CN101232444A - Hash conflict resolution method, device and switching equipment with the device - Google Patents

Abstract

The invention discloses a hash conflict resolution method, which detects the hash conflict of the MAC address during the learning process of the MAC address, and saves the conflict MAC address in the conflict MAC address table in the conflict table module outside the address table module; for the purpose The message whose address is a conflicting MAC address is forwarded at a unicast wire speed according to the conflicting MAC address table. The invention also discloses a hash conflict resolution device and a switching device with the device. With the hash conflict resolution method of the present invention, the message whose destination address is a conflicting MAC address can be forwarded at a unicast wire speed, thereby improving the utilization rate of port bandwidth.

Description

Hash conflict resolution method, device and switching equipment with the device

technical field

The invention relates to a communication technology, in particular to a MAC (media access control, media access control) address hash (HASH) conflict resolution method, device and switching equipment with the device.

Background technique

The switch learns the source MAC address of the message, establishes a forwarding table including SA (SourceAddress, source MAC address), VLAN (Virtual Local Area Network, virtual local area network) ID, and Port (port), and realizes the report according to the table. Unicast forwarding of text. The MAC address table initially stores MAC addresses in the structure of a sequential table, as shown in Table 1. In this way, when the MAC address table changes, that is, when adding or deleting MAC addresses, because the order of the MAC address table must be maintained, the MAC address table will A movement of table entries occurs. When the capacity of the MAC address table is large, the efficiency is relatively low due to the complexity of table entry movement and search.

Table 1

MAC1 MAC2 MAC3 ... MACn-1 MACn

In later switch chips, the MAC address table is stored in a hash table structure. First, determine the depth of the hash bucket, and then divide the capacity of the entire MAC address table by the depth of the hash bucket to obtain the number of required hash buckets. Each hash bucket has its own unique number, which is still stored sequentially inside the hash bucket. When learning the MAC address, a certain algorithm will be used according to the SA and VLAN ID to obtain the number of the hash bucket, and the MAC address will be stored in the bucket. This can greatly improve the efficiency of MAC address addition, deletion and search, but it also creates a problem of hash collision. As shown in Table 2, Bucket-1 is full, then other MAC addresses mapped to this bucket, such as MAC1-5, cannot be stored, although there is still free space in other hash buckets at this time.

Table 2

Bucket-1 Bucket-2 ... Bucket-N MAC1-1 MAC2-1 ... MACN-1 MAC1-2 MAC2-2 MACN-2 MAC1-3 MACN-3 MAC1-4

As shown in Figure 1, in the prior art, the process of packet forwarding through MAC address learning, taking the packet receiving SA as MAC-A from port 1 as an example, includes the following steps in sequence:

Step S10: receiving a message from port 1;

Step S20: first parse out the source address MAC-A of the message;

Step S30: performing SA-based MAC address learning;

Step S40: Perform hash calculation on MAC-A or perform hash calculation on a combination of MAC-A and its related information (such as VLANID);

Step S50: Determine whether a hash conflict occurs; if a hash conflict occurs, proceed to step S70; if no hash conflict occurs, proceed to step S80;

Step S70: MAC-A cannot be added to the MAC address table because of a hash collision, therefore, the message is forwarded to all ports in the VLAN in a broadcast manner; the process of message forwarding through MAC address learning ends.

Step S80: Add MAC-A to the MAC address table;

Step S90: The destination address is MAC-A and is forwarded to port 1 in unicast mode; the process of forwarding the message through MAC address learning ends;

It can be seen from the above process that when learning a MAC address, if the hash bucket to which the MAC address is mapped is found to be full, then although there is still free space in the MAC address table, the MAC address cannot be stored, resulting in the following The packet whose MAC address is DA is broadcast in the VLAN, occupying the effective bandwidth of other ports. In the worst case, all MAC addresses in the network are mapped to the same hash bucket, and a large number of unknown unicast packets will be broadcast in the VLAN on the network, resulting in a great waste of network bandwidth.

Contents of the invention

Aiming at the problem in the prior art that when a MAC address hash conflict occurs, the unicast message whose destination address is the conflicting MAC address cannot be unicast forwarded, the purpose of the present invention is to provide a hash conflict resolution method without switching The additional support of the chip hardware realizes the unicast wire-speed forwarding of the message with the conflicting MAC address as the destination address.

Another object of the present invention is to provide a hash conflict resolution device for implementing the MAC address hash conflict resolution method of the present invention.

Another object of the present invention is to provide a switching device with the hash conflict resolution device of the present invention.

To achieve the above object, the technical scheme of the present invention is as follows:

A hash conflict resolution method, comprising the following steps:

Step S100: performing MAC address hash collision detection on the learned MAC address during the MAC address learning process;

Step S200: When a hash conflict is detected, save the conflicting MAC address in which the hash conflict occurs in a conflicting MAC address table in a conflict table module other than the address table module;

Step S300: When receiving a message with the conflicting MAC address as the destination address, perform unicast wire-speed forwarding on the message according to the conflicting MAC address table.

The hash conflict resolution method of the present invention, wherein, before step S100, further includes the step of establishing a conflict MAC address table in the conflict table module, and the conflict MAC address table is used to store source port information and VLAN information of the conflict MAC address.

In the hash conflict resolution method of the present invention, in step S100, the hash conflict is detected by receiving an interrupt notification of hash conflict from the switch chip.

In the hash conflict resolution method of the present invention, in step S300, ACL rules are configured according to the conflicting MAC address table, and the unicast wire-speed forwarding of messages is realized by sending redirection ACL rules to each port.

In the method for resolving hash conflicts of the present invention, step S200 further includes storing the MAC addresses for which hash conflicts have not been detected in the MAC address table of the MAC address module;

Step S300 also includes, when receiving a message with the MAC address in the MAC address table as the destination address, performing unicast wire-speed forwarding on the message according to the MAC address table.

A hash conflict resolution device for implementing the hash conflict resolution method of the present invention, comprising a control module, a conflict detection module for MAC address hash conflict detection, a conflict table module for creating and maintaining a conflict MAC address table, and a conflict table module for sending and receiving Message transceiver module;

The control module transmits the MAC address learned in the MAC address learning process to the hash conflict detection module to detect the MAC address hash conflict; and transmits the MAC address of the hash conflict detection module to report the hash conflict Stored in the conflict table module; and control the transceiver module to forward the message with the conflict MAC as the destination address at a unicast wire speed according to the conflict MAC address table.

In the hash conflict resolution device of the present invention, wherein the hash conflict detection module further includes an interrupt response unit, the interrupt response unit is used to receive and identify the interrupt notification of the occurrence of a hash conflict sent by the switch chip, and the conflict detection After receiving the interrupt notification, the module reports the hash collision to the control module.

In the hash conflict resolution device of the present invention, the control module further includes a forwarding control unit, the forwarding control unit configures the ACL rule of the transceiver module according to the conflicting MAC address table, and the transceiver module configures the ACL rule according to the ACL Rules for unicast forwarding packets.

The hash conflict resolution device of the present invention, wherein the hash conflict resolution device further includes an address table module, and the MAC address table maintained by it is used to store MAC addresses that have not detected hash conflicts;

The control module controls the transceiver module to perform unicast wire-speed forwarding of the message according to the MAC address table when receiving the message whose destination address is the MAC address in the MAC address table.

The switching device of the present invention has the hash conflict resolution device of the present invention.

It can be seen from the above-mentioned technical scheme that the present invention has the following beneficial effects: the present invention detects and saves the MAC address of the hash conflict, and realizes the unicast wire-speed forwarding of the message whose destination address is the conflicting MAC address, without switching Additional support for chip hardware. The invention also improves the utilization rate of the port bandwidth, and avoids the effective bandwidth of the network being occupied by the unknown unicast flow caused by the hash collision MAC address learning failure.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

FIG. 1 is a flow chart of MAC address learning and message forwarding in the prior art;

Fig. 2 is the flowchart of the MAC address hash conflict resolution method of the embodiment of the present invention;

Fig. 3 is the flowchart of message forwarding in the MAC address hash conflict resolution method of the embodiment of the present invention;

FIG. 4 is a block diagram of a device for resolving MAC address hash conflicts according to the first embodiment of the present invention;

FIG. 5 is a block diagram of a device for resolving MAC address hash conflicts according to the second embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The invention can detect MAC address hash conflicts, and establish a conflicting MAC address table in a conflicting table module other than the address table module to store the conflicting MAC addresses, and simultaneously can perform unicast line-speed forwarding on messages whose DA is a conflicting MAC.

The hash conflict resolution method of the present invention comprises the following steps:

Step S100: performing MAC address hash collision detection on the learned MAC address during the MAC address learning process;

Step S200: When a hash conflict is detected, save the conflicting MAC address in which the hash conflict occurs in a conflicting MAC address table in a conflict table module other than the address table module;

Step S300: When receiving a message with the conflicting MAC address as the destination address, perform unicast wire-speed forwarding on the message according to the conflicting MAC address table.

In the prior art, MAC address learning is usually done by hardware without software participation. Therefore, when a hash collision occurs, special processing cannot be performed on the MAC address of the hash collision. The hash conflict resolution method of the present invention detects the MAC address hash conflict for the learned MAC address during the learning process of the MAC address, and the hash conflict can be detected by the hash conflict resolution method of the present invention, specifically through Two methods of the following two embodiments are realized:

The hash conflict resolution method of the first embodiment of the present invention uses software to learn MAC addresses, and detects hash conflicts of MAC addresses during the process of adding the learned MAC addresses to the MAC address table. For example, call the switch chip to check whether the MAC address table storage is full, to detect the hash collision. If a learned MAC address is added to a certain hash bucket of the address table, and the return value of the function indicates that the hash bucket is full, it means that the MAC address is a conflicting MAC address, so that the CPU is in the hash bucket. When a hash conflict occurs, the hash conflict can be detected in time, and a conflict MAC address table is established to store the conflict MAC address.

In the hash conflict resolution method of the present invention, in the process of MAC address learning, the MAC addresses that do not detect hash conflicts are stored in the MAC address table of the MAC address module; when receiving the MAC address in the MAC address table as the destination address When receiving packets, the packets are forwarded at unicast wire speed according to the MAC address table. When a conflicting MAC address with a hash conflict is detected, the conflicting MAC address is stored in the conflicting MAC address table in the conflicting table module other than the MAC address table module, and the conflicting MAC address table simulates the MAC address table; When forwarding, query the MAC address table and the conflicting MAC address table to forward the message. The conflicting MAC address table does not occupy resources of the MAC address table. The table length of the conflicting MAC address table may be determined according to actual conditions. The hash conflict resolution method of the first embodiment of the present invention further includes the step of creating a conflict MAC address table in the conflict table module before step S100. To ensure that there is enough and stable space to ensure the storage of conflicting MAC addresses.

In the hash conflict resolution method according to the second embodiment of the present invention, in step S100, the hash conflict is detected by receiving an interrupt notification of hash conflict from the switch chip. During the address learning process of the switch chip, when a hash conflict occurs, the switch chip generates an interrupt indicating that a hash conflict has occurred through the interrupt service program, and performs the process by receiving and identifying the interrupt indicating that a hash conflict has occurred. Detection of hash collisions. The hash conflict resolution method of the second embodiment of the present invention requires the switch chip to generate an interrupt when a hash conflict occurs, and it needs to rely on the switch chip to send a notification through an interrupt when a hash conflict occurs.

After a hash collision is detected, the MAC address of the hash collision is stored in the established conflict MAC address table. When a hash collision is detected, use the MAC address table in the form of Table 3 to save the MAC address of the hash collision. In this table, at least source port information and VLAN information of packets whose SA is a conflicting MAC address need to be recorded as a basis for forwarding. In the conflicting MAC address table, other forwarding attributes about the MAC address or maintenance information about the MAC address may also be stored. The conflicting MAC address table and the MAC address table can have the same structure, and they can be stored in the order of MAC addresses, or in the order in which the conflicting MAC addresses are added.

The hash conflict resolution method of the embodiment of the present invention, as described in Table 3, implements unicast wire-speed forwarding of messages whose destination addresses are conflict MAC addresses according to the hash conflict MAC address information stored in the conflict MAC address table. In the hash conflict resolution method of the present invention, its conflict table module is actually a hardware module, such as an ACL module. When it is an ACL module, it realizes that the destination MAC address is a conflict MAC Addressed packets are forwarded at unicast wire speed.

In the hash conflict resolution method of the embodiment of the present invention, the above-mentioned unicast wire-speed forwarding is realized by issuing redirection ACL (Access Control list, access control list) rules. Specifically, configure the ACL rules of the switching chip according to the conflicting MAC address table, and issue the ACL rules to all ports except the source port. The detected packets are directly forwarded to the port corresponding to the table entry at wire speed, realizing unicast wire speed forwarding of the packets. The hash conflict resolution method of the present invention can also use other methods to realize the unicast wire-speed forwarding of the message whose destination address is the conflicting MAC address.

For the redirection ACL rule, the ACL module can decide how to process the packet according to the characteristics of the packet. It belongs to the same hardware resource as the MAC address table, but it belongs to different hardware modules.

When forwarding packets with conflicting MAC as DA, you can add redirection ACL rules, and forward packets whose combination of destination MAC and VLAN ID can be found in the HASH conflict table to the specified port.

table 3

MAC address VLAN ID The port number 00:e0:fc:00:00:01 1 14 00:e0:fc:00:00:02 2 15 00:e0:fc:00:00:03 3 16

Take the first entry in Table 3 as an example. For this HASH conflict entry, an ACL rule will be issued: forward all packets with DA=00:e0:fc:00:00:01 and VLAN ID=1 to port 14.

After a message enters a switching device such as a switch, it will be processed by multiple hardware modules. Generally speaking, it will enter the module of the MAC address table first, and then enter the ACL module. In this way, for a message with a common MAC (no HASH conflict) as DA, you can find the corresponding entry in the MAC address table, and forward it according to the port information in the entry in the MAC address table; for a message with a HASH conflict MAC as DA text, it will fail to search in the MAC address table, and then continue to enter the ACL module, find the matching ACL rule (redirection ACL), and forward it to the specified port according to the rule. The forwarding performance is the same as that of the MAC module, which is hardware forwarding.

To sum up, using the above solution, hardware line-speed forwarding can be realized for messages with all types (conflicting and non-conflicting) MAC addresses as DAs.

As shown in Figure 2, the hash collision detection method of the present invention can refine step S100 into steps S100-S140, step S200 includes step S210 and step S220 executed respectively, step S300 includes step S310 and step S320, to obtain from Port 1 receives a message whose SA is MAC-A as an example, and the hash conflict resolution methods of the first embodiment and the second embodiment of the present invention all include the following steps in sequence:

Step S110: receiving a message from port 1;

Step S120: Parsing out the source address MAC-A of the message;

Step S130: learning the MAC address;

Step S140: Perform MAC address hash conflict detection on the learned MAC address; if the MAC address has a hash conflict, proceed to step S210; if no hash conflict occurs, proceed to step S220;

Step S210: Add MAC-A to the conflicting MAC address table; go to step S310;

Step S220: Add MAC-A to the MAC address table; go to step S320;

Step S310: Configure and issue a redirection ACL rule to redirect the packet whose destination address is MAC-A to port 1; go to step S320;

Step S320: The message whose destination address is MAC-A is forwarded to port 1 in unicast mode; the process of forwarding the message through MAC address learning ends;

As shown in Figure 3, step S320 can be further refined into steps S321-S327, that is, the process of message forwarding in the MAC address hash conflict resolution method of the embodiment of the present invention includes the following steps:

Step S321: receiving the message to be forwarded;

Step S322: Extracting the destination address and VLAN ID of the message to be forwarded;

Step S323: Match the MAC address table. Promptly search the MAC address table to have the table item of this destination address and VLAN ID both combination; If match successfully, execute step S324; If match unsuccessfully, execute step S325;

Step S324: Unicast forwarding the message according to the MAC address table; the message forwarding process ends;

Step S325: enter the ACL module;

Step S326: Find the ACL rule corresponding to the destination address;

Step S327: According to the found ACL rule, forward the packet to the port specified in the rule in unicast wire-speed; the packet forwarding process ends.

It can be seen from the above process that the hash conflict resolution method of the present invention will not cause the message with the conflicting MAC address as the destination MAC address to be broadcast in the VLAN, and will not occupy the effective bandwidth of other ports. It greatly reduces the intra-VLAN broadcast caused by a large number of unknown unicast packets in the network, and avoids the waste of network bandwidth.

The hash conflict resolution device of the present invention that implements the hash conflict resolution method of the present invention includes a control module, a conflict detection module for MAC address hash conflict detection, a conflict table module for creating and maintaining a conflict MAC address table, and a conflict table module for sending and receiving Message transceiver module;

The control module transmits the MAC address learned in the MAC address learning process to the hash conflict detection module to detect the MAC address hash conflict; and transmits the MAC address of the hash conflict detection module to report the hash conflict Stored in the conflict table module; and control the transceiver module to forward the message with the conflict MAC as the destination address at a unicast wire speed according to the conflict MAC address table.

As shown in Figure 4, the hash conflict resolution device of the first embodiment of the present invention includes a control module, a conflict detection module, a conflict table module and an address table module for creating and maintaining a MAC address table;

The control module transmits the MAC address learned in the MAC address learning process to the hash conflict detection module to detect the MAC address hash conflict; and transmits the MAC address of the hash conflict detection module to report the hash conflict Stored in the conflict table module; and control the transceiver module to forward the message with the conflict MAC as the destination address at a unicast wire speed according to the conflict MAC address table.

The control module includes a storage control unit and a forwarding control unit.

The storage control module, in the process of learning the MAC address, transmits the unlearned MAC address sent by the transceiver module to the hash conflict detection module for detection, and controls the address table module so that no hash will occur. The conflicting MAC address is stored in the MAC address table; the conflict table module is controlled to store the conflicting MAC address in the MAC address table;

The forwarding control unit controls the forwarding module, and forwards the message at a unicast wire speed according to the MAC address table and the conflicting address table;

The hash detection module realizes the detection of MAC address hash conflicts, and receives the feedback from the address table module. For example, when a certain hash bucket is full and can no longer store a new MAC address, it returns to the hash detection module. For the information that the hash bucket is full, the hash detection module reports the occurrence of a hash collision to the control module, thereby realizing the detection of the hash collision. When a hash conflict occurs, the storage control unit controls the conflict table module, and stores the MAC address where the hash conflict occurs in the conflict MAC address table of the conflict table module.

The conflicting MAC address table at least needs to store source port information and VLAN information of packets whose source addresses are conflicting MAC addresses. In the conflict address table, other forwarding attributes about the MAC address or maintenance information about the MAC address may also be saved.

The device for resolving hash conflicts also includes an address table module, and the MAC address table maintained by it is used to save MAC addresses that do not detect hash conflicts; When the MAC address is the destination address of the packet, the packet is forwarded at a unicast wire speed according to the MAC address table.

The transceiver module: includes a receiving unit and a forwarding unit; the receiving unit receives the MAC address learned by the switching chip and inputs it to the control module; the forwarding unit receives the control instructions of the forwarding control module, Packets whose addresses are in the MAC address table are forwarded at a unicast wire speed according to the conflicting MAC address table, and packets whose destination addresses are conflicting MAC addresses are forwarded at a unicast wire speed according to the conflicting MAC address table. The forwarding control unit configures the ACL rules of the transceiver module according to the conflicting MAC address table in the conflict table module, and the transceiver module unicasts and forwards messages according to the ACL rules. The forwarding control unit issues a redirection ACL rule to the forwarding unit, and the forwarding unit performs unicast wire-speed forwarding on packets whose destination address is a conflicting MAC address according to the ACL rule.

The hash conflict resolution device of the second embodiment of the present invention, as shown in Figure 5, its control module, transceiver module, address table module, conflict table module is the same as the hash conflict resolution device of the first embodiment, the difference is , the hash conflict detection module also includes an interrupt response unit, the interrupt response unit is used to receive and identify the interrupt notification that the hash conflict is sent by the switch chip, after the conflict detection module receives the interrupt notification, it sends The control module reports that a hash collision occurred.

The hash conflict detection device of the present invention can be applied to switching equipment that forwards messages through MAC address learning.

The switching device of the present invention has the hash collision detection device of the present invention. The switching device of the present invention can be a switch, a router or other switching devices.

The above are only preferred feasible embodiments of the present invention, and the embodiments are not intended to limit the scope of patent protection of the present invention, so all equivalent structural changes made by using the description and accompanying drawings of the present invention are equally valid. Should be included in the protection scope of the present invention.

Claims (10)

1. A hash conflict resolution method, comprising the following steps: Step S100: performing MAC address hash collision detection on the learned MAC address during the MAC address learning process; Step S200: When a hash conflict is detected, save the conflicting MAC address in which the hash conflict occurs in a conflicting MAC address table in a conflict table module other than the address table module; Step S300: When receiving a message with the conflicting MAC address as the destination address, perform unicast wire-speed forwarding on the message according to the conflicting MAC address table. 2. the hash conflict resolution method as claimed in claim 1, is characterized in that, before step S100, also comprises the step of setting up conflict MAC address table in conflict table module, conflict MAC address table is used to preserve the conflict MAC address Source port information and VLAN information. 3. The hash conflict resolution method according to claim 1, characterized in that, in step S100, the hash conflict is detected by receiving an interrupt notification that a hash conflict occurs from a switch chip. 4. The hash conflict resolution method according to claim 1, 2 or 3, characterized in that: in step S300, configure ACL rules according to the conflicting MAC address table, and issue redirection ACL rules to each port In this way, the unicast wire-speed forwarding of packets is realized. 5. The method for resolving hash conflicts as claimed in claim 1, wherein step S200 also includes that the MAC addresses that do not detect hash conflicts are stored in the MAC address table of the MAC address module; Step S300 also includes, when receiving a message with the MAC address in the MAC address table as the destination address, performing unicast wire-speed forwarding on the message according to the MAC address table. 6. A hash conflict resolution device realizing the hash conflict resolution method of claim 1, wherein the hash conflict resolution device comprises a control module, a conflict detection module for MAC address hash conflict detection , Create and maintain the conflict table module of the conflict MAC address table and the transceiver module for sending and receiving messages; The control module transmits the MAC address learned in the MAC address learning process to the hash conflict detection module to detect the MAC address hash conflict; and transmits the MAC address of the hash conflict detection module to report the hash conflict Stored in the conflict table module; and control the transceiver module to forward the message with the conflict MAC as the destination address at a unicast wire speed according to the conflict MAC address table. 7. The hash conflict resolution device according to claim 6, characterized in that: the hash conflict detection module also includes an interrupt response unit, the interrupt response unit is used to receive and identify the occurrence of a hash conflict sent by the switch chip After receiving the interruption notification, the conflict detection module reports the hash collision to the control module. 8. The device for resolving hash conflicts according to claim 6 or 7, wherein the control module further comprises a forwarding control unit, and the forwarding control unit configures the ACL of the transceiver module according to the conflicting MAC address table rules, the transceiver module unicast forwards packets according to the ACL rules. 9. The device for resolving hash conflicts as claimed in claim 6, characterized in that: the device for resolving hash conflicts also includes an address table module, and the MAC address table maintained by it is used to save the MAC addresses that do not detect hash conflicts ; The control module controls the transceiver module to perform unicast wire-speed forwarding of the message according to the MAC address table when receiving the message whose destination address is the MAC address in the MAC address table. 10. A switching device, characterized in that it has the hash conflict resolution device according to claim 6 or 7.

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