests the classifier 40 corresponding to the port (# 3) 21 to cancel the setting of the multicast address “aaa”. This setting cancellation request includes multicast address information (“aaa”), and after receiving the setting cancellation request, the classifier 40 clears the setting relating to the multicast address “aaa”, and the queue assigned to this address “aaa” Release 30.

  Further, the multicast traffic control unit 10 issues a setting cancellation request to the scheduler 50 corresponding to the port (# 3) 21. This setting release request includes information (queue number) of the queue 30 used for the multicast address “aaa”, and the scheduler 50 clears the scheduling setting for the queue 30 after receiving the setting release request, and this address The queue 30 assigned to “aaa” is released.

  As a result, the setting related to the multicast address “aaa” for the third port (# 3) 21 is canceled, and the state before the multicast address “aaa” is set is restored.

[Modification]
Each process in the above-described embodiment can be similarly performed in the case of other multicast control protocols. For example, the multicast control protocol is selected according to the difference in the application network such as the scattered state of the multicast group members.

  The processing in the above-described embodiment is provided as a computer-executable program, and can be provided via a recording medium such as a CD-ROM or a flexible disk, and further via a communication line.

[Others]
(Appendix 1) A layer 2 switch that forwards a multicast frame in a packet form only to a necessary port connected to a router or a host by snooping a multicast control frame;
A switch unit that performs layer 2 switching between a plurality of ports in accordance with a setting instruction;
Based on the multicast address of the multicast control message content obtained by snooping the multicast control frame flowing through this switch unit, and the port of the switch unit to which the multicast frame to be transferred is to be transferred based on the source port information to which this message has arrived A control unit for instructing the switch unit to set a switch path and determining and instructing to set at least one queue for temporarily storing the multicast frame to be transferred and the QoS of the queue;
A classifier that inputs the multicast frame to be transferred to a predetermined queue in accordance with a setting instruction from the control unit;
A scheduler that sets QoS of the predetermined queue in accordance with a setting instruction from the control unit;
When the control unit recognizes the cancellation of the multicast frame transfer setting based on the snooping information, the control unit requests the switch unit, the classifier, and the scheduler to cancel the setting. Layer 2 switch. (1)
(Appendix 2) Located between routers and routers or between routers and hosts,
The layer 2 switch according to claim 1, wherein a protocol of the multicast control message is PIM-DM, PIM-SM, PIM-SSM, or DVMRP between the routers and routers, and IGMP or MLD between the routers and hosts.

(Additional remark 3) The said control part memorize | stores the information which contains the use queue with respect to the multicast address preset or dynamically set by the operator, and QoS of this use queue in a 1st list | wrist, Information of this 1st list | wrist The multicast address and its allocation queue are instructed to the classifier corresponding to the port to which the multicast frame to be forwarded is to be forwarded, and the scheduler corresponding to the port to be forwarded is queued. The layer 2 switch according to appendix 1, which instructs QoS setting. (2)
(Supplementary Note 4) When the multicast control message and the source port information to which the message has arrived are transferred from the switch unit as snooping information, the control unit sets the multicast address in the multicast control message. The layer 2 switch according to appendix 3, wherein the layer 2 is read and written to the second list together with the source port information. (3)
(Additional remark 5) When the said control part compares the multicast address in the said 2nd list | wrist with the multicast address in the said 1st list | wrist after writing to the said 2nd list | wrist, both multicast addresses correspond Use queue information and Q from the first list.
The layer 2 switch according to appendix 4, wherein the OS setting information is read and a setting request is made to the classifier and the scheduler corresponding to the source port to which the multicast control message has arrived. (4)
(Supplementary Note 6) When the control unit receives the release request from the host, the multicast control message for release and the source port information to which the message has arrived are transferred from the switch unit. Read the multicast address in the message for comparison with the contents of the second list, and if the multicast address exists in the second list, delete the multicast address from the second list;
After deleting the multicast address from the second list, the multicast address is compared with the contents of the first list, and if both multicast addresses match, the multicast control message for release has arrived The layer 2 switch according to appendix 5, wherein a release request is issued to the classifier and the scheduler corresponding to the source port. (5)
(Supplementary Note 7) When the control unit receives the keep alive multicast control message transmitted from the router through the switch unit, the control unit reads the multicast address in the message and reads the contents of the second list. In comparison, if the multicast address is present in the second list, when there is no multicast control message for a keep-alive response from the host within the time specified by the protocol, the multicast address is set to the second list. Remove from the list,
After deleting the multicast address from the second list, the multicast address is compared with the contents of the first list, and if both multicast addresses match, a multicast control message for the keep-alive response The layer 2 switch according to claim 5, wherein a release request is made to the classifier and the scheduler corresponding to a port that does not reach the port.

The block diagram which shows the structure of the IP network system to which the layer 2 switch of one embodiment of this invention is applied. The block diagram which shows the structure of the layer 2 switch of one embodiment of this invention. The figure for demonstrating the detail of the information which the multicast traffic control part of the layer 2 switch shown in FIG. 2 hold | maintains. The figure for demonstrating the setting operation | movement in the case of snooping IGMP. The figure for demonstrating the cancellation | release operation | movement when snooping IGMP. The figure for demonstrating cancellation | release operation | movement when snooping PIM-SM.

Explanation of symbols

SW Layer 2 switch RT Router HT Host 10 Multicast traffic control unit 11 Setting list 12 Snooping result list 13 Timer 20 Internal switch (switch unit)
21 Port 30 Queue 40 Classifier 50 Scheduler 60 Interface unit 70 Dedicated port

Claims (5)

A layer 2 switch that forwards a multicast frame in a packet form only to a necessary port connected to a router or a host by snooping a multicast control frame;
A switch unit that performs layer 2 switching between a plurality of ports in accordance with a setting instruction;
Based on the multicast address of the multicast control message content obtained by snooping the multicast control frame flowing through this switch unit, and the port of the switch unit to which the multicast frame to be transferred is to be transferred based on the source port information to which this message has arrived A control unit for instructing the switch unit to set a switch path and determining and instructing to set at least one queue for temporarily storing the multicast frame to be transferred and the QoS of the queue;
A classifier that inputs the multicast frame to be transferred to a predetermined queue in accordance with a setting instruction from the control unit;
A scheduler that sets QoS of the predetermined queue in accordance with a setting instruction from the control unit;
When the control unit recognizes the cancellation of the multicast frame transfer setting based on the snooping information, the control unit requests the switch unit, the classifier, and the scheduler to cancel the setting. Layer 2 switch. The control unit stores information including a use queue for a multicast address set in advance or dynamically by an operator and QoS of the use queue in the first list, and based on the information of the first list, Instructs the classifier corresponding to the port to which the multicast frame to be transferred is to be set to set a multicast address and its allocation queue, and instructs the scheduler corresponding to the port to be transferred to set the QoS of the queue. The layer 2 switch according to claim 1. The control unit reads the multicast address in the multicast control message when the multicast control message and the source port information to which the message has arrived are transferred from the switch unit as snooping information, and the transmission The layer 2 switch according to claim 2, wherein the layer 2 switch is written in the second list together with the original port information. The control unit compares the multicast address in the second list with the multicast address in the first list after writing to the second list, and if both multicast addresses match, The layer 2 switch according to claim 3, wherein information on use queue and QoS setting information are read from the first list, and a setting request is made to the classifier and scheduler corresponding to the source port to which the multicast control message has arrived. . In response to a release request from the host, the control unit transfers the multicast control message for release from the switch unit and the source port information to which the message has arrived. Read the multicast address and compare it with the contents of the second list, and if the multicast address exists in the second list, delete the multicast address from the second list;
After deleting the multicast address from the second list, the multicast address is compared with the contents of the first list, and if both multicast addresses match, the multicast control message for release has arrived The layer 2 switch according to claim 4, wherein a release request is issued to the classifier and the scheduler corresponding to the source port.

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