TWI229993B - Topology loop detection mechanism - Google Patents

Abstract

Broadcast storm due to topology loop may result from end-user mis-configurations, faulty ports, cabling problems, faulty spanning-tree algorithm implementations, and others. This loop detection mechanism helps detecting topology loops and eliminates them. It operates as a watchdog independent of the spanning-tree algorithm. The feature is aiming at enhancing the values of SOLOS.

Description

1229993 V. Description of the invention (1) What the invention belongs to The present invention relates to a mechanism in the topology loop. The hair ^ is a topology loop, which has nothing to do with other equipment in the network. f is related to the detection topology. The prior art broadcast storm (broadcast st om) b 丄 road (LAN, local area netwQr) ^ 1 the loop of the helmet of the connected multicast packet. The relationship between the broadcast packet and the multicast circle of the state, and the relationship between the poor and the equal = due to the network topology ^ ^ Cforward) a, ^ ^ fl] relationship, the network topology loop is a feedforward redundant path: The good thing about Cunsheng is that it consumes network bandwidth inefficiently and can't be placed to handle repeated traffic. Therefore, " If a frame is sent to the parent of the 5th generation of the 5th transformation, the cross frame is fed back to ⑽ to analyze the loop frame-which is completed by using the ^ & project, which The table can direct the frame of the target dlT AC address (such as the switch MAC with I / G settings) to the existing loop detection method. One of them is to use the spanning-tree protocol (STp). Loop network topology. Under normal circumstances, STP remains enabled on the network. However, network topology loops can still lead to some of the following situations: 1 STP implementation may have disadvantages and sometimes cannot be obtained without Page 5 of 11872twf.ptd 1229993

Topology. 2. Port hardware may have disadvantages that prevent it from responding properly to STp operations. 3. STP may be deliberately or unintentionally disabled on a regional or remote switch or certain ports. The end user may then erroneously operate the switches without seeing that the topology is loopless. 4. The port hardware may have disadvantages that prevent it from transmitting or receiving packets, resulting in unidirectional traffic. In addition, partially broken cables can cause unidirectional traffic. Under the current circumstances, STP will thoughtlessly convert a closed port (biocking port) into a feed because the port (or its equivalent) does not receive the Bridge Protocol Data Uni t, BPDU). The IEEE 802. 3ad connection aggregation (iink aggregation) connection method may be wrong, and the frame sent from the connection aggregation is returned to the connection aggregation. ', 6. There may be a wrong connection set. There are different ports on both sides of the connection.口 7. Virtual Local Area Network (V & LAN) translation may be enabled intentionally or unintentionally on the remote switch. End users may then not realize that the topology is loopless And these switches are operated by mistake. ^ 8. The bridge between the La ^ er 3 (L3) interfaces is enabled, but the resulting topology is not free from loops. 鳘 Content Therefore, the present invention provides a loop Detection mechanism method, one of which is special

1229993 、 Explanation of the invention (3) $ = ^ π feed forward and observe whether the box will be received on a feed forward converter: jjm: box will be received by the front feed port on the remote switch or area switch . Huh! : Park loop, the frame will be processed by the area cpu for further analysis, but it will not be able to capture the frame to the circle detection i 一 = a goal is to operate the back to the link even if the STP mechanism does not work properly-the other is- The goal is to detect loops in situations where STP is not working properly (such as a single Ao green). · The local system consumes the network bandwidth, otherwise, is the machine ί :: ί :: The goal is to carefully assume that the remote (or equivalent) switch is _ming and circle-detected network os, and assume its Capabilities and settings. Another goal of Ming is to operate under the wired collection layer. Prevent topology loops. According to the above it circle detection mechanism to provide a non-broadcasting wind, as described above, the mechanism of the present invention has the following characteristics: 1. It operates outside the STP mechanism architecture. Loop 2. · Effects can be detected even when STP does not work properly (such as one-way connection) 3. · Consume less network bandwidth, otherwise it will cause a bad network to the network ^ Do not set whether the remote (or equivalent) switch performs loop pick-up and test, and does not assume its ability and set up. 11872twf.ptd Page 7

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5 · It operates under the wire collection layer. The present invention includes the objective of the loop detection mechanism in the phase described below. In order to achieve the above objectives and implementation, and provide Gamma ..., the above and other objectives, features and advantages of the present invention can be clearly understood from the detailed description of the embodiment, and the embodiments can be understood with reference to the drawings. It is to be understood that the above description and the following detailed description are merely examples for further explanation of the present invention.

First, the present invention provides a basic concept of a loop detection mechanism, which sends a special multicast frame on a forward port and observes whether the frame will be received on a forward port. If there is no topology loop, the box will be dropped on some closed ports of the remote switch or area switch. If there is a loop, the frame will be received on the feedforward port of the area switch. The area switch is planned to capture the frame and send it to the CPU for further analysis without the need to feed forward the frame. In order to teach a preferred embodiment of the present invention, the definition of the loop detection mechanism of the present invention will be described in the following stages: • Frame type, transmission, reception and feedback, analysis, operation, and detection scheme. Other considerations and command line interfaces will be described later. > Frame type The frame format of this loop detection frame is listed in the table in Figure 1. The destination media access control (DMAC)

11872twf.ptd Page 8 1229993 V. Description of the invention " " The address is, for example, 01-80-C2-〇〇-〇〇-2f or the area switch MAC address with the 1 / G bit setting. On the other hand, MAC address 80-c2 1002f is one of the GARP reserved MAC addresses. At present, this address has not been used in any of the following: standard agreement :, so this invention can be used. First & make this frame an evening broadcast frame ’so that there is no distance to the loop detection of the present invention broadcast this frame (face gauge w2.5.G2.1D annual version (face s ^ nfafdf

Sec · 12 · 5 02.1D 1 998 Edition)); and when a topology loop exists, the box can reach the area switch. Second, the region can give higher priority to the frame with this MAC address (same as 卯 ⑽), increasing the possibility that the frame will be received and processed by the CPU under the topology loop and broadcast storm. Using this MAC address will cause the CPU to burden the frame processing, because the frame with this mac address will pass through the closed port, like BPDU. Therefore, it is better to use this only when the switch with ^ number (preferably 1) is used for loop detection; the ^ bit, the better-set partition bridge allows the bit to be sent so that there is no need for the frame 01- The 80-c2 BPDU is processed in real-time. The other option of the target MAC address is a MAC address with the parent state of the I / G bit field. The MAC address used as part of the STp (ii) can be used here. Then, this unique target MAC address can be specifically retrieved by the parent switch of the frame. Opening the I / G border is a multicast box, for the reasons described above. This MAC address is used for priority processing, and the frame is more likely (than the case of -0 0-0 0-2f, the frame is processed into a PDU with a similar rationale or priority) and discarded in the broadcast storm . In addition, software assistance is not required in the box unless its target is the MAC address of a regional switch. This feature makes the cpu burden more

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Low, even with a large number of switches with loop detection turned on. In a preferred embodiment of the present invention, the MAC address of the area switch with the 1 / G bit setting can be used as the target MAC address. The source of the field frame is 00Urce. The MAC address can be the MAC address of the regional switch (the 1 / G bit has been cleared). The MAC address used as part of the bridge α in the STp can be used here, or it can be an address related to some L3 interfaces (VLAN interfaces). It should be noted that the remote switch will learn this "^ address in the feedforward table. In addition, the source MAC address of the box can be the MAC address of the transmission port. If it is helpful to identify the port of the source box. Here ' δί (* interest stall includes several Type-Length-Value (TLV) blocks. Type% 彳 block represents the length (in bytes) of the value to be accessed. Value sub-block It is not necessary, if it exists, it has the value of the TLV field. The DMAC selection is critical because it must be a multicast address (I / G setting) and enable the sender of the frame to easily retrieve it Box. In this preferred embodiment, the switch IsMAC with I / G settings is selected because the switch MAC can uniquely identify the sender of the box. Fetching mechanism = program the L2 feedforward table with an entry This project will direct the box targeting the MAC address to the CPU. Refer to Figures 10 ~ 15, TLVS and its sub-fields will be described here. ^ Test Figure 10 describing the terminator (terminat〇r) According to the present invention, the ‘good practice’ embodiment is that the TLV is necessary. It is used to represent the end of a message and extend the pivot to a special size and bit. The group is aligned. Figure 11 describes the port identifier (identifier). According to the car driver ’s consistent implementation of this month, the TLV is unnecessary. You must know the port from which the frame is issued.

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The information can only come from the source MAC address of the received frame. Sometimes, the loopback mechanism may not be able to obtain the Ethernet frame header. When deciding whether a regional switch is part of a topology loop or if the loop exists at the far end, it is important to know the port where the box originated. Referring to Figure 12 describing the VLAN discriminator, this TLV is necessary according to the preferred embodiment of the present invention. It is used when the source vlan cannot be identified, because the loop detection software module cannot know the VLM tag (tag) or the information obtained by it. Even if the VLAN information is available, it may not be reliable because there may be VLAN translations on the remote switch. Referring to Figure 3, which describes the switch discriminator, according to a preferred embodiment of the present invention, the TLV is unnecessary. It is used when the sender of the frame cannot be identified from the target MA (: address or source MAC address. This may be the case where the loop detection software module cannot know the Ethernet frame header or the information it obtains. Reference Figure 14 describing the time type. According to the preferred embodiment of the present invention, the time type TLV is unnecessary. It helps to identify how long the frame has lasted. It contains information about the clock of the regional switch. " Epoch time "in microseconds. The loop detection mechanism can ignore frames that last for too long, which may be caused by endless loops. It can avoid evils and deliver weight effectively But outdated frames cause replay attacks with false detection. It is recommended to ignore frames that exceed the maximum frame life cycle. The maximum frame life cycle is equal to the maximum bridge transient delay (4 seconds) times the maximum bridge diameter (7 bridges). Add the maximum media access delay for the initial transmission (refer to B · 3 · 1 · 2 of 802.1D). For example, the recommended value is 7 · 5 seconds and cannot exceed 30 seconds. Figure 15 according to the invention

H872twf .ptd Page 11 1229993 V. Description of the Invention (8) ----- Known examples of the car father, this sum check τ L V is necessary. It helps verify the frame ’and avoid maliciously disguising the loop detection frame to interfere with the network. The sum check algorithm and the algorithm's golden key may differ from switch to switch. For example, the 16-bit MD5 sum check is calculated from the loop detection software and the random golden key generated by the overall Ethernet $ verse that excludes the CRC with the excluding the sum check TLV value field. The random golden key can be changed over time to avoid sending out a replay attack in the same frame that would cause loop detection. If the box received fails verification by the sum check, the box is considered invalid. Transmission The transmission introduced by the present invention will be described here. The loop detection frame is sent out the previous feed port on the specified VLAN. However, it can also be sent to a non-feedforward port. Topology loop tests are performed on each VLAN. Although the STP calculation topology of the VUN of the same STP must be the same, it is better to test the topology loop of each operating VLAN. One reason is that allowed VLANs may vary from port to port. Another reason is that the STP status in the hardware may be per-port-per-VLAN. 〇It is usually expected that the loop detection frame sent by a port belonging to one of the VLANs to be tested is sufficient to detect extensions on the VLAN. Park Loop. However, some topological loops are caused by one-way j-line, and it is impossible to detect if the loop detection frame is always sent on a port = this situation. For example, in Fig. 4, switch A and switch B are connected by two wires. Switch A is assumed to be the STP root bridge, but due to the single-line relationship, its BPDU cannot reach the switch “i” of switch b. This will cause all connections to be in a feedforward state. Assume that only switch B performs loop detection. .If the loop detection box is sent only at port2, it will not reach the traffic again.

Page 12 1229993 V. Description of the invention (9) Converter A. Therefore, on a switch that performs loop detection, a loop detection frame must be sent on all feedforward ports. On the other hand, it is better to limit the network and CPU load by limiting the number of frames sent. The characteristics of low-speed protocol transmission in Appendix 43B (Annex 43B of IEEE802.3ad, 2000) describing KIEEE802.3ad, 2000 = Yes, the maximum traffic load per port is limited to 50 frames / second. Taking this as a reference, the algorithm of the first transmission can be as follows: The pass 1 can be seconds, and all the frames of the regional switch are regarded as the loop detection frame ii • For each port, send a loop detection frame at T ^, jVLANj, ^^^ 5〇 ^ t # VLAN, an- are the same. For example, use a last-VID-used variable on each port. From the "VID" box on the VLAN. Then send b for the private port q port ^ Update the variable after transmission. When the variable is 4096, set it back to i. The difference between strong law and strong § weekly quick test, Cang Gong V, the balance between all fair and fair processing: load = two pairs of all good implementation types, because some ASIC switches lead to 2 ::: election is not the most described as follows: Yes Che® There is a description of the second pass algorithm. • Dong Shimian—Second's area grabbing potential ΛΑ ^ J potential detection mechanism:, ^, 5% VLAN as loop detection U • For each VLAN, send A single account occupies all the addresses in the park. A maximum of $, and the frame can be extended to 50 VLANs. Use the overall

11872twf.ptd Page 13 1229993

It works in all VLAN last-VID-used variables in the operation of the agency. It is said that ΛΤΙ inverse This algorithm may lead to a loop detection frame in some period. The worst case is about 80 (4096 / 5Q) l /. Can assume the role: in the operation of a small number of switches (usually less than 50), only receive and change the topology, and will open the (feedforward port) box, the converter on Park The essential device connects one of the ports that can not feed forward to the open loop and feeds it forward to the start loop. The switch receives the other ports of the switch and feeds the frame to the closed port. The detection switch or the exchange of the present invention, when receiving the frame, it must keep this: 5 All other 上 on the topology.

The tested conventional switch is on the enabling topology: if it is not the switch that issued the change, the box is fed forward to the enabling. If the switch sends the box to the CPU to analyze the loop, then when it receives the loop detection box / "Kuang. When the intersecting J box, it must give up the box

When the designated VID of the frame on the switch on one of the enabling topologies is different from the original VID, the six-circle detection frame, but the changed frame is fed forward to the specified enabling, The receiver must receive the loop detection frame without modification and cannot prove all other cockroaches of the top loop. The feed-forward box on VID can further explore the possibility and existence of the topology loop. It is not necessary to specify but can be used if there is no feedforward rule. The feedforward rule is loop 'which will be described in the detection phase. ‘,,, ancient

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Analysis One of the enabling topologies in turn-on loop detection. ^ The parent switch must send out the switch itself. There may have been a frame for bit detection for loop detection analysis. In this case (reduced errors), back to the second, there is a topological circle. For the sake of stability, if the port and stub of this box are issued: The body module must check the port status again. Such as the Park Loop exists. If the ports of the 1 μ frame are in the feed-forward state, there are two topological switches that are different in topology, but the two ports in the region are the same port, so the secret part (as shown in Figure 4) . If the two ports actually exist at the far end (see Figure 5). The Park loop M is at d! V, and there is a switch c between switch A and switch 8 to open the loop; Λ and: there is only one connection between the switches. Suppose that η grabs L 1 for detection. The loop detection frame sent by the switch C will be received on the first port. # OPERATION Once the topology loop is detected, the end user must be notified to remedy the month ^. If possible, the switch should automatically terminate the loop. When the detection switch is part of the topology loop, it can suspend the port, s, and s to prevent it from moving outside the STp control and set the port status to 1 closed. There are two options for the port to be closed: the frame sending port and the frame receiving soil β. The former must be closed because, in the case of a one-way connection, it may be the source of the problem. For example, in Figure 4, the switch B is preferably closed port i instead of closed port2. The closed port can be automatically restored after a period of time j (that is, 3 minutes) caused by the loop detection, so that the end user does not need to access the switch to perform the operation.

11872twf.ptd Page 15 1229993 V. Description of the invention (12)

When the switch detects a remote loop, the switch is not looped. The switch must alert the end user to remedy. ς = The loop detection frame may be repeated many times by the loop. Switch, and + test these boxes to avoid burdening the CPU. This kind of closure can be closed for 3 minutes after a period of time), and then removed, so that if the loop continues to exist for ^ time (that is, the end user is notified. U, ideally, the remote loop can be immediately and automatically Termination. However, the %% of the parent switch cannot be identified in the loop detection box. To note, the ring detection mechanism is designed to have no cooperation with the remote switch. Keli; at 2:

There are many reasons for the formation of topology loops caused by other mechanisms outside the scope of the loop detection mechanism to terminate remote detection. Some of the situations that can be detected by the loop detection mechanism will be described here. It is important to note that there are more than just five scenarios described below. 1) · STP related issues When the switch opens a port that should be closed as a feedforward port, it forms 4: setting circle. This may be caused by faulty STP and i hardware that does not respond properly to STP control. This may be because the port is set to feed back when it should not be feed forward (that is, STP on the port is disabled or the port replication feature is turned on).

2) · One-way connection or one-way connection may be caused by hardware blockage of the port in the transmitting or receiving state. It may also be caused by partially broken cables. Referring to Fig. 4, when there is a unidirectional link $, one end of the link will not receive any BPDUs, so it will be fed back if it crosses. If this end is closed but BPDU is received, it will form a reply

1229993 V. Description of the invention (13) circle. 3). Problems related to the connection set When the connection ends have different connection set structures, a topology loop may be formed. Referring to the example in FIG. 7, switch A and switch B are connected through two connections, and all ports are in a feed-forward state in one case. Then the connections on the parent switch B are aggregated and regarded as two logical ports. The connection on switch a is considered as a separate port. When a broadcast frame is sent from switch B, switch A will feed the frame to switch B through another connection. 4) · VLAN translation Inadvertent use of VLAN translation may cause topology loops. Referring to the example in Figure 8, parent switch A and switch b are connected through four connections, and at this time all ports are in the feedforward state, but the VLAN assignment on the port may be inconsistent, causing the broadcast to be busy between parent A and parent A loop is formed between the switches b. In this example, you can observe that Switch B received Regeneration ™ 2 from VLAN 1 twice, and the second time occurred in Jane. Because: Detecting two requires two =, parent switch B must feed forward when receiving the loop detection frame on VLAN 2 for the first time. Receive the same loop detection for the second time on the switch BkVLAN1 =, the source VLAN in the 'loop loop' box is the same as the specified vlan. 5). Bridge between L3 interfaces Router that allows bridging between L3 interfaces. This kind of bridging comes; ϊ / Same as changing the designated vlan of the bridging frame. Topological loops may also form. ^ Yu Routing and Router B allow the interface between VLAN1 and VLAN2 ^ ‘field and broadcast frame are in parent switch C’ Router A and Router B

11872twf.ptd Page 17 1229993 Five invention descriptions (14) Loop. In this example, cage head @ 出 之 回 园 e, a, observed that switch C received twice from VLAN1, ‘the first time was in VLAN2, and the second time was leaking 1. Because the round trip price measurement frame must receive the same on Guan 2 for the first time — loop detection = i, the second time VLAN is connected on switch C on Ji · 1. The origin of the circle detection box is the same as other considerations. There is a topology loop in Γ. The schedulers are :: m: circle, so, enable the loop on a switch in order to terminate all; measure; cross; circle. Circle detection. , Circle and open back on all parent converters: The $ area parent converter cannot terminate the remote loop, if only in one: test. = A parent switch that needs to select a good switch position to perform a loop can be, for example, a potential topology loop: parent switch. Such exchangers are usually located in a distribution layer. Under normal circumstances, the upload port of the access layer switch is connected to the distribution layer switch. If enabling all ports is important, detecting ^ = circles at the upload port helps more than detecting loops at the edge ports. 3. Thin CPU load When loop detection is supported, it is usually expected to perform loop detection on all switches. At this time, if 01-80-C2 -00-0 0-2 f is used as the target MAC address of the y-ring frame, the CPU will be overloaded. It is better to use a switch with MAC address of 11872twf.ptd, page 18, 1229993 V. Description of the invention (15) I / G bit setting In the ASIC switch engine, give the target: the target MAC address. However, the generation of the deposit detection frame has a high 'priority' and the loop of the MAC address of the switch will be repeated many times. Therefore, the reception = Shipu loop exists, these frames may circle the detection frame and detection Topology loop will not be far from small. Detecting ability All loops cover will be discarded regardless of the price measurement frame. If it is within 1 ~ 80 seconds, although it is limited to the range of the hair and the range, it is considered to be used. 80-c2-〇〇n2f μ & υυ The detectability of the target MAC address cannot guarantee the detection of the known situation. Piao Huihuan, although it has already been described how the mechanism currently seems to be complete, the source may not be reached. Exchange J 'loops for various reasons. For example, Wu may be broadcasted and use the second loop detection frame to transmit the loop detection done within the loop. It will be clear that the example of Ren m ^ is disclosed as above, but the bean is not used to 'when something can be changed; ί: Append without appending to the spirit of the present invention ^ | n ~ +, so the protection of the present invention-patent mallet The area defined shall prevail.

1229993 Schematic description Figure 1 shows the table. Figure 2 shows the instruction list. Figure 3_ Setting table. Figure 4 shows according to the present invention. ^ According to the present invention-the circle detection sash of the preferred embodiment. The circle detection of the preferred embodiment sets the display circle detection of the car driver embodiment. According to the present invention — The fifth embodiment of the one-way connection of a preferred embodiment of Cheng Zhituo, a returnee, shows a block diagram according to the present invention. The block diagram of the circle $ is shown in Figure 6 of the & & block diagram. The STP related topology of the remote topology loop embodiment according to a preferred embodiment of the present invention is shown in Fig. 7. The figure shows the lack of topology caused by the setting of the present invention -1. Figure 8 shows that the set is wrong. According to the present invention, FIG. 9 made by the VLAN translation of a preferred embodiment of the topology of the topology is shown from A to A. σ Topology i is not solidified according to the A connector of the present invention—the bridge between the L3 interfaces of the preferred embodiment continued 1 Λ Topology loop diagram Figure 10_ M i Block diagram according to the present invention ^ The device type table (f11 shows the termination type of the preferred embodiment according to the present invention (TLV). The length value of the preferred embodiment of the TLV stopping type discriminator type table. Figure 12 shows a VLAN according to the present invention. Discriminator type table. 1 ~ TLV of the preferred embodiment

11872twf.ptd Page 20 Brief description of the drawings The intersection of TLV fields of a preferred embodiment Figure 13 shows a table of types of converter discriminators according to the present invention. Fig. 14 shows a table of types according to the present invention. Fig. 15 shows a table according to the present invention and inspection types.

Schematic description Swi tch A: Switch A Swi tch B: Switch B Swi tch C: Switch C Router A: Router A Router B: Router B Total of TLV fields

Claims (1)

1229993 ........ _ 6. Scope of Patent Application 1 · A network topology detection mechanism, including: sending a loop detection frame; and detecting a topology loop. 2 · The loop detection mechanism as described in item 1 of the scope of the patent application, wherein the loop detection frame includes a plurality of stops. The stops include at least: a target media access control (DMAC) address ; And a source media access control (SMAC) address. 3. The topology loop detection mechanism as described in item 2 of the scope of the patent application, wherein the DMAC address is 〇80-c2-00001. 4. The topology loop detection mechanism described in item 2 of the scope of patent application, wherein the DMAC address is a media access control (MAC) address of an area switch with i / g bit setting. 5. The topology loop detection mechanism described in item 2 of the scope of the patent application, wherein the SMAC address is the MAC address of a regional switch with 丨 / G bit clearing. 6 · The topology loop detection mechanism described in item 2 of the scope of the patent application, wherein the $ HAI loop detection frame further includes a type of empty / length 'which contains the length of the loop detection frame. Λ 7: The topology loop detection mechanism described in item 2 of the scope of patent application, wherein the loop detection frame further includes a snap. 8. The topology loop detection mechanism described in item 2 of the scope of the patent application, wherein the loop detection frame further includes a message, which includes a plurality of type-degree-value (T L V) fields. 9. The topology loop detection mechanism described in item 8 of the scope of patent application, 1229993 The loop detection frame further includes a TLV stop. The TLV stop includes: Extending to: = Device 2 shows the end of a message and extending the loop debt measurement frame by 1 A to the size and position of the loop. Group alignment; a port discriminator, determines whether the area switch is part of the topology loop, or the topology loop is located at the far end; a VLAN discriminator, needle sender, because of the bv — Or its information; the loop detection software modules of the loop frames that cannot be discerned cannot obtain the frame [a switch discriminator, which cannot be distinguished from the DMAC address or the ^ ... address The issuer of the loop detection frames; a time stamp to identify how long the loop detection frames have lasted to prevent a replay attack; and a sum check to identify the loop detection frames to prevent A disguised loop detection frame is interfering with the network. 1 0. The topology loop detection mechanism described in item 丨 of the patent application scope, wherein the steps of detecting the topology loop include: a transmission step; a receiving and feedforward step; an analysis step; and Action steps. 1 1 · As described in claim 10 of the patent scope of the similar loop detection mechanism, where the transmission step includes: a first transmission algorithm, emphasis on rapid detection, not overload, and fair treatment of all VLANs Or a balance between multiple ports, including: 1229993 VI. It is possible to transmit the loop detection frame for all ports of the area switch in every second in the patent application range; and send the loop detection frame to the VLAN to be tested on the mother and the VLAN. Feed-forward status, fair treatment of up to 50 of these vuns; and a second transmission algorithm, including:, All the VLANs of the area switch in action are considered to be able to transmit the loop detection in every second sentence Frames; and, for each one of them, one of the loop detection frames is shipped from all the ports in one of the topologies in operation, and this is done for up to 50 dozens. 2. The topological loop detection machine 1 ~ 8 0 as described in item 11 of the scope of the patent application. The time required for the topological loop is measured in frame 13. · The topology loop detection machine as described in item 10 of the scope of patent application, wherein the steps of receiving and preceding include: J receiving the loop detection and fiber modification on a feedforward port of the topology in operation If the regional switch does not send out the frame, the regional switch feeds forward the loop detection frame to the ports on the topology in operation; and § the regional switch When receiving the loop detection frame on the closed port, /, the loop detection frame and no longer feed forward the loop detection frame. 14 · The topology loop detection machine described in item 丨 0 of the scope of patent application, wherein the analysis step includes: · judging whether or not the topology loop exists, according to the loop detection frame issued 11872UV 丨 '.ptd 1229993 6. The scope of patent application-whether the port and the frame receiving the loop detection frame are both in the feedforward state; if the ports are in different ports, the area switch = Pu A part of the loop; and if the ports are the same port, the topology loop exists at the far end. 1 5 · The topology loop detection system described in item No. 丨 0 of the scope of patent application, where the action steps include: If the port is connected early, the loop detection box of the loop detection box is closed. When a remote topology loop is reached, the terminal is warned to make remedies; and, after a period of time has elapsed, the user will automatically reply to the operation. System, 2 · As stated in the application, "Topology loop detection machine described in item 15 of the scope of pre-exclusive benefits: dynamic recovery operation" makes the end user not need to access ^ 'Λ ^ -stp 11 ^ ^ ^ ^ ^ This is when the topology exchange circle "砀" is detected in the area, when the topology is: The closed loop is incorrectly turned on for the feedforward itching. Among them 1-8. Zhongli hardware is trapped-it is detected that the topology loop, and its ", such as the application: range or the first state of receipt. Among them, once the-topology loop described in the line 3 is detected Debt testing mechanism, 1lB72twf.ptd Page 25 The lost line set 'The topology loop was detected, of which 1229999 6. The scope of the patent application has two different ends of the connection line. If a VLAN translation is detected, the loop detection mechanism is detected. The VLAN assignments on the port are inconsistent. , * 垓 Topology loop, and the 2 1 · As described in item No. of the scope of the patent application, which is based on the detection of the f-loop detection mechanism between most L3 interfaces, and one of the routers allows 13 And „Bridge detection The topology changes the finger loop pain detection frame bridge of the bridge loop frame, 22. As described in the item of the scope of the patent application]; = Potential of the topology loop The area becomes * t ；; 〇Λ :::; :::::-address to reduce the CPU load. The address system port also becomes DMAC where the topology loop detection mechanism described in item 1, For the crime, the disabled port receives or feeds back the loop detection king, so that the port sends out the loop detection frame, and when the topology loop is detected, the port is closed. ^ 2 & gt 5. · The topology loop detection mechanism as described in item 1 of the scope of the patent application, >, China 4 Topology Loop Debt Testing Mechanism has nothing to do with the ability of the converter debt to test a topology loop. 2 6 · The topology loop detection mechanism described in item 1 of the scope of the patent application, wherein the topology loop detection mechanism allows any sum check / certification authentication algorithm. Page 11872twf.ptd