Method for quickly updating route in OLSR protocol

Abstract

The invention relates to the field of wireless ad hoc networks, in particular to a method for quickly updating routing in an OLSR protocol. When the node receives the TC message, whether enough routing information is recorded or not is judged according to the record in the repeated set, and if the message is the latest message and more routing numbers can be recorded, judgment is continued; and if the message is received for the first time, the routing set reaching the message originating node is emptied. Recording a route pointing to the message originating address, wherein the next hop address of the route is the source address of the IP packet header to which the message belongs; and the routing set taking the message originating node as the last but one hop is emptied. Then, for each non-MPR node carried in the message, a route pointing to the address of the node is recorded, and the next hop address is the source address of the IP packet header to which the message belongs; according to the method, all routes reaching all nodes in the network do not need to be recalculated every time, a large amount of repeated calculation is avoided, and the updating process is more concise and efficient.

Description

Technical Field

[0001] The invention relates to the field of wireless self-organizing networks, and in particular to a fast routing update method in an OLSR protocol used in wireless self-organizing networks. Background Art

[0002] In the OLSR protocol, whenever the information in the link set, neighbor set, two-hop neighbor set, or topology set changes, the node needs to update the routing table. The node first deletes all entries in the current routing table, and then re-establishes routing table entries to all one-hop neighbors based on the information in the link set and neighbor set. Then, based on the information in the two-hop neighbor set, re-establishes routing table entries to all two-hop neighbors. After these steps are completed, the node searches for the corresponding information in the topology set and the already generated routing table entries, and successively establishes routing table entries to reach more distant nodes until the routing table entries to all other nodes in the network are re-established.

[0003] The main problems with the above methods are:

[0004] 1. Every time the route is updated, the routing table must be cleared first, and then all routes must be recalculated, so the amount of calculation is very large.

[0005] 2. The information changes that trigger route updates sometimes only affect some routes. In this case, recalculating all routes means that many calculations are actually repeated. Summary of the invention

[0006] The current route updating method in the OLSR protocol has a large amount of calculation and many repeated calculations. To address this problem, the present invention designs a route updating method that can independently update routes to different nodes, avoids a large amount of repeated calculations, and can complete route updating more quickly.

[0007] The technical solution adopted by the present invention is:

[0008] A method for quickly updating routing in an OLSR protocol includes the following processes:

[0009] Step 1, select the MPR node according to the MPR selection method, and the MPR node periodically generates a TC message, which contains the symmetric one-hop neighbors that are not MPRs; and define the node's routing table and repeat set, each entry in the routing table includes the destination address R_dest_addr of the route and the route set to the destination address, and the routing set records multiple routes, each route includes the next hop address R_next_addr, the last address before reaching the destination address R_last_addr, the number of hops R_dist, the effective time R_time and the priority R_priority; the repeat set includes the number of records D_rec_num, the originating address Originator Address of the message and the message sequence number Message Sequence Number;

[0010] Step 2: When a node receives a TC message, it immediately forwards the message if it can be forwarded according to the current rules, and checks whether the TC message meets any of the following conditions. If it does, it does not participate in the routing update. If it does not, it is recorded in the duplicate set, and the number of records D_rec_num is increased by 1, and then step 3 is executed;

[0011] 1) The combination of the message's Originator Address and Message Sequence Number has been recorded in the duplicate set, and the number of records of the same value of this combination exceeds the predefined threshold;

[0012] 2) The Message Sequence Number of the message is smaller than the largest Message Sequence Number of all messages with the same OriginatorAddress recorded in the duplicate set;

[0013] Step 3: Process the originator address in the message:

[0014] If this is the first time this TC message is received, all routes with the Originator Address as the destination address in the current routing table are deleted;

[0015] Add a route with Originator Address as the destination address. If this is the first time this TC message is received, the priority is set to the highest level. After the first time this TC message is received, the priority is lowered in turn.

[0016] Step 4: Process the existing route with Originator Address as R_last_addr:

[0017] If the number of records D_rec_num in the duplicate set is 1, the routes with Originator Address as R_last_addr in the route set of each routing table entry are deleted, and the R_priority of each route is adjusted according to the R_dist of the remaining routes in the set. The smaller the hop count, the higher the priority.

[0018] Step 5: Process each Advertised Neighbor Main Address in the message:

[0019] Add a route with the Advertised Neighbor Main Address as the destination address, record the hop count of this route as the hop count in the message plus 1, and adjust the priority of multiple routes with the same destination address. The smaller the hop count, the higher the priority.

[0020] Furthermore, the following process is also included:

[0021] Step 6: When a node finds a new symmetric one-hop neighbor, it updates the route according to the following rules:

[0022] Add a route with the address of the new symmetric one-hop neighbor as the destination address, set the priority to the highest level, and reduce the priority of other existing routes with the address of the new symmetric one-hop neighbor as the destination address by one level.

[0023] Furthermore, the following process is also included:

[0024] Step 7: When a node finds that its symmetric one-hop neighbor becomes asymmetric, it updates the route according to the following rules:

[0025] For each routing table entry, check each route in the routing set of the routing table entry. If R_next_addr is this one-hop neighbor, delete the corresponding route; if the routing set of the table entry is not empty at the end, reorder the routes in the set based on the current priority to obtain a new priority; otherwise, delete the corresponding routing table entry.

[0026] Furthermore, the specific process of step 3 is as follows:

[0027] If there is no entry in the routing table with R_dest_addr equal to Originator Address, a new routing entry is added, R_dest_addr in the routing entry is set to Originator Address, and a new route is added, R_next_addr in the route is set to the node address of the forwarding message, that is, the source address in the IP header, R_last_addr is empty, R_dist is set to the hop count in the message, R_time is set to the current time plus the topology hold time TOP_HOLD_TIME, and R_priority is set to the highest priority;

[0028] Otherwise, the entry with R_dest_addr equal to Originator Address is processed as follows:

[0029] If the number of records in the duplicate set D_rec_num is 1, clear the routing set of the corresponding table entry;

[0030] Add a new route to the route collection. In the route, R_next_addr is set to the node address of the forwarding message, R_last_addr is empty, R_dist is set to the Hop Count in the message, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is equal to the lowest priority in the route collection and one level lower.

[0031] Furthermore, the specific process of step 5 is as follows:

[0032] First check whether the neighbor corresponding to the Advertised Neighbor Main Address is a one-hop neighbor. If it is, no processing is performed. Otherwise, the following processing is performed:

[0033] If there is no entry in the routing table with R_dest_addr equal to Advertised Neighbor Main Address, a new routing entry is added, R_dest_addr in the routing entry is set to Advertised Neighbor Main Address, and a new route is added to the routing set, R_next_addr in the route is set to the node address of the forwarding message, R_last_addr is set to the Originator Address of the message, R_dist is set to the Hop Count in the message plus 1, R_time is equal to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority;

[0034] Otherwise, for the entry whose R_dest_addr is equal to the Advertised Neighbor Main Address, add a new route to the route collection, set R_next_addr in the route to the node address of the forwarding message, set R_last_addr to the Originator Address of the message, set R_dist to the Hop Count in the message plus 1, and set R_time to the current time plus TOP_HOLD_TIME; then adjust the R_priority of each route in the route collection according to R_dist, and the smaller the hop count, the higher the priority.

[0035] Furthermore, the specific process of step 6 is as follows:

[0036] If there is no entry in the routing table with R_dest_addr equal to the address of the new symmetric one-hop neighbor, then a new routing entry is added, and R_dest_addr in the routing entry is set to the address of the new symmetric one-hop neighbor. A new route is added to the routing set, and R_next_addr in the route is set to the address of the new symmetric one-hop neighbor, R_last_addr is empty, R_dist is set to 1, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority.

[0037] Otherwise, for the entry whose R_dest_addr is equal to the address of the new symmetric one-hop neighbor, a new route is added to the route set, R_next_addr in the route is set to the address of the new symmetric one-hop neighbor, R_last_addr is empty, R_dist is set to 1, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority; for other routes in the route set, R_priority is reduced by one level compared to the current value.

[0038] The advantages of the present invention compared with the prior art are:

[0039] Each time the OLSR protocol updates the route, it first clears the current routing table, and then recalculates the routes to all other nodes in the network based on neighbor information and topology information. Compared with the existing route update method, the present invention does not need to recalculate all routes to all nodes in the network every time, but independently updates the routes to the corresponding nodes based on TC messages, avoiding a large number of repeated calculations, and the update process is more concise and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 In the embodiment of the present invention, node 4 updates the routing map based on the TC message of node 1.

[0041] Figure 2 In the embodiment of the present invention, node 4 updates the routing map based on the TC message of node 6.

[0042] Figure 3 In the embodiment of the present invention, node 4 updates the routing map based on the TC message of node 3. DETAILED DESCRIPTION

[0043] The present invention will be further explained below in conjunction with the accompanying drawings.

[0044] In the OLSR protocol, each MPR node periodically generates and sends TC messages, and forwards TC messages received from its own MPRselector. The TC message originating from node A may reach node B successively through different paths. Therefore, the different paths through which the message received by node B passes can be considered as different routes from node B to node A. Based on this idea, when the TC message originating from node A reaches all other nodes in the network, the routes from these nodes to node A can be established or updated. At the same time, other routes in the routing table do not need to be updated.

[0045] In a smaller network, non-MPR nodes can also generate and send TC messages. In this way, all nodes can obtain the route to the node where the message originated based on the received TC message. If the network is large, in order to reduce the number of TC messages, only MPR nodes can generate and send TC messages. This means that the route to non-MPR nodes cannot be directly obtained according to the above ideas. At this time, although the non-MPR node cannot send TC messages, it will appear in the TC message originated from the MPR node selected by it. Therefore, when node B receives a TC message originating from node A, in addition to establishing or updating the route to node A, it can also establish or update the route to the MPR selector node of node A that is not an MPR. Based on the above ideas, the following route update method can be obtained.

[0046] A method for quickly updating routing in an OLSR protocol specifically includes the following processes:

[0047] Step 1: Select the MPR node according to the MPR selection method. The MPR node periodically generates a TC message, which contains the symmetric one-hop neighbors that are not MPRs. The node's routing table and repetition set are defined. Each entry in the routing table includes the destination address R_dest_addr of the route and the set of routes to the destination address. The routing set records multiple routes, each of which includes the next hop address R_next_addr, the last address before reaching the destination address R_last_addr, the number of hops R_dist, the effective time R_time and the priority R_priority. The repetition set includes the number of records D_rec_num, the originating address Originator Address of the message and the message sequence number Message Sequence Number.

[0048] Step 2: When a node receives a TC message, it immediately forwards the message if it can be forwarded according to the current rules, and checks whether the TC message meets any of the following conditions. If it does, it does not participate in the routing update. If it does not, it is recorded in the duplicate set, and the number of records D_rec_num is increased by 1, and then step 3 is executed;

[0049] 1) The combination of the message's Originator Address and Message Sequence Number has been recorded in the duplicate set, and the number of records of the same value of this combination exceeds the predefined threshold;

[0050] 2) The Message Sequence Number of the message is less than the largest Message Sequence Number of all messages with the same OriginatorAddress recorded in the duplicate set.

[0051] Step 3: Process the originator address in the message:

[0052] If this is the first time this TC message is received, all routes with the Originator Address as the destination address in the current routing table are deleted;

[0053] Add a route with Originator Address as the destination address. If this is the first time this TC message is received, the priority is set to the highest level; after the first time this TC message is received, the priority is lowered.

[0054] The specific process of step 3 is as follows:

[0055] If there is no entry in the routing table with R_dest_addr equal to Originator Address, a new routing entry is added, R_dest_addr in the routing entry is set to Originator Address, and a new route is added, R_next_addr in the route is set to the node address of the forwarding message, that is, the source address in the IP header, R_last_addr is empty, R_dist is set to the hop count in the message, R_time is set to the current time plus the topology hold time TOP_HOLD_TIME, and R_priority is set to the highest priority;

[0056] Otherwise, the entry with R_dest_addr equal to Originator Address is processed as follows:

[0057] If the number of records in the duplicate set D_rec_num is 1, clear the routing set of the corresponding table entry;

[0058] Add a new route to the route collection. In the route, R_next_addr is set to the node address of the forwarding message, R_last_addr is empty, R_dist is set to the Hop Count in the message, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is equal to the lowest priority in the route collection and one level lower.

[0059] Step 4: Process the existing route with Originator Address as R_last_addr:

[0060] If the number of records D_rec_num in the duplicate set is 1, the routes with Originator Address as R_last_addr in the route set of each routing table entry are deleted, and the R_priority of each route is adjusted according to the R_dist of the remaining routes in the set. The smaller the hop count, the higher the priority.

[0061] Step 5: Process each Advertised Neighbor Main Address in the message:

[0062] Add a route with the Advertised Neighbor Main Address as the destination address, record the hop count of this route as the hop count in the message plus 1, and adjust the priority of multiple routes with the same destination address. The smaller the hop count, the higher the priority.

[0063] The specific process of step 5 is as follows:

[0064] First check whether the neighbor corresponding to the Advertised Neighbor Main Address is a one-hop neighbor. If it is, no processing is performed. Otherwise, the following processing is performed:

[0065] If there is no entry in the routing table with R_dest_addr equal to Advertised Neighbor Main Address, a new routing entry is added, R_dest_addr in the routing entry is set to Advertised Neighbor Main Address, and a new route is added to the routing set, R_next_addr in the route is set to the node address of the forwarding message, R_last_addr is set to the Originator Address of the message, R_dist is set to the Hop Count in the message plus 1, R_time is equal to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority;

[0066] Otherwise, for the entry whose R_dest_addr is equal to the Advertised Neighbor Main Address, add a new route to the route collection, set R_next_addr in the route to the node address of the forwarding message, set R_last_addr to the Originator Address of the message, set R_dist to the Hop Count in the message plus 1, and set R_time to the current time plus TOP_HOLD_TIME; then adjust the R_priority of each route in the route collection according to R_dist, and the smaller the hop count, the higher the priority.

[0067] Step 6: When a node finds a new symmetric one-hop neighbor, it updates the route according to the following rules:

[0068] Add a route with the address of the new symmetric one-hop neighbor as the destination address, set the priority to the highest level, and reduce the priority of other existing routes with the address of the new symmetric one-hop neighbor as the destination address by one level.

[0069] The specific process of step 6 is as follows:

[0070] If there is no entry in the routing table with R_dest_addr equal to the address of the new symmetric one-hop neighbor, then a new routing entry is added, and R_dest_addr in the routing entry is set to the address of the new symmetric one-hop neighbor. A new route is added to the routing set, and R_next_addr in the route is set to the address of the new symmetric one-hop neighbor, R_last_addr is empty, R_dist is set to 1, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority.

[0071] Otherwise, for the entry whose R_dest_addr is equal to the address of the new symmetric one-hop neighbor, a new route is added to the route set, R_next_addr in the route is set to the address of the new symmetric one-hop neighbor, R_last_addr is empty, R_dist is set to 1, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority; for other routes in the route set, R_priority is reduced by one level compared to the current value.

[0072] Step 7: When a node finds that its symmetric one-hop neighbor becomes asymmetric, it updates the route according to the following rules:

[0073] For each routing table entry, check each route in the routing set of the routing table entry. If R_next_addr is this one-hop neighbor, delete the corresponding route; if the routing set of the table entry is not empty at the end, reorder the routes in the set based on the current priority to obtain a new priority; otherwise, delete the corresponding routing table entry.

[0074] The above process is described below with reference to the example in the accompanying drawings. In this example, nodes 0, 1, 3, 5 and 6 are MPR nodes.

[0075] exist Figure 1 In this example, node 1 generates a TC message, which includes node 2. This message passes through node 0 to node 4. At this time, node 4 records the route from node 0 to node 1, and also records the route from node 0 to node 2. This message also passes through nodes 6 and 5 to node 4. At this time, node 4 records the route from node 5 to node 1, and also records the route from node 5 to node 2.

[0076] exist Figure 2 In this example, node 6 generates a TC message, which includes node 7. This message passes through node 5 to node 4. At this time, node 4 records the route from node 5 to node 6 and the route from node 5 to node 7. This message also passes through nodes 1 and 0 to node 4. At this time, node 4 records the route from node 0 to node 6 and the route from node 0 to node 7.

[0077] exist Figure 3 In the example, node 3 generates a TC message, which includes nodes 2 and 7. This message passes through nodes 6 and 5 to reach node 4. At this time, node 4 records the route from node 5 to node 3, and also records the route from node 5 to node 2 and the route from node 5 to node 7. This message also passes through nodes 6, 1, and 0 to reach node 4. At this time, node 4 records the route from node 0 to node 3, and also records the route from node 0 to node 2 and the route from node 0 to node 7.

Claims

1. A method for quickly updating routing in an OLSR protocol, characterized in that: The process includes: Step 1, select the MPR node according to the MPR selection method, and the MPR node periodically generates a TC message, which contains the symmetric one-hop neighbors that are not MPRs; and define the node's routing table and repeat set, each entry in the routing table includes the destination address R_dest_addr of the route and the route set to the destination address, and the routing set records multiple routes, each route includes the next hop address R_next_addr, the last address before reaching the destination address R_last_addr, the number of hops R_dist, the effective time R_time and the priority R_priority; the repeat set includes the number of records D_rec_num, the originating address Originator Address of the message and the message sequence number Message Sequence Number; Step 2: When a node receives a TC message, it immediately forwards the message if it can be forwarded according to the current rules, and checks whether the TC message meets any of the following conditions. If it does, it does not participate in the routing update. If it does not, it is recorded in the duplicate set, and the number of records D_rec_num is increased by 1, and then step 3 is executed; 1) The combination of the message's Originator Address and Message Sequence Number has been recorded in the duplicate set, and the number of records of the same value of this combination exceeds the predefined threshold; 2) The Message Sequence Number of the message is smaller than the largest Message Sequence Number of all messages with the same OriginatorAddress recorded in the duplicate set; Step 3: Process the originator address in the message: If this is the first time this TC message is received, all routes with the Originator Address as the destination address in the current routing table are deleted; Add a route with Originator Address as the destination address. If this is the first time this TC message is received, the priority is set to the highest level. After the first time this TC message is received, the priority is lowered in turn. Step 4: Process the existing route with Originator Address as R_last_addr: If the number of records D_rec_num in the duplicate set is 1, the routes with Originator Address as R_last_addr in the route set of each routing table entry are deleted, and the R_priority of each route is adjusted according to the R_dist of the remaining routes in the set. The smaller the hop count, the higher the priority. Step 5: Process each Advertised Neighbor Main Address in the message: Add a route with the Advertised Neighbor Main Address as the destination address, record the hop count of this route as the hop count in the message plus 1, and adjust the priority of multiple routes with the same destination address. The smaller the hop count, the higher the priority.

2. The method for quickly updating routing in an OLSR protocol according to claim 1, characterized in that: The following processes are also included: Step 6: When a node finds a new symmetric one-hop neighbor, it updates the route according to the following rules: Add a route with the address of the new symmetric one-hop neighbor as the destination address, set the priority to the highest level, and reduce the priority of other existing routes with the address of the new symmetric one-hop neighbor as the destination address by one level.

3. A method for quickly updating routing in an OLSR protocol according to claim 1 or 2, characterized in that: The following processes are also included: Step 7: When a node finds that its symmetric one-hop neighbor becomes asymmetric, it updates the route according to the following rules: For each routing table entry, check each route in the routing set of the routing table entry. If R_next_addr is this one-hop neighbor, delete the corresponding route; if the routing set of the table entry is not empty at the end, reorder the routes in the set based on the current priority to obtain a new priority; otherwise, delete the corresponding routing table entry.

4. The method for quickly updating routing in an OLSR protocol according to claim 1, characterized in that: The specific process of step 3 is as follows: If there is no entry in the routing table with R_dest_addr equal to Originator Address, a new routing entry is added, R_dest_addr in the routing entry is set to Originator Address, and a new route is added, R_next_addr in the route is set to the node address of the forwarding message, that is, the source address in the IP header, R_last_addr is empty, R_dist is set to the hop count in the message, R_time is set to the current time plus the topology hold time TOP_HOLD_TIME, and R_priority is set to the highest priority; Otherwise, the entry with R_dest_addr equal to Originator Address is processed as follows: If the number of records in the duplicate set D_rec_num is 1, clear the routing set of the corresponding table entry; Add a new route to the route collection. In the route, R_next_addr is set to the node address of the forwarding message, R_last_addr is empty, R_dist is set to the Hop Count in the message, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is equal to the lowest priority in the route collection and one level lower.

5. The method for quickly updating routing in an OLSR protocol according to claim 4, characterized in that: The specific process of step 5 is as follows: First check whether the neighbor corresponding to the Advertised Neighbor Main Address is a one-hop neighbor. If it is, no processing is performed. Otherwise, the following processing is performed: If there is no entry in the routing table with R_dest_addr equal to Advertised Neighbor Main Address, a new routing entry is added, R_dest_addr in the routing entry is set to Advertised Neighbor Main Address, and a new route is added to the routing set, R_next_addr in the route is set to the node address of the forwarding message, R_last_addr is set to the Originator Address of the message, R_dist is set to the Hop Count in the message plus 1, R_time is equal to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority; Otherwise, for the entry whose R_dest_addr is equal to the Advertised Neighbor Main Address, add a new route to the route collection, set R_next_addr in the route to the node address of the forwarding message, set R_last_addr to the Originator Address of the message, set R_dist to the Hop Count in the message plus 1, and set R_time to the current time plus TOP_HOLD_TIME; then adjust the R_priority of each route in the route collection according to R_dist, and the smaller the hop count, the higher the priority.

6. The method for quickly updating routing in an OLSR protocol according to claim 5, characterized in that: The specific process of step 6 is as follows: If there is no entry in the routing table with R_dest_addr equal to the address of the new symmetric one-hop neighbor, then a new routing entry is added, and R_dest_addr in the routing entry is set to the address of the new symmetric one-hop neighbor. A new route is added to the routing set, and R_next_addr in the route is set to the address of the new symmetric one-hop neighbor, R_last_addr is empty, R_dist is set to 1, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority. Otherwise, for the entry whose R_dest_addr is equal to the address of the new symmetric one-hop neighbor, a new route is added to the route set, R_next_addr in the route is set to the address of the new symmetric one-hop neighbor, R_last_addr is empty, R_dist is set to 1, R_time is set to the current time plus TOP_HOLD_TIME, and R_priority is set to the highest priority; for other routes in the route set, R_priority is reduced by one level compared to the current value.

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