JP4500781B2 - Ethernet network topology confirmation method - Google Patents

Description

  The present invention relates to a method for confirming the network topology of a layer 2 (hereinafter referred to as L2) switch in an Ethernet (registered trademark) (Ethernet / IEEE802.3 / hereinafter referred to as EN) network.

  In an environment where a plurality of L2EN switches are used in a carrier service or a corporate network, confirmation of the network state and route is required. The topology of the L2EN network has been confirmed by the following method.

(1) Confirmation by SNMP manager By obtaining MIB (Management Information Base (RFC1156) (RFC1213)) of each device (L2EN switch), various device information such as confirmation of device UP / DOWN and interface information is obtained. Thus, the icons created on the SNMP manager are manually arranged according to the assumed configuration, and the trap is monitored to check the state of the L2 network.

(2) Confirmation based on in-device information The L2EN switch creates an FDB (Forwarding Database) based on source MAC learning. However, in an L2 switch that does not serve as a transmission source but only relays, it is not possible to confirm which L2 switch is connected to the neighbor only by checking the FDB. By accessing each device and confirming which MAC address exists at which port, one by one, the topology is grasped, and by using LLDP (Link Layer Discovery Protocol) together, It is possible to confirm information on neighboring devices.

(3) Confirmation by STP To create a loop prevention topology between L2 switches, such as when a redundant configuration is required in an L2EN network environment, STP (Spanning Tree Protocol (IEEE 802.1d)) or MSTP (Multiple Spanning Tree) Protocol (IEEE 802.1s)) is used. To confirm the overall topology after creating the topology, access to each device, acquire STP information, and manually analyze the state of each port to grasp the overall topology.

IETF RFC 1156 IETF RFC 1213

  As described above, to confirm the topology of the L2EN network, it is necessary to access all target devices, acquire information, and infer from that in order to acquire various types of information. Therefore, it is only fragmentary information acquisition, it is difficult to determine because it is not a confirmation from the result that the packet actually flows through the target network, and if there are many target devices in the network, one unit is accessed Since it is necessary to obtain information, the burden on the administrator was great.

  In addition, with the confirmation method using SNMP manager, the status of each device can be confirmed from polling of the target device, UP / DOWN of each device, and the acquisition of various information such as interface information. Therefore, it is difficult to accurately grasp the actual packet flow because it is estimated from a combination of various information.

  By using tools such as Ping and Traceroute, it is possible to check the route of the layer 3 IP. However, only the devices to which IP addresses are assigned are targeted, and it is necessary to know the destination IP address to confirm the topology. In other words, since the confirmation is made only between the IP devices that are layer 3, the topology of the L2EN switch between the IP devices cannot be confirmed. Also, when request message is terminated and responded to it, it becomes a confirmation method using ICMP and its response message. Therefore, for layer 2 which cannot understand packet and cannot understand ICMP, from the actual packet flow The topology cannot be understood. In addition, the layer is different from the method of using tools such as Ping and Traceroute, and in Ping and Traceroute, packets are sent and sent back to each router at 1: 1, so many packets must be sent. I must. In addition, the IP address of the return source router is stored in the returned packet, but the address of the relayed router is not stored, so the topology cannot be grasped even if it is received.

  Accordingly, an object is to easily and quickly acquire topology information of an L2 network.

  In order to solve the above-described problems, a request / response type topology confirmation technique for actually flowing a packet to an L2EN network is provided. For example, a “MAC trace header” as shown in FIG. Using this header, device A (1) in FIG. 1b, which is a confirmation device, creates a request packet by the process unit (50) in FIG. 4 and sends it to all terminals by multicast / broadcast using the MAC address (FIG. 1). 1b (pk1)). The range to be checked for topology is limited to the range where this packet can reach, and when all the devices A to H in FIG. 1b are L2EN switches, this request reaches all. If there is an IP device in the middle, the range including the device is the confirmation target range. When the EN Type value in FIG. 2a (20) indicates a MAC trace, each receiving terminal takes in the process part in FIG. 4 (50), assembles a response packet to the request, and configures it as a request transmitting terminal in FIG. Send response packet to (1). Figure 1a Device A (1) is the process part (50) shown in Figure 4 and receives the response packet from all the target devices, assembles the contents to grasp the topology (Figure 9), and displays the information on the screen (Figure 10).

  By the above means, the topology confirmation of the L2EN network can be performed without accessing all the target devices, and since the packet is confirmed by flowing through the target network, the reliability of the topology can be increased. Since the topology state is displayed on the screen based on the collected information, there is an effect of reducing the burden on the administrator who confirms the topology state.

  Problems, means, and effects other than those described above will be clarified by examples described later.

  Examples of preferred embodiments of the present invention will be described below. However, the present invention is not limited to this embodiment.

  FIG. 1a shows an L2EN network and devices AH (1-8) show L2EN switches. The devices A to H having the function of the “MAC trace header” (hereinafter referred to as this function) have the device configuration shown in FIG. 4, and the MAC trace is transmitted and received in FIG. (FIGS. 5a and 5b) / relay processing (FIG. 5c) and creation of topology information (FIG. 5d) from the received packet information.

  Fig. 1b shows a schematic diagram of the protocol operation when this function is operating. MAC trace request packet is sent from device A by multicast / broadcast of MAC address and sent to all devices in the format of Fig. 2a according to the packet format rules of Fig. 2b. (FIG. 1b ((pk1))). When the Type value of the EN header of the received packet (Figure 2a (20)) indicates MAC trace, the devices B to H recognize the upper part as the MAC trace header and process the response in Figure 4 (50). Then, as shown in FIG. 1b, a response packet is returned to the transmitting apparatus A (FIG. 1b (pk2) to (pk16)). The sequence of FIG. 1b and detailed packet field contents are described in FIG. Each sequence number ((pk1) to (pk16)) in FIG. 1b matches the sequence number ((pk1) to (pk16)) in FIG.

  FIG. 2a shows the MAC trace header. (20) is a Type value of the EN header, which is a value indicating a higher-level protocol. If the MAC trace is specified here, it is processed by the MAC trace process unit of (50) in FIG. (21) is an Option value. When this value is 1, it indicates a MAC trace request, and the part of (pk1) in FIGS. 1b and 3 corresponds. In the case of 2, the device that has received the Option value 1 is used when a response is transmitted to the device, and corresponds to (pk2) to (pk16) in FIG. 1b and FIG. (22) indicates the ID value, and a unique and random value is used for each MAC trace request. By using this value for subsequent responses until this value is completed, the requesting device knows whether it is a response to its own request. To do. (23) indicates the Topology_Origin value, which indicates the MAC address of the MAC trace requesting device. The responding device sends a response packet to the MAC address in this value. (24) is the Version value, and 1 is always used here. (25) indicates the HOP value, and every time it passes through a device that supports MAC tracing, minus 1 is performed. When a HOP value of 1 is received, the device does not forward any further MAC trace packets. used. This is because if the network is in a loop, no load is applied to the device or the network. (26) indicates the Topology_Number value, which indicates how many Topology_N values in (27) are used. (27) is used by a device that transmits a response packet with a Topology_N value or a device that relays it to embed its own MAC address. The requesting device finally grasps and displays the topology by assembling this information. (28) is a FIN value, which indicates to the requesting device that there is no other device under its control and that it is a terminal device of the L2EN network, and gives reliability to the notification of the topology state. The Topology_N value is also called stage information, and the FIN value is also called end information.

  FIG. 2b summarizes the above and shows details of the packet format of FIG. 2a.

  FIG. 3 shows the sequence during the protocol operation of FIG. 1b, and the contents and operation of the packet field. (pk1) indicates a MAC trace request packet from the request transmission device, and (pk2) to (pk16) indicate responses to the MAC trace request packet. As described in FIG. 1b, (pk1) to (pk16) coincide with the sequence numbers ((pk1) to (pk16)) in FIG. 1b.

  FIG. 4 is a block diagram of the L2EN switch and shows the devices AH (1-8) of FIG. 1a performing the MAC trace operation. The packet received by the network interface is sent to the data transfer unit, and the transfer destination is searched based on the destination address of the packet, and transmitted from the network interface corresponding to the searched transfer destination. If the data transfer unit or the process unit determines that the packet is a MAC trace packet, that is, if the MAC trace is shown in FIG. 2a (20), the packet is sent to the process unit for processing. Internally, the MAC trace processing unit 50 existing in the process unit performs request transmission / reception / response / relay / topology confirmation, which is MAC trace processing. The network interface is also called a transmission / reception unit, and the data transfer unit is also called a transmission / reception control unit. Further, the MAC trace process unit 50 has a function of executing the processing described in FIG. 5, and particularly in the example of FIG. A request / response packet determining unit to be executed, a response packet generating unit for executing the processes from A9 to A11, and a topology generating unit for executing the processes from A12 to A14.

  Next, each process of transmission / reception / relay of MAC trace is shown.

FIG. 5a shows an operation flow when the device A transmits and receives the packet having the sequence numbers (pk1) and (pk2) shown in FIGS. 1b and 3. This process is executed in FIG.
(A1) Upon receiving a MAC trace transmission request instruction, apparatus A sets 1 indicating the MAC trace request to the Option value in FIG. 2a (21).
(A2) A value indicating the selector of this request is randomly determined and set to the ID value of FIG. 2a (22). This is used to determine to which request the response packet is received.
(A3) Set its own MAC address to the Topology_Origin value in FIG. 2a (23). This indicates to which device the responding device should send the response packet.
(A4) Finally, 0 is set except for version (FIG. 2a (24)) and HOP value (FIG. 2 a (25)), and this request packet is transmitted to the network by multicast / broadcast.
(A5) Device A that has sent out the MAC trace request packet enters a state of waiting for a response packet from the response device.
(A6) When a MAC trace packet is sent in (A4), the reception timer for this request is started at the same time as entering the state of (A5), and the count is continued until it is finished. This is because the device that transmits the MAC trace does not know the topology, and therefore it is impossible to determine which response packet is terminated when it is received.
(A7) When device A that has entered the state of (A5) receives a packet, device A checks (20) in FIG. 2a. If this value indicates a MAC trace, device A transmits the packet to FIG. 4 (50). hand over. If FIG. 2a (20) does not show a MAC trace, it is a normal L2EN switch process.
(A8) In FIG. 4 (50), the Option value of this packet is checked to determine whether it is a response packet or a request packet. In case of 2, go to (A10). In case of 1, go to (A9).
(A9) Since it is a MAC trace request packet, the processing of FIG. 5b is performed.
(A10) Figure 2a (22) is the same value as the ID value set in (A2) or Figure 2a (23) is the same value as the own MAC address set in (A3). If both are the same, (A4) It is determined as a response packet to the request packet sent in step (1). If not (A11), the process of FIG. 5b is performed. It is necessary to confirm both, because the ID is a random value, so that it is possible to prevent duplication with other requests.
(A12) If it is determined as a response packet to the packet sent by itself, the MAC address of the device through which the response packet has passed is embedded in Topology_N by the Topology_Number value in FIG. 2a (26). Then, the topology information is held for each Topology_N and for each received response packet as shown in (1) of FIG. 5d.
(A13) Wait for the timer (A6) to expire. If an end notification has not yet been received, a preparation is made for adding a value when the next response packet is received in (A12). When the end notification is received, go to (A14).
(A14) Based on the information of FIG. 5d (1) held in (A12), the process of FIG. 5d (2) is performed. Here, the information held in FIG. 5d (1) is rearranged by Root_N in the descending order of N values of Topology_N as shown in FIG. 5d (2). Therefore, a topology is created by connecting overlapping MAC addresses for each Root_N.
(A15) When the topology creation is completed, the topology state is displayed on the screen as shown in FIG. If there is no FIN setting, this is displayed and the possibility that another device exists after that is displayed.

FIG. 5b shows an operation flow when the device B receives the MAC trace request packet and transmits the response packet in (pk1) of FIG. 1b and FIG.
(B1) When device B receives the packet, if the value in FIG. 2a (20) indicates a MAC trace, device B sends the packet to FIG. 4 (50) and proceeds with the process. If not, the packet is processed by the normal L2EN switch operation.
(B2) When the processing of (B1) is performed and the request packet is multicast / broadcast, it is flooded to another port according to the setting of device B.
(B3) After the processing of (B1), the Option value of the received packet is examined in the process part FIG. 4 (50).
(B4) If the Option value is determined to be 2 in (B3), it is determined that the packet is a MAC trace response packet, and the relay process goes to FIG. 5c.
(B5) Since the Option value is 1, a response packet for the request is assembled. First, the Option value in FIG. 2a (21) is set to 1 indicating the MAC trace response packet, and FIG. 2a (22) (23) of the received MAC trace packet is copied to FIG. 2a (22) (23). Next, after confirming that FIG. 2a (26) is 0, its own MAC address is set in FIG. 2a (27), and 1 indicating that Topology_1 is used is set in FIG. 2a (26). . Finally, if there is a FIN setting according to the specified value, 1 bit is set in FIG. 2 a (28) to indicate that there is no L2EN switch behind the device B. This has the role of giving reliability to the verifier by indicating to the request sending device that there is no device behind him. Since the device C is behind the device C, the FIN setting is not performed, and the value 0 remains in FIG. 5b.
(B6) When the assembly of the response packet is completed, the device B transmits the packet toward the destination set in Topology_Origin of FIG. 2a (23). Although it may be determined whether the response packet is used on the device side received by multicast / broadcast distribution, since each device processes when receiving the response packet, as described later, the load on the device and the network is increased. Unicast is preferred.

FIG. 5c shows an operation flow at the time of relaying the MAC trace packet by the device B at the time of (pk3) (pk4) in FIG. 1b and FIG.
(C1) When a packet is received, it is checked whether or not FIG. 2a (20) is a MAC trace request packet.
(C2) As a result of (C1), if it is a MAC trace request packet, it is sent to FIG. 4 (50), the Option value in FIG. 2a (21) is examined, and if it is 2, it is determined as a MAC trace response packet.
(C3) If FIG. 2a (22) (23) is the value sent by itself, the process proceeds to the response packet reception process of FIG. 5a.
If it is different, this is regarded as a MAC trace relay packet.
(C4) Assemble the relay packet. First, the values of the received packets shown in FIGS. 2a (21) (22) (23) (28) are copied. Next, since Topology_N in FIG. 2a (27) is set only for the value indicated by Topology_Number in FIG. 2a (26), the whole is copied. According to FIG. 3, since one Topology_N is set in (pk2), 6 bytes are extracted and Topology_1 is copied. Thereafter, the own MAC address is set in Topology_N in FIG. 2a (27). In FIG. 3 (pk4), Topology_Number is set to 2 and its own MAC address is set to Topology_2, compared to (pk3). The HOP value of the last received MAC trace packet is decremented by 1.
(C5) Since the assembly of the response relay packet is completed, the packet is transmitted to the destination set in Topology_Origin in FIG.

  By performing the operation as described above, the device A (1) in FIG. 1b finally receives the response packets from the devices B to H (2 to 8), and the contents of the topology are grasped according to FIG. 5d. By performing the processing for this, the topology state is finally displayed on the screen as shown in FIG.

  FIG. 5d shows the process performed in FIG. 5a (A14). After the request transmitting apparatus sends out the MAC trace request packet, the response packet is received from each L2EN switch, and the contents of each packet in FIG. 2a (27) are shown. Shows how to assemble Topology_N and determine topology. First, apparatus A holds Topology_N of the received MAC trace response packet for each Topology_N (1). Next, for each received packet, the contents are rearranged in descending order of Topology_N and held in the form of Root_N (2). Based on this, the topology state is calculated. Since B and D exist in Root_1, it can be seen that there are paths from the requesting device A to the two devices. First, looking at the B side, comparing packet numbers (pk2) and (pk4) reveals that Root_2 does not exist in (pk2), so (pk2) is incorporated into (pk4) and one route is determined. . Since C is FIN-set, it can be seen that there is no L2 switch behind C, so that the L2 network is terminated here. Next, looking at the D side, (pk5) is incorporated because (pk5) does not have Root_2 and E exists otherwise. Then, looking at Root_3, since F, G, and H exist except (pk7), (pk7) is also incorporated, and after E, there are three units of F, G, and H. By determining one route, it is possible to grasp the topology starting from the MAC trace requesting device as shown in (3). In addition, although the process which rearranges in order with the largest Topology_N is performed, the process may be the process of searching in the order of the largest Topology_N without rearranging. Alternatively, device information (routed switch information) such as a MAC address stored in the response packet may be extracted and arranged in order from the end of the packet data without explicitly using Topology_N.

  FIG. 6 shows an example of output displayed on the screen as a result of the process of FIG. 5d in the process performed in FIG. 5a (A15).

L2EN network configuration example Overview of protocol operation Packet format example Packet format field specification example Packet sequence example Example of L2 switch configuration Device A MAC trace process send / receive flow example Device B MAC trace process response flow example Device B MAC trace process relay operation flow example Example of topology assembly algorithm for device A Device A topology output image example

Explanation of symbols

1-8 L2EN switch 20 EN header Type value 21-28 MAC trace header 50 MAC trace process part

Claims (9)

A switch connected to a layer 2 network formed by a plurality of switches,
A transmitter for transmitting the first type packet to the plurality of switches;
A receiving unit that receives a second type packet that is a reply to the first packet from each of the plurality of switches;
A switch comprising: a topology creation unit that creates topology of the plurality of switches based on stage information included in the second packet and transit switch information stored corresponding to the stage information. The switch of claim 1, wherein
The topology creation unit arranges the transit switch information included in the second type packet in order according to the stage information for each of the plurality of second type packets, and compares the transit switch information in the same stage order. Switch. The switch of claim 2, wherein
The topology creation unit compares the second transit switch information in the next stage order for a plurality of second type packets having the first transit switch information that matches in the same stage order. It is determined that the first transit switch information corresponds to a branch point. The switch of claim 2, wherein
The topology creation unit compares the second transit switch information in the next stage order for a plurality of second type packets having the first transit switch information that matches in the same stage order. A switch that creates a topology in which a switch corresponding to each second transit switch information is connected to the first transit switch information. The switch of claim 1, wherein
The type 2 packet includes end information indicating the end of the layer 2 network,
The topology creating unit creates a topology having a terminal of the transit switch information corresponding to the terminal information as a terminal. A switch connected to a layer 2 network formed by a plurality of switches,
A transmitting / receiving unit for transmitting and receiving packets;
A request / response packet determination unit for determining whether a packet received by the transmission / reception unit is a request packet or a response packet;
When the request / response packet determination unit determines that the request packet is a response packet, the response packet generation unit generates a response packet including the address and stage information of the switch based on the identification number of the request packet;
A switch comprising: a transmission / reception control unit that causes the transmission / reception unit to transmit a response packet created by the response packet creation unit and a request packet received by the transmission / reception unit. The switch of claim 6, wherein
The response packet creation unit adds terminal information to the response packet when there is no switch connected to the switch other than the packet that transmitted the request packet. A switch connected to a layer 2 network formed by a plurality of switches,
A transmitting / receiving unit for transmitting and receiving packets;
A request / response packet determination unit for determining whether a packet received by the transmission / reception unit is a request packet or a response packet;
If the request / response packet determining unit determines that the packet is a response packet, a response packet including the stage information and the address information of the switch is created to follow the set of the stage information and address information included in the response packet. A creation department to
And a transmission / reception control unit that causes the transmission / reception unit to transmit the response packet created by the response packet creation unit. A topology confirmation method executed in a layer 2 network formed by a plurality of switches,
The first switch sends a request packet,
The second switch that has received the request packet transfers the request packet to the third switch and the fourth switch, and includes a MAC address of the second packet and responds to the request packet. Create a packet and send it to the first switch;
The third switch creates a second response packet that includes the MAC address of the third switch and responds to the received request packet, and transmits the second response packet to the second switch.
The fourth switch generates a third response packet that includes the MAC address of the fourth switch and responds to the received request packet, and transmits the third response packet to the second switch.
The second switch adds the MAC address of the second switch to each of the received second response packet and the third response packet, and transmits to the first switch,
The first switch extracts a MAC address included in the received first to third response packets, and determines that the second switch corresponding to the commonly included MAC address is a branch point. Topology confirmation method characterized by

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