CN102158395A - Device and method for processing neighbor discovery items of router - Google Patents

Abstract

The invention relates to a device for processing router neighbor discovery entries. The device includes a microcode forwarding module, which is used to count the use of the ND entry when the neighbor discovery entry is used for message forwarding; a forwarding table management module is used for Provide the count of the ND entry to the ND protocol module; the ND protocol module is used to read and accumulate the count of the ND entry of each line card through the forwarding table management module when the ND entry has just become stale, and when the ND entry is After a certain period of time in the stale state, read the counts of the ND entries of each line card again and accumulate them, and compare the accumulated results of the ND entries read twice before and after. If the accumulated results of the ND entries read twice before and after are consistent, the The ND entry is aged and deleted. In addition, the invention also provides a method for processing router neighbor discovery entries. Through the technical scheme of the invention, the normal aging of the ND entry is guaranteed, and the phenomenon of packet loss is prevented.

Description

Device and method for router neighbor discovery entry processing

technical field

The invention relates to the field of data communication, in particular to a device and method for processing router neighbor discovery entries.

Background technique

With the increasing depletion of IPv4 addresses, a large number of IPv6 network deployments are gradually put on the agenda. In the IPv6 protocol, ND (Neighbor Discovery, Neighbor Discovery) protocol is a brand new protocol, which implements IPv4 ARP (Address Resolution Protocol) , ICMP (Control Message Protocol), all the functions of the router discovery part and the redirection part, and has a neighbor unreachable detection mechanism. When an IPv6 node appears on the network, other IPv6 nodes on the directly connected link can discover it through the ND protocol, and then obtain its link layer address. The relationship table between IPv6 addresses and link-layer addresses in an IPv6 node is called a neighbor entry, or ND entry for short. Generally, it has three basic fields: IPv6 next-hop address, outgoing interface, and link-layer MAC address (network hardware address). There are also information such as the state of the ND entry, the switching time of the neighbor state of the ND entry, and the like.

According to RFC2461, ND entries have five states, which are incomplete (incomplete), reachable (reachable), stale (stale), delay (delayed), and probe (detection). As shown in FIG. 1 , it is a schematic diagram of state transition of an ND entry. When a node wants to perform address resolution, it will actively create an ND entry whose state is incomplete, and send an NS (Neighbor Solicitation) message, and if it receives a response NA (Neighbor Advertisement) message, it means that the neighbor is reachable , the state becomes reachable; if no response message is received, it means that the neighbor is unreachable, and the created entry is deleted. After receiving the last reachability acknowledgment NA message, after the "reachable time", the default is about 30 seconds, the entry status becomes stale. In the stale state, if you use this entry to send a message, its state will change to delay, the delay state lasts for a period of time, the default is 5 seconds, it becomes probe, and an NS message for reachability detection is sent, if a response message is received , the state becomes reachable again; otherwise, delete the entry. For an entry in the stale state, if there is no message sent for a period of time (the default is 24 hours), the entry will be aged and deleted.

On routers, the control plane and the forwarding plane are generally separated. The function of the forwarding plane is mainly realized by microcode, which is responsible for forwarding packets. The control plane is mainly realized by the IPv6 protocol stack module, and the forwarding plane is generated by means of static configuration and dynamic learning. The required forwarding resources are sent to the forwarding table management module for the microcode to forward messages. The IPv6 protocol stack module is responsible for the learning of ND entries, and sends the learning to the forwarding table management module for the microcode to forward messages. As shown in FIG. 2 , it is a schematic diagram of message sending after an ND entry is aged. According to the regulations of RFC2461, the ND state transition needs to be triggered by a message, and most of the data messages on the router are forwarded by microcode, and will not be sent to the IPv6 protocol stack module, so the ND entry in the stale state is changed because there is no message to trigger it state, it will last for 24 hours, and then aged and deleted. This aging ND entry, if the microcode has been using it to forward messages, will cause a large number of NO ND messages when it is deleted (when the microcode forwards messages, the ND entry cannot be found when forwarding , which is called NO ND message) is sent to the control plane, causing a high CPU utilization rate on the control plane, especially in the case of a large number of ND entries, which will cause ND entries to be re-learned and delivered for a long time, resulting in forwarding flow packet loss. This phenomenon will appear again and again, by default, once every 24 hours or so, and the routing protocol may be disconnected due to busy CPU, causing more serious consequences.

At present, there is no clear solution in IPv6 for this, and it is generally done with reference to the ARP module of IPv4. ARP usually has the following methods: 1. Convert dynamic ARP to static ARP; 2. Relearn ARP before the ARP aging time expires. Specifically for IPv6, it is to convert dynamic ND entries into static ND entries, or relearn before the ND aging time expires. These two methods have obvious limitations, which will cause some unused ND entries to exist for a long time, occupying limited ND table resources, and seriously causing a large number of subsequent packet loss due to the lack of ND entries for newly added forwarding traffic.

Contents of the invention

The technical problem solved by the invention is to provide a router neighbor discovery entry processing device, which ensures normal aging of ND entries and prevents packet loss. In addition, the invention also provides a method for processing router neighbor discovery entries.

A device for processing router neighbor discovery entries provided by the present invention includes:

The microcode forwarding module is used to count the use of the ND entry when the neighbor discovery entry is used for message forwarding;

The forwarding table management module is used to provide the count of ND entries to the ND protocol module;

The ND protocol module is used to read and accumulate the counts of the ND entries of each line card through the forwarding table management module when the ND entry just becomes obsolete, and to read each count again after the ND entry is obsolete for a specific time. The ND entry of the line card is counted and accumulated, and the accumulated results of the ND entries read twice before and after are compared. If the accumulated results of the ND entries read twice before and after are consistent, the ND entry is aged and deleted.

Preferably, the ND protocol module is further configured to change the state of the ND entry into a delayed state and perform reachability detection when the accumulative results of the two read ND entries are inconsistent, and if the detection result is reachable , then change the state of the ND entry and re-send it to the forwarding table management module for use by the microcode, otherwise delete the ND entry.

Preferably, said counting the use of ND entries is,

Each time a packet is forwarded using this ND entry, the usage count is added up once.

Preferably, after the count of the ND entry of each line card is read by the forwarding table management module and accumulated,

Save the accumulated result in the ND entry.

Preferably, the specific time is any period before aging deletion.

The present invention also provides a method for processing router ND entries, the method comprising:

When the microcode forwarding module uses the ND entry to forward the message, the use of the ND entry is counted;

When the ND entry state becomes stale, the ND protocol module reads and accumulates the usage count corresponding to the ND entry of each line card through the forwarding table management module;

After the ND protocol module is in the stale state for a specific time, it reads and accumulates the usage count corresponding to the ND entry of each line card through the forwarding table management module again;

Determine whether the accumulated results of the two usage counts are consistent, and if they are consistent, age and delete the ND entry.

Preferably, the method also includes,

When the accumulative results of the two usage counts are inconsistent, the state of the ND entry is changed to the delay state, and the reachability detection is performed. If the detection result is reachable, the state of the ND entry is changed and sent to the forwarding table management module again. For use by microcode, otherwise remove said ND entry.

Preferably, said counting the use of the ND entry is,

Each time the ND entry is used to forward a packet, the usage count is incremented once.

Preferably, after reading and accumulating the use counts corresponding to the ND entries of each line card through the forwarding table management module,

Save the accumulated result in the ND entry.

Preferably, the specific time is any period before aging deletion.

Compared with the prior art, the technical solution of the present invention ensures the normal aging of ND entries, effectively avoids a large amount of packet loss of forwarding traffic due to the aging of ND entries due to the lack of ND entries, and ensures the normal operation of the router.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Figure 1 is a schematic diagram of state transitions of ND entries;

Figure 2 is a schematic diagram of message sending after ND entry aging;

Fig. 3 is a structural diagram of Embodiment 1 of the present invention;

FIG. 4 is a flow chart of Embodiment 2 of the present invention.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in FIG. 3 , it is a structural diagram of Embodiment 1 of the present invention, and a device for forwarding router messages is provided. The device includes an ND protocol module, a forwarding table management module, and a microcode forwarding module, wherein,

The microcode forwarding module, when using an ND entry for message forwarding, counts the use of the ND entry, and each time a message is forwarded using the ND entry, the usage count is accumulated once; it should be noted that the count here is accumulated once It is not limited to using the ND entry to forward one message each time, and it can also be in other forms, use the ND entry to forward two or more messages, and use the count to accumulate once;

The forwarding table management module is used to provide the count of ND entries to the ND protocol module;

Its specific form is to provide a read channel for the usage count of ND entries for the ND protocol module to read the count;

The ND protocol module, when the ND entry just becomes the stale state, reads and accumulates the use count of the ND entry of each line card through the forwarding table management module, and saves the accumulated result in the ND entry. The user interface displays; after the ND entry is in the stale state for a specific period of time, 24 hours by default, before aging and deleting, the usage count of the ND entry of each line card is read again and accumulated; the ND usage count read twice before and after Comparing the cumulative results, if the two are consistent, it indicates that the ND entry has not been used during this period of time, and can be aged and deleted (ignoring the small probability of usage count reversal); if not, it indicates that during this period, The ND entry is still in use. At this time, the state of the ND entry can be changed to the delay state, and then reachability detection is performed. If the detection result is still reachable, the new MAC information is written to the microcode through the forwarding table management module; Otherwise delete the entry.

As shown in FIG. 4, it is a flow chart of Embodiment 2 of the present invention, which provides a method for router message forwarding. The method includes:

The implementation method includes the following steps:

S401, when the microcode forwarding module uses the ND entry to forward the message, count the use of the ND entry;

It should be noted that the accumulation of the count here is not limited to using the ND entry to forward one packet each time, and it can also be in other forms, using the ND entry to forward two or more packets, and using the count to accumulate once;

S402, when the state of the ND entry becomes stale, the ND protocol module reads and accumulates the usage count corresponding to the ND entry of each line card through the forwarding table management module, and the accumulated result is stored in the ND entry, and this result can also be stored in the user interface display;

S403, the ND protocol module reads and accumulates the usage count corresponding to the ND entry of each line card through the forwarding table management module again before the stale state is aged out and deleted;

S404 judges whether the two use count accumulation results are consistent, if the two are consistent, it can be considered that there is no message to use this ND entry to forward during the period of time entering the stale state, and can be deleted; For a period of time, there are messages forwarded using this ND entry. This entry cannot be deleted. Re-perform the reachability detection, update the ND status, and re-send it to the forwarding table management module for use by the microcode.

The above description shows and describes a preferred embodiment of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various Various other combinations, modifications, and environments can be made within the scope of the inventive concept described herein, by the above teachings or by skill or knowledge in the relevant field. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (10)

1. A device for router neighbor discovery entry processing, characterized in that the device comprises, The microcode forwarding module is used for counting the use of the neighbor discovery entry when the neighbor discovery entry is used for message forwarding; The forwarding table management module is used to provide the neighbor discovery protocol module with the count of neighbor discovery entries; The neighbor discovery protocol module is used to read and accumulate the counts of the neighbor discovery entries of each line card through the forwarding table management module when the neighbor discovery entry has just become stale, and after the neighbor discovery entry is stale for a certain period of time, Read the counts of the neighbor discovery entries of each line card again and accumulate them, and compare the accumulated results of the neighbor discovery entries read twice before and after. If the accumulated results of the neighbor discovery entries read twice before and after are consistent, the neighbor discovery Entries are aged and deleted. 2. The device according to claim 1, characterized in that, The neighbor discovery protocol module is further configured to change the state of the neighbor discovery entry into a delayed state when the accumulative results of the neighbor discovery entries read twice before and after are inconsistent, and perform reachability detection, if the detection result is reachable , then change the state of the neighbor discovery entry and resend it to the forwarding table management module for use by the microcode; otherwise, delete the neighbor discovery entry. 3. The device according to claim 1 or 2, wherein the counting the use of neighbor discovery entries is: Each time a packet is forwarded using this neighbor discovery entry, the usage count is incremented once. 4. The device according to claim 1 or 2, characterized in that, after the counting of the neighbor discovery entries of each line card is read and accumulated by the forwarding table management module, Save the accumulated result in a neighbor discovery entry. 5. The device according to claim 1 or 2, characterized in that, The specific time is any period before aging deletion. 6. A method for router neighbor discovery entry processing, characterized in that the method comprises, When the microcode forwarding module uses the neighbor discovery entry to forward the message, it counts the use of the neighbor discovery entry; The neighbor discovery protocol module reads and accumulates the usage count corresponding to the neighbor discovery entry of each line card through the forwarding table management module when the state of the neighbor discovery entry becomes stale; The neighbor discovery protocol module reads the usage count corresponding to the neighbor discovery entry of each line card through the forwarding table management module again after the stale state is a specific time, and accumulates it; Determine whether the accumulated results of the two usage counts are consistent, and if they are consistent, the neighbor discovery entry is aged and deleted. 7. The method of claim 6, further comprising, When the accumulative results of the usage counts in the previous two times are inconsistent, the state of the neighbor discovery entry is changed to a delayed state, and a reachability detection is performed. If the detection result is reachable, the state of the neighbor discovery entry is changed and re-delivered to the forwarding table management module for use by microcode, otherwise remove said neighbor discovery entry. 8. The method according to claim 6 or 7, wherein the counting the use of the neighbor discovery entry is: Each time a packet is forwarded using this neighbor discovery entry, the usage count is incremented once. 9. The method according to claim 6 or 7, characterized in that, after the usage count corresponding to the neighbor discovery entry of each line card is read by the forwarding table management module and accumulated, Save the accumulated result in a neighbor discovery entry. 10. The method according to claim 6 or 7, characterized in that, The specific time is any period before aging deletion.

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