CN107566143B

CN107566143B - Longitudinal stacking discovery method and device

Info

Publication number: CN107566143B
Application number: CN201610512630.6A
Authority: CN
Inventors: 吕娜; 杨国芳; 曹淑玲
Original assignee: Shenzhen Zte Technical Service Co ltd
Current assignee: Shenzhen ZTE Technical Service Co.,Ltd.
Priority date: 2016-06-30
Filing date: 2016-06-30
Publication date: 2022-02-25
Anticipated expiration: 2036-06-30
Also published as: CN107566143A

Abstract

The embodiment of the invention provides a method and a device for discovering longitudinal stacking.A port expansion device obtains unique identification information of the port expansion device and encapsulates the unique identification information into a link layer discovery protocol message; the link layer discovery protocol message is sent to the control network bridge in a timing cycle mode, so that the control network bridge monitors the online state of the port expansion equipment according to the unique identification information.

Description

Longitudinal stacking discovery method and device

Technical Field

The present invention relates to the field of communications, and in particular, to a method and an apparatus for discovering a vertical stack.

Background

With the development of cloud computing and the rapid increase of virtual machines, the data centers of enterprises also have some management difficulties, and the development of network technology must adapt to the new trend of virtualization technology. Therefore, the IEEE organization proposes a series of new 802.1 standards for new technologies such as data center virtual machine migration, including 802.1Qau (congestion notification), 802.1Qaz (enhanced transport selection), 802.1Qbb (priority-based flow control), 802.1Qbg (edge virtual bridge), 802.1BR (virtual bridge interface extension), and the like. The vertical stacking technique is implemented based on the 802.1BR standard. As shown in fig. 1, the vertical stack generally includes 2 important parts CB (control Bridge) and PE (Port Extended). The longitudinal stacking is realized by deploying a remotely interactive switch as a CB, deploying an entity access switch or a software virtual switch as a PE, and establishing a plurality of E-channels (Extended channels) between the CB and the PE by setting a cascade port of the CB and an uplink port of the PE so as to realize the interaction between the CB and the PE. And the vertical stack uses LLDP (Link Layer Discovery Protocol) message for discovering each other of CB and PE according to 802.1BR standard; the CB discovers the PE Port through a PE CSP (Port extension Control and Status Protocol) message, and creates a corresponding BEP Port, thereby constructing a vertical stack network. In a stacked system, 200 to 400 PEs can be linked under each CB, and there are more than ten thousand expansion ports, so operations such as viewing device attributes and configuring expansion ports need to depend on a stable topology network structure. However, in the prior art, since the 802.1BR protocol is applied to identify the PE device by using the MAC address, if the PE user reconfigures the MAC address, the topologram network considers that the original PE device is offline and the new PE device is online, which brings inconvenience to management; and the online state of the PE is modified, so that the CB-PFU port vibrates, all PE equipment under the port is continuously on-line and off-line, and the system is unstable.

Disclosure of Invention

The method and the device for discovering the longitudinal stack mainly solve the technical problem that a management mode for managing the PE equipment is unreasonable in the prior art, so that a system is unstable.

To solve the above technical problem, an embodiment of the present invention provides a method for discovering a vertical stack, including:

acquiring unique identification information of the port expansion equipment, and packaging the unique identification information into a link layer discovery protocol message;

and periodically and circularly sending the link layer discovery protocol message to the control network bridge.

The embodiment of the invention also provides a longitudinal stacking discovery method, which comprises the following steps:

receiving link layer discovery protocol messages with unique identification information sent by each port expansion device at regular time, and analyzing and acquiring the unique identification information in the messages;

and determining the current state of each port expansion device according to the change condition of the received unique identification information in each timing period.

An embodiment of the present invention further provides a device for discovering a vertical stack, including:

the unique identification information processing module is used for acquiring the unique identification information of the port expansion equipment and packaging the unique identification information into a link layer discovery protocol message;

and the sending module is used for sending the link layer discovery protocol message to the control network bridge in a timing cycle manner.

the message processing module is used for regularly receiving the link layer discovery protocol message with the unique identification information sent by each port expansion device, analyzing and acquiring the unique identification information in the message;

and the state setting module is used for determining the current state of each port expansion device according to the change condition of the received unique identification information in each timing period.

An embodiment of the present invention further provides a computer storage medium, where computer-executable instructions are stored in the computer storage medium, and the computer-executable instructions are used to execute any one of the foregoing vertical stack discovery methods.

The invention has the beneficial effects that:

according to the method, the device and the computer storage medium for discovering the longitudinal stack, provided by the embodiment of the invention, the port expansion equipment obtains the unique identification information of the port expansion equipment and encapsulates the unique identification information into a link layer discovery protocol message; the method comprises the steps of sending a link layer discovery protocol message to a control network bridge in a timing cycle mode, enabling the control network bridge to monitor the online state of the port expansion equipment according to the unique identification information, and compared with the prior art that a PE sends an MAC address of the PE to a CB (chip card), the CB judges the online state of the PE according to whether the MAC address of the PE changes or not, the actual online state of the PE cannot be accurately obtained through the management mode, the PE is unreasonably managed, the system is unstable, the longitudinal stacking discovery method enables the management of the system on the port expansion equipment to be more reasonable, and the stability of the system is improved.

Drawings

FIG. 1 is a vertical stacking topology of any of the embodiments of the present invention;

FIG. 2 is a flowchart of a vertical stack discovery method according to a first embodiment of the present invention;

fig. 3 is a schematic diagram of an LLDP message according to a first embodiment of the present invention;

FIG. 4 is a flowchart of a vertical stack discovery method according to a second embodiment of the present invention;

FIG. 5 is a schematic diagram of a vertical stack discovery apparatus according to a third embodiment of the present invention;

FIG. 6 is a schematic diagram of a vertical stack discovery apparatus according to a fourth embodiment of the present invention;

fig. 7 is a schematic diagram of a vertical stack discovery method according to a fifth embodiment of the present invention.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

The first embodiment is as follows:

the present embodiment provides a method for discovering a vertical stack, please refer to fig. 2, which specifically includes:

step S201, obtaining the unique identification information of the port expansion device, and encapsulating the unique identification information into a link layer discovery protocol message.

Specifically, to ensure that the port expansion device PE can be accurately managed, the CB needs to acquire unique identification information that can uniquely identify the PE, and then determines whether the PE is online or offline according to the unique identification information. The PE needs to report its unique identification information to the CB. Specifically, the PE obtains its unique identification information from the bottom layer, encapsulates the unique identification information in an LLDP message, establishes communication with the CB, and sends the LLDP message to the CB.

Further, the unique identification information is serial number information solidified in the port expansion device PE; encapsulating the unique identification information into a link layer discovery protocol message comprises: and defining a field name of attribute information for uniquely identifying the port expansion equipment in the link layer discovery protocol LLDP message, and storing the serial number information as a value into the link layer discovery protocol message.

Specifically, in practical application, the unique identification information of the PE may be serial number information of the PE, and the serial number information is solidified in the PE after the PE leaves a factory, and is used to uniquely identify one PE device. The PE encapsulates the serial number information in the LLDP message, specifically needs to define a field name uniquely identifying the PE attribute information in the LLDP message, the new field name is subtype, and stores the serial number information as a Value in a Value field in the LLDP message. The format of the LLDP packet is shown in fig. 3, and specifically includes: TLV type: the Value is fixed to 127 (FE hexadecimal), and expressed as an organization definition TLV (Type Length Value ). Length: the length of TLV information string, i.e., the length of a string starting from OUI (organization unique identifier) to the end of value. OUI: the value is fixed to 00-19-0C (hexadecimal). Subtype: the organized defined subtype is a newly defined 8-bit subtype number and is used for identifying a field which stores a serial number capable of uniquely identifying one device in a message. Value: storing attribute information uniquely identifying a piece of PE equipment, such as a serial number of the PE equipment, such as the aforementioned serial number: 18446744073709551615. the TLV type and TLV information string in the LLDP message belong to the TLV header part of the LLDP message, and the OUI, Subtype and Value belong to the TLV information string part of the LLDP message.

Step S202, the link layer discovery protocol message is sent to the control network bridge in a timing cycle mode.

Specifically, after the unique identification information of the PE is encapsulated in the LLDP message, the LLDP message is sent to the CB, and in order to enable the CB to determine the online state of the PE through the LLDP message containing the unique identification information of the PE, the PE needs to periodically send the LLDP message to the CB and keep alive through the LLDP message.

It should be understood that, in this embodiment, the unique identification information of the PE may be, besides the serial number information of the PE, other information that can uniquely identify the PE and is not changed with external factors, which is not specifically limited in this embodiment. In addition, the PE sends its unique identification information through the LLDP message, and may also send some other attribute information to the CB through the LLDP message.

In the method for discovering a vertical stack provided in this embodiment, a port expansion device obtains unique identification information of the port expansion device and encapsulates the unique identification information into a link layer discovery protocol message; the method comprises the steps of sending a link layer discovery protocol message to a control network bridge in a timing cycle mode, enabling the control network bridge to monitor the online state of the port expansion equipment according to the unique identification information, and managing a corresponding topology network.

Example two:

the present embodiment provides a method for discovering a vertical stack, please refer to fig. 4, which specifically includes:

step S401, periodically receiving the link layer discovery protocol message with the unique identification information sent by each port expansion device, and analyzing and acquiring the unique identification information in the message.

Specifically, the CB establishes communication with the PE, receives an LLDP message periodically sent by the PE device at a fixed time, and then obtains unique identification information of the PE device stored in the LLDP message by parsing the LLDP message. Specifically, the CB receives an LLDP packet reported by the PE, acquires a field storing the unique identifier information from the Subtype field, and then reads the stored unique identifier information from the Value according to the field. The unique identification information may specifically be serial number information of the PE, or may be other identification information that can be used to uniquely identify the PE.

Further, in the method for discovering a vertical stack provided in this embodiment, the method further includes: and establishing and dynamically maintaining a port expansion equipment topology network according to the attribute information and the unique identification information of each port expansion equipment with the current state being online.

Specifically, after receiving an LLDP message reported by a PE, a CB establishes and maintains a topology network with the PE according to the LLDP message, where the LLDP message includes attribute information and unique identification information of the PE, and the CB establishes and dynamically maintains the topology network of the PE whose current state is online according to the attribute information and the unique identification information, which specifically includes: if the CB is the LLDP message containing the unique PE identification information of the PE device received for the first time, the unique PE identification information and other attribute information need to be stored in the topology network; if the CB receives the PE for the second time or the Xth time, the state information and others of the PE in the topology network are adjusted according to the received LLDP message.

Step S402, determining the current state of each port expansion device according to the change condition of the received unique identification information in each timing period.

Specifically, the CB maintains the PE topology network according to the attribute information and the unique identification information of each port expansion device whose current state is online, including: determining the current state of each port expansion device according to the change condition of the received unique identification information in each timing period, which specifically comprises the following steps: when the received unique identification information is not in the port expansion equipment topology network, setting the current state of the port expansion equipment corresponding to the unique identification information as on-line, and storing the attribute information and the unique identification information of the port expansion equipment into the port expansion equipment topology network; when the received unique identification information is in the port expansion equipment topology network, judging that the current state of the port expansion equipment corresponding to the unique identification information is online; and for the unique identification information in the port expansion device topology network, when the unique identification information is not received in the current period and the previous continuous N periods, judging that the current state of the port expansion device corresponding to the unique identification information is offline, and deleting the unique identification information and the attribute information of the port expansion device corresponding to the unique identification information from the port expansion device topology network, wherein N is a positive integer greater than or equal to 0. After the CB receives an LLDP message which is sent by the PE and contains the PE unique identification information for the first time, if the CB senses that the PE is on line at the moment, the PE equipment is identified to be on line, the unique identification information of the PE is extracted according to the subtype number specified by the LLDP message, the unique identification information is stored in a topology network structure, and other attribute information of the PE is also stored in a topology network. And then periodically receiving an LLDP message sent by the PE, extracting the unique identification information of the PE from the LLDP message, comparing the unique identification information with the unique identification information stored in the topology network structure, if the unique identification information is consistent with the unique identification information stored in the topology network structure, judging that the PE is online, and keeping the online identification of the PE unchanged. In addition, a threshold value for judging that the PE is not on-line may be set, if the number of times that the CB continuously does not receive the LLDP message reported by the PE reaches the threshold value, it is judged that the PE board is not on-line, and if it is determined that the PE board is off-line, corresponding off-line processing is performed, where the off-line processing is related information of the PE board, including unique identification information, presence information, and other attribute information, which is stored in the topology network, deleted from the topology network. The threshold is specifically the sum of the current period and N consecutive periods before the current period, where N may be 0, or may be other positive integers such as 1.

In the method for discovering a vertical stack provided by this embodiment, the CB receives regularly a link layer discovery protocol packet with its unique identification information sent by each port expansion device, and parses and acquires the unique identification information in the packet; the current state of each port expansion device is determined according to the change condition of the received unique identification information in each timing period, so that the control network bridge monitors the online state of the port expansion device according to the unique identification information and manages the corresponding topology network.

Example three:

referring to fig. 5, the longitudinal stack discovery apparatus 5 specifically includes: the system comprises a unique identification information processing module 51 and a sending module 52, wherein the unique identification information processing module 51 is used for acquiring unique identification information of the port expansion device and packaging the unique identification information into a link layer discovery protocol message; the sending module 52 is configured to send the link layer discovery protocol packet to the controlling bridge in a timing cycle.

Specifically, in order to ensure that the CB can accurately manage the port expansion device PE, unique identification information that can uniquely identify the PE needs to be acquired, and then whether the PE is online or offline is determined by the unique identification information. The PE needs to report its unique identification information to the CB. Specifically, the PE obtains the unique identifier information from the bottom layer through the unique identifier information processing module 51 in the vertical stack discovery device 5, encapsulates the unique identifier information in the LLDP message, establishes communication with the CB, and sends the LLDP message to the CB.

Further, the unique identification information processing module 51 is further configured to: and defining a field name for uniquely identifying the attribute information of the port expansion equipment in the link layer discovery protocol message, and storing the serial number information as a value into the link layer discovery protocol message. That is, the unique identifier processing module 51 stores the unique identifier of the PE in the LLDP message, specifically, stores the storage location of the unique identifier in the LLDP message in the new subtype field, and then stores the unique identifier as a Value in the Value field in the LLDP message.

Further, the unique identification information in this embodiment may specifically be serial number information solidified in the PE, or may also be other identification information that can uniquely identify the PE, which is not specifically limited in this embodiment. In addition, the vertical stack discovery apparatus provided in this embodiment may be specifically configured in the PE, and configured to acquire the unique identification information and the attribute information of the PE and report the information to the CB.

The sending module 52 sends the LLDP packet to the control bridge in a timing cycle, which specifically includes: after the unique identification information of the PE is encapsulated in the LLDP message, the LLDP message is sent to the CB, and in order to enable the CB to determine the online state of the PE through the LLDP message containing the unique identification information of the PE, the PE needs to periodically send the LLDP message to the CB, and keep alive through the LLDP message.

In the longitudinal stack discovery apparatus provided in this embodiment, the unique identification information of the port expansion device where the apparatus is located is obtained, and the unique identification information is encapsulated in a link layer discovery protocol message; and periodically and circularly sending the link layer discovery protocol message to the control network bridge, so that the control network bridge monitors the online state of the port expansion equipment according to the unique identification information and manages the corresponding topology network, the system can manage the port expansion equipment more reasonably, and the stability of the system is improved.

Example four:

referring to fig. 6, the longitudinal stack discovery apparatus 6 specifically includes: the system comprises a message processing module 61 and a state setting module 62, wherein the message processing module 61 is used for regularly receiving link layer discovery protocol messages with unique identification information sent by each port expansion device, analyzing and acquiring the unique identification information in the messages; the state setting module 62 is configured to determine a current state of each port expansion device according to a change of the unique identification information received in each timing cycle. The longitudinal stack finding means 6 are arranged in particular in the CB.

Specifically, the CB establishes communication with the PE, receives, at regular time, an LLDP message periodically sent by the PE device through the message processing module 61 in the vertical stack discovery apparatus 6, and then obtains, from the LLDP message, unique identification information of the PE device stored in the LLDP message by parsing. Specifically, the CB receives an LLDP packet reported by the PE, acquires a field storing the unique identifier information from the Subtype field, and then reads the stored unique identifier information from the Value according to the field. The unique identification information may specifically be serial number information of the PE, or may be other identification information that can be used to uniquely identify the PE.

Referring to fig. 6, the vertical stack discovery apparatus 6 provided in this embodiment further includes a topology network maintenance module 63, where the topology network maintenance module 63 is configured to establish and dynamically maintain a port expansion device topology network according to the attribute information and the unique identification information of each port expansion device whose current state is online.

Specifically, after the CB receives the LLDP packet reported by the PE through the packet processing module 61, the topology network maintenance module 63 establishes and maintains a topology network with the PE according to the LLDP packet, where the LLDP packet includes attribute information and unique identification information of the PE, and the CB establishes and dynamically maintains the topology network of the PE whose current state is online according to the attribute information and the unique identification information, which specifically includes: if the CB is the LLDP message containing the unique PE identification information of the PE device received for the first time, the unique PE identification information and other attribute information need to be stored in the topology network; if the CB receives the PE for the second time or the Xth time, the state information and others of the PE in the topology network are adjusted according to the received LLDP message.

The status setting module 62 provided in this embodiment is further configured to: when the received unique identification information is not in the port expansion equipment topology network, setting the current state of the port expansion equipment corresponding to the unique identification information as on-line, and storing the attribute information and the unique identification information of the port expansion equipment into the port expansion equipment topology network; when the received unique identification information is in the port expansion equipment topology network, judging that the current state of the port expansion equipment corresponding to the unique identification information is online; and for the unique identification information in the port expansion device topology network, when the unique identification information is not received in the current period and the previous continuous N periods, judging that the current state of the port expansion device corresponding to the unique identification information is offline, and deleting the unique identification information and the attribute information of the port expansion device corresponding to the unique identification information from the port expansion device topology network, wherein N is a positive integer greater than or equal to 0. That is, after the message processing module 61 receives the LLDP message containing the PE unique identifier information sent by the PE for the first time, if the CB senses that the PE is online, the status setting module 62 determines that the PE device is online, then the CB identifies the PE device as an online status, extracts the PE unique identifier information according to the subtype number specified by the LLDP message, stores the unique identifier information in the topology network, and also stores other attribute information of the PE in the topology network. Then the message processing module 61 periodically receives the LLDP message sent by the PE, extracts the unique identification information of the PE from the LLDP message, and the state setting module 62 compares the unique identification information with the unique identification information stored in the topologue network structure, if the unique identification information is consistent with the unique identification information stored in the topologue network structure, the PE is determined to be online, and the online identification of the PE is kept unchanged. In addition, a threshold value for determining that the PE is not on-line may be set, if the number of times that the CB continuously receives the LLDP packet reported by the PE reaches the threshold value, the state setting module 62 determines that the PE board is not on-line, and if it is determined that the PE board is off-line, performs corresponding off-line processing, where the off-line processing is related information of the PE board, including unique identification information, presence information, and other attribute information, which is stored in the topology network, deleted from the topology network. The threshold is specifically the sum of the current period and N consecutive periods before the current period, where N may be 0, or may be other positive integers such as 1.

The longitudinal stacking discovery device provided by this embodiment is arranged on a CB, so that the CB regularly receives link layer discovery protocol packets with unique identification information thereof sent by each port expansion device, and analyzes and acquires the unique identification information in the packets; and determining the current state of each port expansion device according to the change condition of the received unique identification information in each timing period. The control network bridge monitors the online state of the port expansion equipment according to the unique identification information and manages the corresponding topology network, so that the system can manage the port expansion equipment more reasonably, and the stability of the system is improved.

Example five:

the embodiment provides a method for discovering vertical stacking aiming at the problem of unreasonable topology network management in the prior art, please refer to fig. 7, which specifically includes:

step S701, a vertical stack network of the PE and the CB is established.

Specifically, the LLDP message is used between the PE and the CB for discovering the CB and the PE mutually, then the CB discovers the port of the PE through the CSP message of the PE, and creates a corresponding BEP port, thereby constructing a vertical stack network, and the PE and the CB can interact through an extension channel between the PE and the CB.

In step S702, the PE obtains its serial number information and sends it to the CB.

Specifically, the PE obtains its serial number information from the bottom layer, encapsulates the serial number information in an LLDP message, and then sends the LLDP message to the CB. Serial number information of a PE is a unique identifier of the PE, and the serial number information may specifically be a serial number of a PE device, where the serial number is a 64-bit numerical value, and the serial number is solidified in the PE device after the device leaves a factory, and is used to uniquely identify a PE, and the serial number is, for example, 18446744073709551615. After the PE acquires the serial number, the acquired serial number is encapsulated in an LLDP message.

Further, in this embodiment, the PE sends the LLDP packet including the sequence number information to the CB periodically, that is, the PE periodically sends the sequence number information to the CB for keeping alive.

In the LLDP packet provided in this embodiment, a new subtype needs to be defined in the LLDP packet, and is used to store the added sequence number field. The format of the redefined LLDP packet is as shown in the first embodiment, where a subtype identifier message stores a field capable of uniquely identifying a serial number of a device, and a Value stores serial number information uniquely identifying a piece of PE device, such as the serial number: 18446744073709551615.

in step S703, the CB receives the PE sequence number information sent by the PE, and determines the status of the PE according to the sequence number information.

Specifically, after the CB receives the LLDP packet containing the PE serial number information sent by the PE for the first time, if the CB senses that the PE is online at this time, the PE device is identified as online, the serial number information of the PE is extracted according to the subtype number specified by the LLDP packet, and the serial number information is stored in the topology network structure. And then periodically receiving an LLDP message sent by the PE, extracting the serial number information of the PE from the LLDP message, comparing the serial number information with the serial number information stored in the topological network structure, if the serial number information is consistent with the serial number information, judging that the PE is online, and keeping the online identification of the PE unchanged. In addition, a threshold value for judging that the PE is not on-line can be set, if the number of times that the CB continuously does not receive the LLDP reported by the PE reaches the threshold value, the CB judges that the PE single board is not on-line, and if the CB determines that the PE single board is off-line, corresponding off-line processing is carried out. The threshold may specifically be any positive integer greater than or equal to 1, such as 3 or 5.

Step S704, the PE in the offline state executes corresponding offline processing operation.

Specifically, after an original online PE goes offline, corresponding offline processing is performed on the PE, that is, the stored relevant information of the PE board, including serial number information, presence information, and the like of the board, is deleted from the topology network.

In the method for discovering a vertical stack provided in this embodiment, the method further includes: the method provides a network management query interface for a user, and the user can query the related attribute information of the PE or the expansion port in the topological network through the network management query interface, so that convenience is brought to the application of the system. And the aforementioned threshold value can be adjusted by the user as the case may be.

In the method for discovering vertical stack provided by this embodiment, the CB determines the online status of the PE device by detecting whether the unique identifier of the PE device is received, and compared with the prior art that the online status of the PE device is determined by the MAC address of the PE device, the online status of the PE device can be known more accurately, so that the system manages the PE device more conveniently and reasonably; and the problem that when the MAC address of the PE equipment is changed, the state information of the PE equipment is continuously changed, so that the CB-PFU port vibrates, all the PE equipment under the port is continuously on-line and off-line, and the stability of a system topology network is influenced is solved, and the stability of the system is improved.

It will be apparent to those skilled in the art that the modules or steps of the embodiments of the invention described above may be implemented in a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented in program code executable by a computing device, such that they may be stored on a computer storage medium (ROM/RAM, magnetic disk, optical disk) and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.

The foregoing is a more detailed description of embodiments of the present invention, and the present invention is not to be considered limited to such descriptions. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. A vertical stack discovery method, comprising:

the link layer discovery protocol message is sent to the control network bridge in a timing cycle manner, so that the control network bridge can establish and dynamically maintain a port expansion device topology network according to the attribute information and the unique identification information of each port expansion device which is on-line in the current state,

the control network bridge determines the current state of each port expansion device according to the change condition of the unique identification information received in each timing period, and the determination comprises the following steps:

when the received unique identification information is not in the port expansion equipment topological network, setting the current state of the port expansion equipment corresponding to the unique identification information as on-line, and storing the attribute information and the unique identification information of the port expansion equipment into the port expansion equipment topological network;

when the received unique identification information is in the port expansion equipment topology network, judging that the current state of the port expansion equipment corresponding to the unique identification information is online;

and for the unique identification information in the port expansion device topology network, when the unique identification information is not received in the current period and the previous continuous N periods, judging that the current state of the port expansion device corresponding to the unique identification information is offline, and deleting the unique identification information and the attribute information of the port expansion device corresponding to the unique identification information from the port expansion device topology network, wherein N is a positive integer greater than or equal to 0.

2. The method of claim 1, wherein the unique identification information is serial number information that is solidified in a port expansion device; the encapsulating of the unique identification information into a link layer discovery protocol message includes: defining a field name of attribute information uniquely identifying port extension equipment in a link layer discovery protocol message, and storing the serial number information as a value in the link layer discovery protocol message.

3. A vertical stack discovery method, comprising:

determining the current state of each port expansion device according to the change condition of the unique identification information received in each timing period,

the longitudinal stacking method further comprises: establishing and dynamically maintaining a port expansion device topology network according to the attribute information and the unique identification information of each port expansion device which is on-line in the current state,

the determining the current state of each port expansion device according to the change condition of the unique identification information received in each timing period includes:

4. A longitudinal stack discovery apparatus comprising:

a sending module, configured to send the link layer discovery protocol packet to the controlling bridge in a timing cycle manner, so that the controlling bridge can establish and dynamically maintain a port expansion device topology network according to the attribute information and the unique identification information of each port expansion device in an online state,

5. The vertical stack discovery apparatus according to claim 4, wherein said unique identification information is serial number information solidified in a port expansion device;

the unique identification information processing module is further configured to: defining a field name of attribute information uniquely identifying port extension equipment in a link layer discovery protocol message, and storing the serial number information as a value in the link layer discovery protocol message.

6. A longitudinal stack discovery apparatus comprising:

the state setting module is used for determining the current state of each port expansion device according to the change condition of the unique identification information received in each timing period;

the longitudinal stack discovery apparatus further includes: the system comprises a topology network maintenance module, a port expansion device topology network management module and a port expansion device topology network management module, wherein the topology network maintenance module is used for establishing and dynamically maintaining a port expansion device topology network according to the attribute information and the unique identification information of each port expansion device which is on-line in the current state;

the state setting module is further configured to: