CN100525248C - Flow control realizing method based on physical layer multiplex - Google Patents

Abstract

The invention discloses a method for implementing flow control based on physical layer multiplexing. The physical layer multiplexing includes a MAC layer forwarding chip and a multi-level physical layer multiplexing chip. The method for implementing flow control in the present invention includes: the MAC layer forwarding chip The physical port label of the physical port is added to the flow control frame generated for the physical port, and the physical port label corresponds to the physical port one by one; the flow control frame is forwarded out of the physical port according to the physical port label. The invention enables the MAC layer forwarding chip to generate and send the flow control frame for each physical port, and realizes the physical port flow control based on the multiplexing of the physical layer.

Description

Implementation method of flow control based on physical layer multiplexing

technical field

The invention relates to a link layer flow control method in the network and communication fields, in particular to a flow control realization method based on physical layer multiplexing.

Background technique

When two physical ports of a network device are connected, each physical port receives a service data frame from the other party, and forwards and processes the service data frame according to the destination address and service characteristics of the received service data frame.

The network device sets up a receiving queue for each physical port to buffer the service data frames received by the physical port. However, if the sending rate of the peer end is always higher than the forwarding rate of the physical port for a period of time, the service data frames received after the receive queue overflows will be discarded.

Link layer flow control solves this problem through flow control frames. When the service data frames in the receiving queue of a certain physical port exceed the flow control notification threshold, the network device sends a flow control notification frame with the agreed format to the peer end, instructing the peer end to suspend sending. Take the Ethernet flow control notification frame as an example, its format is shown in the following table:

Destination MAC address source MAC address type opcode Fluid time stuffing bytes parity byte

In the above table, the destination MAC address is fixed at 0x0180c2000001; the source MAC address in the table is the MAC address of the physical port; the type protocol is specified as 0x8808, and the length is 2 bytes; the operation code protocol is specified as 0x0001, and the length is 2 bytes; The flow control time is used to inform the peer end of the pause sending time required by the physical port, and the length is 2 bytes; the length of the padding byte is 42 bytes, and the flow control frame is filled to the minimum frame length of 64 bytes of Ethernet, so that It can be sent and received normally on the Ethernet; the check byte is the check code of the flow control frame, and the length is 4 bytes.

When the service data frames in the receiving queue of the physical port are lower than the flow control termination threshold, the network device sends a flow control termination frame to the opposite end, and the opposite end starts to send service data frames. The Ethernet flow control termination frame has the same format as its flow control notification frame. When the flow control time field is 0, it is a flow control termination frame.

In the network device with the structure shown in Figure 1, the switching network chip is connected to more than one MAC layer forwarding chip, and the MAC layer forwarding chip is in one-to-one correspondence with the standard physical layer chip with the same interface rate. There is one physical port.

In the prior art, flow control is implemented in the MAC layer forwarding chip. The implementation method is that each MAC layer forwarding chip establishes a receiving queue for its corresponding physical port, and according to the aforementioned flow control mechanism, the generated flow control frame is directly sent from the corresponding The physical port sends, and interprets and executes the flow control frame received from the corresponding physical port.

The applicant disclosed a network access device based on physical layer multiplexing in the Chinese patent application with application number 200510109234.0. Please refer to Figure 2 for a schematic diagram of its structure. The switching network chip is connected to the MAC layer forwarding chip, and the MAC layer forwarding chip Connect more than one physical layer multiplexing chip. Each physical layer multiplexing chip has multiple physical ports. The physical layer multiplexing chip aggregates the services of multiple low-speed physical ports to the high-speed interface connected to the MAC layer forwarding chip. The service data frames received by each low-speed physical port are forwarded by the MAC layer forwarding chip.

It can be seen that since one MAC layer forwarding chip in a network device based on physical layer multiplexing corresponds to multiple physical ports, the flow control frames generated according to the protocol standard have the same destination MAC address, and the MAC layer forwarding chip cannot reach the corresponding physical port. , and at the same time, the MAC layer forwarding chip cannot know which physical port the flow control frame it receives corresponds to.

Contents of the invention

The purpose of the present invention is to provide a flow control implementation method, which can solve the problem that the MAC layer forwarding chip performs flow control on each physical port after the physical layer is multiplexed.

The physical layer multiplexing in the present invention includes media access control MAC layer forwarding chips and n-level physical layer multiplexing chips, n is an integer greater than or equal to 1, and the MAC layer forwarding chips and physical layer multiplexing chips at all levels are set up. The corresponding relationship between the downlink interface of the chip and the physical port label of the physical port connected to the downlink interface; the flow control implementation method based on physical layer multiplexing of the present invention comprises the following steps:

The MAC layer forwarding chip adds the physical port label of the physical port in the flow control frame generated for the physical port, and the physical port label corresponds to the physical port one by one;

According to the physical port label, the flow control frame is forwarded out of the physical port.

Optionally, the method further includes: the downlink forwarding of the flow control frame according to the physical port label is specifically:

The MAC layer forwarding chip forwards the flow control frame to the downlink interface corresponding to its physical port label;

The physical layer multiplexing chips at all levels forward the flow control frame to the downlink interface corresponding to the physical port label until the physical port corresponding to the physical port label;

Before forwarding the flow control frame out of the physical port, the method further includes: stripping the physical port label in the flow control frame.

Preferably, the physical port label includes a MAC interface label, a level 1 multiplexing label to an nth level multiplexing label, wherein the MAC interface label is the downlink interface label of the MAC layer forwarding chip connected to the physical port; the kth level The multiplexing label is the downlink interface label of the kth-level physical layer multiplexing chip connected to the physical port, where k≥1, and k≤n;

According to the physical port label, the downlink forwarding of the flow control frame out of the physical port is specifically:

The MAC layer forwarding chip strips off the MAC interface label in the flow control frame, and forwards the flow control frame to the downlink interface corresponding to the MAC interface label;

Each level of physical layer multiplexing chip strips off the kth level multiplexing label in the flow control frame, and forwards the flow control frame to the downlink interface corresponding to the kth level multiplexing label until the physical interface is forwarded; k is the The multiplexing level where the physical layer multiplexing chip is located.

Preferably, the MAC interface label and the first-level multiplexing label to the n-th level multiplexing label are arranged according to the connection sequence of the MAC layer interface chip and the first-level to n-th level physical layer multiplexing chips.

Preferably, the method further includes: MAC layer forwarding chips and physical layer multiplexing chips at all levels forward and process flow control frames with priority higher than service data frames.

Preferably, the method further includes: upstream forwarding the received flow control frame to the MAC layer forwarding chip, and adding a physical port label of its physical ingress port to the flow control frame.

Another flow control implementation method based on physical layer multiplexing provided by the present invention, the physical layer multiplexing includes a media access control MAC layer forwarding chip and an n-level physical layer multiplexing chip, n is an integer greater than or equal to 1, Establish the corresponding relationship between the downlink interface of the chip and the physical port label of the physical port connected to the downlink interface on the MAC layer forwarding chip and all levels of physical layer multiplexing chips; the method may further comprise the steps:

Receive flow control frames from physical ports;

The received flow control frame is forwarded up to the MAC layer forwarding chip, and the physical port label of the physical ingress port is added to the flow control frame, and the physical port label corresponds to the physical port one by one.

Optionally, adding a physical port label to the received flow control frame and forwarding it to the MAC layer forwarding chip is specifically:

The lowest-level physical layer multiplexing chip adds a physical port label corresponding to its physical ingress port to the flow control frame;

Forward the flow control frame with the physical port label up to the MAC layer forwarding chip.

Preferably, the physical port label includes a MAC interface label, a level 1 multiplexing label to an nth level multiplexing label, wherein the MAC interface label is the downlink interface label of the MAC layer forwarding chip connected to the physical port; the kth level The multiplexing label is the downlink interface label of the kth-level physical layer multiplexing chip connected to the physical port, where k≥1, and k≤n;

Adding a physical port label to the received flow control frame and forwarding it to the MAC layer forwarding chip is specifically:

Each level of physical layer multiplexing chip adds the downlink interface label of the downlink interface receiving the flow control frame to the flow control frame as the kth level multiplexing label of the flow control frame, and forwards the flow control frame upstream; k is the flow control frame The multiplexing level where the physical layer multiplexing chip is located;

The MAC layer forwarding chip adds the downlink interface label of the downlink interface receiving the flow control frame to the flow control frame as the MAC interface label of the flow control frame.

Preferably, the MAC interface label and the first-level multiplexing label to the n-th level multiplexing label are arranged according to the connection sequence of the MAC layer interface chip and the first-level to n-th level physical layer multiplexing chips.

Preferably, the method further includes: MAC layer forwarding chips and physical layer multiplexing chips at all levels forward and process flow control frames with priority higher than service data frames.

In the present invention, by adding the physical port label corresponding to the physical port in the flow control frame, the MAC layer forwarding chip and the physical layer multiplexing chips at all levels forward the flow control frame to the corresponding physical port according to the physical port label, so that the MAC layer The forwarding chip can generate and send flow control frames for each physical port, realizing physical port flow control based on physical layer multiplexing.

Description of drawings

FIG. 1 is a schematic structural diagram of a network device supported by an existing flow control implementation method;

FIG. 2 is a schematic structural diagram of a network device based on physical layer multiplexing;

Fig. 3 is a structural example diagram of the application environment of the present invention;

Fig. 4 is the flow chart of the method for realizing flow control described in the present invention;

FIG. 5 is a flow chart of Embodiment 1 of the flow control frame sending and receiving process in the present invention;

FIG. 6 is a flowchart of Embodiment 2 of the flow control frame sending and receiving process in the present invention.

Detailed ways

Network equipment based on physical layer multiplexing can adopt a cascaded structure of multi-level physical layer multiplexing chips. Taking the 3-level cascading as an example, its structure is shown in Figure 3. The downlink interface of a MAC layer forwarding chip is connected to multiple first-level physical layer multiplexing chips, and the downlink interface of each first-level physical layer multiplexing chip is connected to multiple second-level physical layer multiplexing chips. The downlink interface of the physical layer multiplexing chip is connected to multiple third-level physical layer multiplexing chips, and the downlink interface of the third-level physical layer multiplexing chip is a plurality of physical ports. Without loss of generality, assume that the present invention is applied to a cascaded structure with n-level physical layer multiplexing chips, wherein n is an integer greater than or equal to 1, and the physical layer multiplexing chip whose multiplexing level is k is the downlink connection of the MAC layer forwarding chip The physical layer multiplexing chip of the kth level, and the downlink interface of the physical layer multiplexing chip of the nth level is a physical port.

According to the seven-layer protocol model of OSI (Open System Interconnection, Open System Interconnection), the flow control of the physical layer is implemented at the link layer. Therefore, in the present invention, the MAC layer forwarding chip should monitor the receiving queues of all the physical ports connected to it, and generate a flow control frame for a certain physical port when flow control is required. In order to enable the flow control frame to be sent from the physical port to the opposite end of the data service frame communication with it, so as to achieve the purpose of flow control, the MAC layer forwarding chip and its downstream physical layer multiplexing chips are in the process of downlink forwarding It is necessary to determine the correct forwarding path for the generated flow control frame so that it can reach the corresponding physical port.

Similarly, after a physical port receives a flow control frame, after the physical layer multiplexing chip forwards it to the MAC layer forwarding chip step by step, the MAC layer forwarding chip needs to identify which physical port the flow control frame comes from, so as to Physical port for flow control.

In the present invention, mark the physical port associated with it by adding the physical port label in the flow control frame, thus all physical ports connected under a MAC layer forwarding chip should have different physical port labels, and the physical port and the physical port label are one by one correspond.

The flow of the flow control implementation method based on physical layer multiplexing in the present invention is shown in FIG. 4 . In step S410, the MAC layer forwarding chip establishes a receiving queue for each physical port.

In step S420, when the storage space occupied by the service data frames in the receiving queue of a certain physical port, that is, the length of the receiving queue exceeds a predetermined flow control notification threshold, the MAC layer forwarding chip generates a flow control notification frame for the physical port.

Same as in the prior art, the MAC layer forwarding chip generates a flow control notification frame according to the adopted communication protocol. For example, in Ethernet, 0x0180c2000001 is used as the destination MAC address of the flow control notification frame, and the MAC address of the physical port is used as the flow control notification frame. Indicates the source MAC address of the notification frame.

Multiple flow control notification thresholds can be set, corresponding to different flow control times in the flow control notification frame.

In step S430, when the length of the receiving queue of the physical port sending the flow control notification frame is lower than the predetermined flow control termination threshold, the MAC layer forwarding chip generates a flow control termination frame for the physical port.

If the flow control time is specified in the flow control notification frame, this step can be omitted.

In step S440, the MAC layer forwarding chip adds the physical port identifier of the physical port to the flow control frame generated by it. As mentioned above, the physical port identifier of each physical port is unique among all the physical ports connected to the MAC layer forwarding chip.

In step S450, the MAC layer forwarding chip and the physical layer multiplexing chips at all levels forward the flow control frame out of the physical port step by step according to the physical port identifier in the flow control frame. This step is the downlink forwarding process of the flow control frame.

In step S460, when a certain physical port receives the flow control frame, forward the flow control frame upstream to the MAC layer forwarding chip, and add the physical port label of the physical ingress port of the flow control frame during the forwarding process. This step is the upstream forwarding process of the flow control frame.

In step S470, after the MAC layer forwarding chip receives the flow control frame, it learns the physical port that needs flow control from the physical port label in the flow control frame, and then performs corresponding processing on the physical port according to the instruction in the flow control frame. flow control operation.

In order to have a better flow control effect, the MAC layer forwarding chip and the physical layer multiplexing chips at all levels can forward and process the flow control frame with a higher priority than the service data frame in the uplink and downlink directions. The physical layer multiplexing chip has a buffer queue for the uplink interface, and a dedicated buffer queue can be set for the flow control frame, so that the scheduling priority of the dedicated buffer queue is higher than the buffer queue used by the business data frame, and the priority of the flow control frame can be realized. Forward.

In this case, both the MAC layer forwarding chip and the physical layer multiplexing chips at all levels need to distinguish the flow control frame from the service data frame first, and the method of distinguishing the flow control frame from the service data frame is determined according to the adopted protocol. Taking Ethernet as an example, two characteristics can be used to distinguish flow control frames from service data frames. One is that the destination MAC address of the flow control frame is fixed at 0x0180c2000001; the other is that the type of the flow control frame is 0x8808.

In the present invention, the same method as the prior art is used to generate the flow control frame, interpret and execute the instructions of the received flow control frame, so as to realize the compatibility with the prior art.

Steps S410 to S450 are the process of generating a flow control frame to control the flow of the opposite end, while steps S460 to S470 are the process of receiving the flow control frame of the opposite end and performing flow control on the corresponding physical port. These two processes can be performed independently It is applied in the flow control method, and can also be used in combination in the flow control method.

When different physical port label setting methods are used, the uplink forwarding and downlink forwarding processes of flow control frames are also different. Two examples of flow control frame sending and receiving processes are provided below for illustration.

In the first embodiment of the flow control frame sending and receiving process, the physical port label remains unchanged during the flow control frame sending and receiving process. The flow of the first embodiment is shown in FIG. 5 .

In step S510, set physical port labels having a one-to-one correspondence with all physical ports. Since physical port labels are used in both uplink receiving and downlink sending, it is necessary to set the corresponding relationship between each physical port and its physical port label on the MAC layer forwarding chip, and multiplex each physical port label of the chip at the lowest physical layer. Set the physical port label of the physical port on the port.

In step S520, a corresponding relationship between its downlink interface and the physical port label of the physical port connected to the MAC layer forwarding chip through the downlink interface is established on the MAC layer forwarding chip. The downlink interface of the MAC layer forwarding chip is the interface connected to the first-level physical layer multiplexing chip.

The above corresponding relationship maps all physical port labels to all downlink interfaces of the MAC layer forwarding chip. After establishing such a mapping relationship, the MAC layer forwarding chip can know from which downlink interface a flow control frame with the physical port as the outgoing port should be forwarded from the physical port label of the physical port. Level 1 physical layer multiplexing chip.

In step S530, the corresponding relationship between its downlink interface and the physical port label connected to the physical port on the physical layer multiplexing chip through the downlink interface is established on each physical layer multiplexing chip. The downlink interface of the kth physical layer multiplexing chip is an interface connected to the (k+1)th physical layer multiplexing chip, where k is an integer greater than or equal to 1 and less than n.

Similar to step S520, the above correspondence maps all physical port labels to all downlink interfaces of each level of physical layer multiplexing chips. On each physical layer multiplexing chip, only the mapping relationship between the physical port identifiers of some physical ports connected to the physical layer multiplexing chip and its downlink interface is reserved. For the lowest-level physical layer multiplexing chip, the mapping relationship is the corresponding relationship between its physical ports and their physical port identifiers. After establishing such a mapping relationship, each physical layer multiplexing chip can know which downlink interface the flow control frame should be forwarded to from the physical port label in the downlink flow control frame.

In step S540, when the MAC layer forwarding chip generates a flow control frame for a certain physical port, and adds the physical port label of the physical port in the flow control frame, the MAC layer forwarding chip according to the corresponding relationship established in step S520 , and forward the flow control frame from the downlink interface corresponding to the physical port label therein to the first-level physical layer multiplexing chip.

In step S550, the physical layer multiplexing chips at all levels forward the flow control frame forwarded downlink, according to the corresponding relationship established in step S530, forward the flow control frame to the downlink interface corresponding to the physical port label therein, until forwarded to The lowest physical layer multiplexes the physical port of the chip.

In step S560, the physical port label in the downstream flow control frame is stripped.

In step S570, the flow control frame is forwarded out of the physical port. In this way, the flow control frame sent from the network device based on physical layer multiplexing conforms to the adopted protocol standard, and can be normally recognized and executed by other devices using the same protocol.

In step S580, after receiving the flow control frame, the physical port of the lowest-level physical layer multiplexing chip adds the physical port label of its physical ingress port to the flow control frame.

In step S590, starting from the lowest-level physical layer multiplexing chip, the flow control frame added with the physical port label is forwarded up to the MAC layer forwarding chip step by step.

When the MAC layer forwarding chip receives the flow control frame, according to the physical port label in the flow control frame, it can know which physical port the flow control frame originates from, that is, which physical port the traffic of the flow control frame should be sent to Take control.

The flow of this embodiment only involves the forwarding of the flow control frame. When combined with the flow control implementation method flow of FIG. 4, for the process of generating and sending the flow control frame, steps S510 to S530 should be performed before step S420, Steps S540 to S570 are the downlink forwarding process of the flow control frame, corresponding to step S450; for the process of receiving the flow control frame and performing flow control, steps S510 to S530 should be performed before step S460, and steps S580 to S590 are The uplink forwarding process of the flow control frame corresponds to step S460.

In the second embodiment of the flow control frame sending and receiving process, the physical port label is composed of multiple parts, including the MAC interface label, the first level multiplexing label until the nth level multiplexing label, corresponding to the MAC layer forwarding chip sending flow The downlink interface label of each downlink interface that the flow control frame needs to pass through in the process of controlling the frame to the physical port on the chip where it is located. The process of Embodiment 2 is shown in FIG. 6 .

In step S610, a one-to-one correspondence between its downlink interface and its downlink interface label is established on the MAC layer forwarding chip. The downlink interface label of the MAC layer forwarding chip is unique among all downlink interfaces of the MAC layer forwarding chip.

In step S620, a one-to-one correspondence between its downlink interface and its downlink interface label is established on each physical layer multiplexing chip. Similarly, the downlink interface label of each physical layer multiplexing chip is unique among all the downlink interfaces of the physical layer multiplexing chip. The downlink interface of the lowest-level physical layer multiplexing chip is the physical port.

In other words, the downlink interface labels in step S610 and step S620 are unique only on the chip where the downlink interface is located, and the downlink interface labels on any two chips may be the same. In this way, at least one of the MAC interface labels of any two physical ports and the multiplexing labels from level 1 to level n is different, thus ensuring that the physical port labels of all physical ports connected to the MAC layer forwarding chip are different from each other of.

In step S630, when the MAC layer forwarding chip generates a flow control frame for a certain physical port, and adds the physical port label of the physical port in the flow control frame, the MAC layer forwarding chip strips the physical port in the flow control frame MAC interface label in the label, and forward the flow control frame after the MAC interface label is stripped to the downlink interface with the MAC interface label as the downlink interface label.

In step S640, the physical layer multiplexing chip that receives the downstream flow control frame at each level strips off the kth level multiplexing label in the remaining part of the physical port label in the flow control frame, and strips off the kth level multiplexing label The flow control frame is forwarded to the downlink interface with the kth level multiplexing label as the downlink interface label, until it is forwarded to the physical port of the lowest-level physical layer multiplexing chip; where k is the multiplexing level of the physical layer multiplexing chip.

In step S650, for the received flow control frame, each level of physical layer multiplexing chip adds the downlink interface label on the physical layer multiplexing chip of the downlink interface receiving the flow control frame to the flow control frame as the flow control frame. The kth level multiplexing label of the frame, and forwards the flow control frame after adding the kth level multiplexing label; where k is the multiplexing level of the physical layer multiplexing chip.

In step S660, after the MAC layer forwarding chip receives the uplink flow control frame forwarded by the first-level physical layer multiplexing chip, add the downlink link on the MAC layer forwarding chip of the downlink interface receiving the flow control frame to the flow control frame Interface label, as the MAC interface label of the flow control frame.

In this way, the MAC layer forwarding chip can know which physical port the flow control frame comes from according to the complete physical port label in the flow control frame, that is, which physical port should control the traffic according to the flow control frame.

Same as in Embodiment 1, the flow of this embodiment only involves the forwarding of the flow control frame. When combined with the flow control implementation method flow in FIG. 4 , for the process of generating and sending the flow control frame, steps S610 to S620 should Carry out before step S420, and step S630 to step S640 are the downstream forwarding process of flow control frame, corresponding to step S450; To the process of generating and sending flow control frame, step S610 to step S620 should be carried out before step S460, and step S650 to step S660 are the upstream forwarding process of the flow control frame, corresponding to step S460.

It can be seen that in this embodiment, before the downlink forwarding of the generated flow control frame begins, the physical port label added by the MAC layer forwarding chip according to the physical port for flow control is complete. , the chip that each level of forwarding passes through strips off some of the physical port labels related to the level of forwarding, and strips off all the physical port labels before forwarding the physical port; while the upstream forwarding process of receiving flow control frames is reversed, Each forwarding chip adds a part of the physical port label related to the level of forwarding in the flow control frame according to its incoming interface. After the forwarding chip at the MAC layer, it adds the MAC interface label at the end to form a complete physical port label. Based on this, the layer forwarding chip can know the physical port that needs to be controlled by flow.

For MAC layer forwarding chips and physical layer multiplexing chips at all levels, the corresponding MAC interface label and multiplexing label of this level should be in a fixed position in the flow control frame arriving at this level of chip, so that this level of chip can be identified. For convenience, the MAC interface label and the first-level to n-level multiplexing labels can be arranged in the order of connection of the MAC layer interface chip and the first-level to n-level physical layer multiplexing chip.

In the present invention, the position of the physical port label in the flow control frame can be set by the user. For example, the physical port label can be added before the frame header of the flow control frame, and the flow control frame with a VLAN (Virtual Local Area Network, virtual local area network) label can also be added in the VLAN domain.

The present invention adds the physical port label corresponding to the physical port in the flow control frame, and indicates the physical port corresponding to the flow control frame in the case of multiplexing the physical layer to the MAC layer forwarding chip and the physical layer multiplexing chips at all levels, so that The MAC layer forwarding chip can generate and receive flow control frames for each physical port, realizing physical port flow control based on physical layer multiplexing.

The embodiments of the present invention described above are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (11)

1. A flow control implementation method based on physical layer multiplexing, wherein said physical layer multiplexing comprises a media access control MAC layer forwarding chip and an n-level physical layer multiplexing chip, and n is an integer greater than or equal to 1, characterized in that , on the MAC layer forwarding chip and the physical layer multiplexing chip at all levels, the corresponding relationship between the downlink interface of the chip and the physical port label of the physical port connected to the downlink interface is established; the flow control implementation method includes the following steps: The MAC layer forwarding chip adds the physical port label of the physical port in the flow control frame generated for the physical port, and the physical port label corresponds to the physical port one by one; According to the physical port label, the flow control frame is forwarded out of the physical port. 2. The method for implementing flow control based on physical layer multiplexing as claimed in claim 1, wherein the downstream forwarding of the flow control frame according to the physical port label is specifically: The MAC layer forwarding chip forwards the flow control frame to the downlink interface corresponding to its physical port label; The physical layer multiplexing chips at all levels forward the flow control frame to the downlink interface corresponding to the physical port label until the physical port corresponding to the physical port label; Before forwarding the flow control frame out of the physical port, the method further includes: stripping the physical port label in the flow control frame. 3. The flow control implementation method based on physical layer multiplexing as claimed in claim 1, wherein the physical port label comprises a MAC interface label, the first level multiplexing label to the nth level multiplexing label, wherein the MAC interface The label is the downlink interface label of the MAC layer forwarding chip connected to the physical port; the kth level multiplexing label is the downlink interface label of the kth level physical layer multiplexing chip connected to the physical port, where k≥1, and , k≤n; According to the physical port label, the downlink forwarding of the flow control frame out of the physical port is specifically: The MAC layer forwarding chip strips off the MAC interface label in the flow control frame, and forwards the flow control frame to the downlink interface corresponding to the MAC interface label; Each level of physical layer multiplexing chip strips off the kth level multiplexing label in the flow control frame, and forwards the flow control frame to the downlink interface corresponding to the kth level multiplexing label until the physical interface is forwarded; k is the The multiplexing level where the physical layer multiplexing chip is located. 4. The flow control implementation method based on physical layer multiplexing as claimed in claim 3, characterized in that: the MAC interface label and the 1st level multiplexing label to the nth level multiplexing label are in accordance with the MAC layer interface chip and the 1st level multiplexing label The connection sequence of physical layer multiplexing chips from level to nth level is arranged. 5. The flow control implementation method based on physical layer multiplexing according to any one of claims 1 to 4, characterized in that the method further comprises: MAC layer forwarding chips and physical layer multiplexing chips at all levels to be higher than business Priority forwarding of data frames and processing of flow control frames. 6. The flow control implementation method based on physical layer multiplexing as claimed in claim 1, wherein the method further comprises: forwarding the received flow control frame uplink to the MAC layer forwarding chip, and adding The physical port label of its physical ingress port. 7. A flow control implementation method based on physical layer multiplexing, said physical layer multiplexing comprises a media access control MAC layer forwarding chip and an n-level physical layer multiplexing chip, and n is an integer greater than or equal to 1, characterized in that , on the MAC layer forwarding chip and the physical layer multiplexing chip at all levels, the corresponding relationship between the downlink interface of the chip and the physical port label of the physical port connected to the downlink interface is established; the flow control implementation method includes the following steps: Receive flow control frames from physical ports; The received flow control frame is forwarded up to the MAC layer forwarding chip, and the physical port label of the physical ingress port is added to the flow control frame, and the physical port label corresponds to the physical port one by one. 8. as claimed in claim 7, based on the flow control implementation method of physical layer multiplexing, it is characterized in that, Adding a physical port label to the received flow control frame and forwarding it to the MAC layer forwarding chip is specifically: The lowest-level physical layer multiplexing chip adds a physical port label corresponding to its physical ingress port to the flow control frame; Forward the flow control frame with the physical port label up to the MAC layer forwarding chip. 9. The flow control implementation method based on physical layer multiplexing as claimed in claim 7, wherein the physical port label comprises a MAC interface label, the first level multiplexing label to the nth level multiplexing label, wherein the MAC interface The label is the downlink interface label of the MAC layer forwarding chip connected to the physical port; the kth level multiplexing label is the downlink interface label of the kth level physical layer multiplexing chip connected to the physical port, where k≥1, and , k≤n; Adding a physical port label to the received flow control frame and forwarding it to the MAC layer forwarding chip is specifically: Each level of physical layer multiplexing chip adds the downlink interface label of the downlink interface receiving the flow control frame to the flow control frame as the kth level multiplexing label of the flow control frame, and forwards the flow control frame upstream; k is the flow control frame The multiplexing level where the physical layer multiplexing chip is located; The MAC layer forwarding chip adds the downlink interface label of the downlink interface receiving the flow control frame to the flow control frame as the MAC interface label of the flow control frame. 10. The flow control implementation method based on physical layer multiplexing as claimed in claim 9, characterized in that: the MAC interface label and the first level multiplexing label to the nth level multiplexing label are in accordance with the MAC layer interface chip and the first level The connection sequence of physical layer multiplexing chips from level to nth level is arranged. 11. The flow control implementation method based on physical layer multiplexing according to any one of claims 7 to 10, characterized in that, the method further comprises: MAC layer forwarding chips and physical layer multiplexing chips at all levels to be higher than business Priority forwarding of data frames and processing of flow control frames.

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