A routing protection method with high fault protection rate based on SDN

Abstract

The present invention discloses a routing protection method with a high fault protection rate based on a software defined network, which belongs to the field of Internet technology. By utilizing the advantages of SDN centralized control, the backup nodes and paths of all node pairs are calculated in advance, which can not only cope with most single network faults, but also will not bring too much time delay, thus solving the problem that the fault protection rate is not high and routing loops will occur in the existing routing protection scheme. The present invention can not only cope with most single fault problems in the network, but also has a smaller path stretching degree, and will not bring too much time delay. Therefore, the present invention can provide an effective solution for improving the self-healing property of SDN networks.

Description

Technical Field

[0001] The present invention belongs to the technical field of Internet, relates to an intra-domain routing protection scheme, and specifically relates to a routing protection method with a high fault protection rate based on SDN. Background Art

[0002] With the rise of artificial intelligence, real-time applications such as stock trading, VoIP, and online video are widely used in social life. Compared with traditional applications such as email transmission, these applications are more sensitive to network speed and fluency, and have higher requirements for the network's "self-healing ability". As the scale of the network continues to expand, network failures are inevitable. The current solution is to use adaptive dynamic routing protocols such as RIP, OSPF, and IS-IS. These protocols all solve failures through routing convergence, but the convergence time of RIP is on the order of 100 seconds and is suitable for small network environments. OSPF and IS-IS also take more than ten seconds or even more to complete convergence, and are also accompanied by routing loops or routing black holes. Therefore, the current routing protocols can no longer meet user needs, and how to improve the network's ability to cope with failures has become a scientific problem that needs to be solved urgently.

[0003] Software Defined Network (SDN) is a new type of network architecture that achieves centralized control by decoupling the control plane and forwarding plane in traditional network devices.

[0004] In the prior art, routing protection schemes are commonly used to improve the self-healing ability of the network. The routing protection scheme pre-calculates the possible fault nodes and the corresponding backup paths when designing the route. When a fault occurs, the strategy can cleverly avoid the fault node through the backup path and reach the destination node. The more typical routing protection schemes are NPC, U-turn, and Not-Via schemes. The NPC scheme has become the most popular routing protection scheme at present because of its simple deployment and no loops, but the fault protection rate of the NPC scheme is low and cannot achieve a good protection effect. The U-turn algorithm is improved based on the NPC algorithm. Although it improves the fault protection rate, it still cannot cope with most single network faults. Although the Not-Via scheme has a high fault protection rate, it is complex to implement and difficult to deploy in practice. Summary of the invention

[0005] Aiming at the problem that the fault protection rate of existing routing protection schemes is low and routing loops are prone to occur, the present invention proposes a routing protection method with a high fault protection rate based on software defined network.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a routing protection method with high fault protection rate based on SDN, comprising the following steps:

[0007] S1. Obtain the undirected connected graph G of the SDN network;

[0008] S2. Obtain a node pair (s, d) in the SDN network, traverse all neighbor nodes of the source node s, and determine its side branch backup nodes;

[0009] S3, calculate the backup path corresponding to each branch backup node according to the message forwarding rule, find the backup node according to the backup path and store it in the backup dictionary bn; and enter step S4, if it cannot be found, store the current node in the mark dictionary R, ​​and enter step S4;

[0010] S4, traverse all node pairs in the SDN network and repeat the operations of steps S2 to S3;

[0011] S5, obtain a node pair in the tag dictionary R, ​​traverse all neighbor nodes of the source node, determine whether there is a non-empty set of backup next hops from the neighbor node to the target node, if yes, set the tag value of the node to the first tag value, if not, set the tag value of the node to the second tag value; traverse all node pairs in the tag dictionary R, ​​and repeat the operation of S5;

[0012] S6. Sort all node pairs corresponding to the same target node in the tag dictionary R, ​​and sort them from large to small according to the degree of the source node corresponding to each node pair;

[0013] S7, according to the sorting of step S6, deleting the node pairs having the first tag value from the tag dictionary R;

[0014] S8, traverse all neighbor nodes of the source node s of the deleted node pair, calculate its backup path according to the message forwarding rule, and if it can be found, find the backup node according to the backup path, store it in the backup dictionary bn, and then set the mark value of the node formed by the node adjacent to the source node and the target node in the mark dictionary R to the first mark value;

[0015] S9, determining whether the tag dictionary R is an empty set, or whether all node pairs in the tag dictionary R have the second tag value, if so, proceeding to step S10, if not, returning to step S7;

[0016] S10. Determine whether there is a node pair without a backup next hop. If so, return to step S5. If not, output the final backup dictionary bn.

[0017] In steps S3 and S8, the message forwarding rules are:

[0018] If the optimal next hop of the current node is not a faulty node, forward the packet to its optimal next hop node; if the optimal next hop of the current node is a faulty node, forward the packet to its backup next hop node; if the current node receives a packet sent by its optimal next hop node, forward the packet to its backup next hop node.

[0019] In the step S3, the method for finding the backup node according to the backup path is as follows:

[0020] Calculate the costs of each backup path, and select the node corresponding to the backup path with the minimum cost as the backup node.

[0021] In the step S8, the method for finding the backup node according to the backup path is as follows:

[0022] Judge whether there is a side branch backup node in the backup path. If it exists, store the backup next hop corresponding to the side branch backup node into the backup dictionary bn; if there is no side branch backup node, calculate the costs of each backup path, and select the node corresponding to the backup path with the minimum cost as the backup node and store it into the backup dictionary bn.

[0023] In the step S2, the method for determining the side branch backup node is as follows:

[0024] For the node pair (s, d), traverse all neighbor nodes n of the source node s; if in the reverse shortest path tree rooted at the destination node d, the level of the source node s is the same as the level of the destination node n, and in the reverse shortest path tree rooted at the destination node d, the parent node of the source node s is different from the parent node of the node n, that is, level(d, s) = level(d, n) and father(d, s)! = father(d, n) hold simultaneously, then incorporate the node n into the backup next hop node set M; if in the reverse shortest path tree rooted at the node d, the level of the node s is greater than the level of the node n, that is, level(d, s)>level(d, n) holds, then incorporate the node n into the backup next hop node set M; if in the reverse shortest path tree rooted at the node d, the level of the node s is less than the level of the node n, and the parent node of the node s is not an ancestor node of the node n, that is, level(d, s)<level(d, n) and father(d, s) hold simultaneously, then incorporate the node n into the backup next hop node set M;

[0025] Traverse the optional backup node m in the backup next hop node set M in sequence. If in the reverse shortest path tree with node d as the root, there exists a subtree root node of node m that is different from the subtree root node of node s, that is, subroot(d,m)≠subroot(d,s), then node m is retained in M ​​as a branch backup node of node s, and other nodes are deleted.

[0026] The first mark value is 1, and the second mark value is 0.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention proposes a routing protection method with a high fault protection rate based on software defined network. By utilizing the centralized control characteristics of SDN, the global calculation of backup nodes can be performed for all node pairs in the network in advance. When a node in the network fails, the forwarding plane only needs to forward the message according to the backup path calculated in advance, and the message can be smoothly sent to the destination node by avoiding the failed node. Therefore, the present invention can not only cope with most single network failures, but also will not cause excessive time delays by calculating the backup next hop nodes and paths of all node pairs in advance, and provides an effective solution for improving the self-healing property of SDN networks;

[0029] 2. The present invention can not only cope with most single fault problems in the network, but also has a smaller path stretching degree and will not cause excessive time delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of a routing protection method with a high fault protection rate based on a software defined network of the present invention.

[0031] Figure 2 1 is a schematic diagram of the network topology structure rspt(d) of an embodiment of the present invention. In the figure, the two nodes connected by the dotted line represent neighbor nodes in the actual network G. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] For ease of description, in the present invention, the network is described as an undirected connected graph G = (V, E), where V is the set of routers (nodes) in the network, and E is the set of links (edges) in the network. Any node in the network can be represented as v∈V, v.lasthop represents the previous hop node of node v, v.besthop represents the best next hop node of node v, nei(v) represents all neighbor nodes of node v, rspt(v) represents the reverse shortest path tree with node v as the root, level(v,x) represents the level of node x in rspt(v), father(v,x) represents the father node of node x in rspt(v), ance(v,x) represents the set of all ancestor nodes of node x in rspt(v), and subroot(v,x) represents the subtree root node of node x in rspt(v). For bn(x,y) represents the set of backup next hops from node x to node y, besthop(x,y) represents the best next hop from node x to node y, sp(x,y) represents the shortest path from node x to node y, and bp(x,y) represents the backup forwarding path from node x to node y. path is used to store the nodes that the message passes through. Because the same node pair may generate multiple backup paths during the calculation process, path(s,d,m) is used to represent the backup path of the node pair (s,d) through the backup node m.

[0034] like Figure 1 As shown, an embodiment of the present invention provides a routing protection method with a high fault protection rate based on SDN, comprising the following steps:

[0035] S1. Obtain an undirected connected graph G of the SDN network.

[0036] S2. Obtain a node pair (s, d) in the SDN network, traverse all neighbor nodes of the source node s, and determine its side branch backup nodes.

[0037] In step S2, the method for determining the side branch backup node is:

[0038] For the node pair (s, d), traverse all neighbor nodes n of the source node s, where n∈nei(s);

[0039] (1) If in the reverse shortest path tree with target node d as the root, the level of source node s is the same as that of target node n, and in the reverse shortest path tree with target node d as the root, the parent node of source node s is different from the parent node of node n, that is, level(d,s)=level(d,n) and father(d,s)!=father(d,n) are both true, then node n is incorporated into the backup next hop node set M;

[0040] (2) If in the reverse shortest path tree rooted at node d, the level of node s is greater than the level of node n, i.e., level(d, s) > level(d, n) holds, then incorporate node n into the backup next-hop node set M;

[0041] (3) If in the reverse shortest path tree rooted at node d, the level of node s is less than the level of node n, and the parent node of node s is not an ancestor node of node n, i.e., level(d, s) < level(d, n) and father(d, s) both hold, then incorporate node n into the backup next-hop node set M;

[0042] After obtaining the backup next-hop node set M through the above (1)-(3), traverse the optional backup nodes m in the backup next-hop node set M in sequence. If in the reverse shortest path tree rooted at node d, there exists a node such that the root node of the subtree of m is different from the root node of the subtree of s, i.e., subroot(d, m) ≠ subroot(d, s) holds, then retain node m as a side-branch backup node of node s in M and delete the other nodes in M.

[0043] S3. Calculate the backup paths corresponding to each side-branch backup node according to the packet forwarding rule, find the backup nodes according to the backup paths and store them in the backup dictionary bn; and enter step S4. If not found, store the current node in the marker dictionary R and enter step S4.

[0044] In this embodiment, a packet forwarding rule needs to be formulated. Any node in the network will abide by the following forwarding rule after receiving a packet. The packet forwarding rule is:

[0045] (1) If the optimal next-hop of the current node is not a failed node, then forward the packet to its optimal next-hop node, i.e., if v.besthop ≠ failed_node, then v ← v.besthop;

[0046] (2) If the optimal next-hop of the current node is a failed node, then forward the packet to its backup next-hop node, i.e., if v.besthop = failed_node, then v ← v.backhop;

[0047] (3) If the current node receives a message from its optimal next-hop node, it will forward the message to its backup node, that is, if v.lasthop = v.besthop, then v←v.backhop. v.backhop represents the backup next-hop list of node v (which has been calculated and stored in the first and second rounds of calculation). This step is mainly to set up this situation: if the previous hop node of node v is its optimal next-hop node (that is, v receives a message from its optimal next-hop node), it means that a faulty node has been encountered before, then node v will point to its backup node v.backhop (that is, v will send the message to its backup node).

[0048] In addition, during the forwarding process, before the message passes through a node v, it is determined whether v∈path holds. When v∈path holds, if any of the following conditions holds: v.lasthop≠v.besthop or path.count(v)≥2, it is determined that a loop occurs.

[0049] In this embodiment, the method for determining the backup path according to the forwarding rule is: if the destination node cannot be reached, then traverse the backup node backhop of each node in the path. If subroot(d, backhop)≠subroot(d,s) holds, then execute the message forwarding rule with backhop as the source node to obtain the backup path path again.

[0050] In addition, in this embodiment, the method for finding the backup node according to the backup path is:

[0051] Calculate the cost of each backup path and select the node corresponding to the backup path with the smallest cost as the backup node.

[0052] S4. Traverse all node pairs in the SDN network and repeat the operations of steps S2 to S3.

[0053] At this point, the first round of calculations is completed, and backup nodes have been found for some node pairs in the SDN network. It is necessary to obtain the backup nodes of the remaining node pairs without backup nodes, that is, the node pairs in the marking dictionary R, ​​through the second round of continued calculation.

[0054] S5. Get a node pair in the tag dictionary R, ​​traverse all neighbor nodes of the source node, and determine whether there is a non-empty set of backup next hops from the neighbor node to the target node, that is, whether there is n∈nei(s) that meets If yes, then the tag value of the node is set to the first tag value; if no, then the tag value of the node is set to the second tag value; all node pairs in the tag dictionary R are traversed, and the operation of S5 is repeated.

[0055] Specifically, the first mark value is 1, that is, R(s, d)=1; the second mark value is 0, that is, R(s, d)=0.

[0056] S6. Sort all node pairs corresponding to the same target node in the tag dictionary R. The sorting method is to sort from large to small according to the degree of the source node corresponding to each node pair.

[0057] In this embodiment, the degree of a node refers to the number of branches of the node. If the degree of a node is 2, it means that the node has two adjacent neighbor nodes. By sorting the node pairs according to the degree from large to small, for multiple node pairs of the same target node, the node pairs with more branches can be placed in front, because the marking dictionary is traversed sequentially from the first node pair, so the node pairs with larger branches will be popped up first, and then the values ​​of the neighbor node pairs adjacent to the source node and without backup nodes will be marked as 1, so that more node pairs can be marked as 1, which will improve the performance of the entire network and avoid the situation of no backup nodes caused by the calculation order as much as possible. In addition, in this embodiment, step S5 and step S6 can also be interchanged.

[0058] S7, according to the sorting of step S6, the node pair (s, d) with the first mark is deleted from the mark dictionary R;

[0059] S8. Traverse all neighbor nodes of the source node s of the deleted node pair, calculate its backup path according to the message forwarding rules, and if it can be found, find the backup node according to the backup path and store it in the backup dictionary bn. Then set the mark value of the node pair formed by the node nei(s) adjacent to the source node and the target node d in the mark dictionary R to the first mark value, that is, R(nei(s),d)=1.

[0060] In step S8, the method for finding the backup node according to the backup path is:

[0061] Determine whether there is a side branch backup node in the backup path. If so, store the backup next hop corresponding to the side branch backup node in the backup dictionary bn; if there is no side branch backup node, calculate the cost of each backup path, select the node corresponding to the backup path with the smallest cost as the backup node and store it in the backup dictionary bn.

[0062] S9. Determine whether the tag dictionary R is an empty set, or whether the tag values ​​of all node pairs in the tag dictionary R are the second tag value. If so, proceed to step S10; if not, return to step S7.

[0063] In this embodiment, if it is determined whether the marking dictionary R is an empty set, or whether the marking values of all node pairs in the marking dictionary R are all the second marking value, the second-round calculation is completed. At this time, if the marking dictionary R is not an empty set, it indicates that there are still node pairs for which backup nodes have not been found. In this case, it is necessary to return to step S5 to re-perform the second-round calculation.

[0064] S10. Determine whether there are node pairs without backup nodes. If so, return to step S5 and loop through steps S5 to S8 until all node pairs in the marking dictionary R have backup nodes. If not, output the final backup dictionary bn.

[0065] Next, taking the Figure 2 network shown as an example, the steps of this embodiment of the present invention will be described.

[0066] Step 1: Obtain the network G, as Figure 2 shown;

[0067] Step 2: Taking (s, d) as an example, traverse all neighbor nodes {m, i, e, g, n} of s to determine its branch backup nodes.

[0068] The specific method is to create M to store the backup nodes of the node pair (s, d), and M is initially empty.

[0069] (1) Node g is a neighbor node of s and both level(d, s) = level(d, g) and father(d, s)! = father(d, g) hold. Therefore, node g can be incorporated into M.

[0070] (2) Node e is a neighbor node of node s and level(d, s)>level(d, e) holds. Therefore, node e can be incorporated into M.

[0071] (3) Node n is a neighbor node of node s, father(d, s) = m. level(d, s)<level(d, n) and both hold. Therefore, node n can be incorporated into M.

[0072] Through the above (1) to (3), at this time M = {g, e, n}, traverse the optional backup nodes g, e, n in M. subroot(d, g) = subroot(d, s) = a, subroot(d, e) = subroot(d, n) = b≠subroot(d, s). Therefore, the determined branch backup nodes are: M = {e, n}.

[0073] Step 3: Formulate a message forwarding rule to obtain its backup nodes.

[0074] First, in the two backup paths obtained according to the message forwarding rules, no loop occurs at the nodes that the message passes through;

[0075] Secondly, the two backup paths corresponding to e and n can both reach the destination node d.

[0076] Moreover, when the optimal next-hop node a of (s, d) fails, two backup paths can be obtained, path (s, d, e) = (s, e, b, d) and path (s, d, n) = (s, n, k, f, b, d).

[0077] Then, calculate the path costs of path(s,d,e) and path(s,d,n) respectively, select the node with the smallest cost as the backup next hop and store it in bn(s,d). Here, it is assumed that the cost corresponding to path(s,d,e) is the smallest, so the backup node of node pair (s,d) is bn(s,d)=e.

[0078] Step 4: Repeat steps 2 to 4 above to traverse all node pairs. The first round of calculation is completed.

[0079] Step 5: Second round of calculation: Create a marking dictionary R to store the node pairs that do not have backup nodes in the first round of calculation.

[0080] The second round of calculation takes the node pair (h, d) as an example, assuming nei(h)={a,g,m} and Traverse the neighboring nodes m and g of node h, Therefore, R(h,d)=1, R(m,d)=0.

[0081] Step 6: Sort the node pairs in the label dictionary R according to the degree of the source node from large to small, with the node pair (h, d) ranked first.

[0082] Step 7: Pop out the node pair (h, d) in the label dictionary R.

[0083] Step 8: Use the message forwarding rule to calculate the backup path of (h, d), and get path(h, d, g) = (h, g, s, m, s, e, b, d). There is a branch backup node b in path(h, d, g), so store node g in bn(h, d).

[0084] In addition, the node adjacent to the source node h is m, so let R(m,d)=1.

[0085] Step 9: Repeat steps 7-8 until Or if all the marked values ​​in R are 0, the second round of calculation is completed.

[0086] Step 10: If there is still a node pair without a backup next hop, repeat steps 4-9.

[0087] The present invention proposes a routing protection method with a high fault protection rate based on software defined network, which takes advantage of SDN centralized control and calculates the backup next hop nodes and paths of all node pairs in advance, which can not only cope with most single network faults, but also does not cause excessive time delay. Therefore, the present invention can provide an effective solution for improving the self-healing property of SDN network.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A routing protection method with high fault protection rate based on SDN, characterized in that: The following steps are involved: S1. Obtain the undirected connected graph G of the SDN network; S2, obtain a node pair (s, d) in the SDN network, traverse all neighbor nodes of the source node s, and determine its side branch backup nodes; S3, calculate the backup path corresponding to each branch backup node according to the message forwarding rule, find the backup node according to the backup path and store it in the backup dictionary bn; And go to step S4, if it cannot be found, store the current node in the tag dictionary R, ​​and go to step S4; S4, traverse all node pairs in the SDN network and repeat the operations of steps S2 to S3; S5, obtain a node pair in the tag dictionary R, ​​traverse all neighbor nodes of the source node, determine whether there is a non-empty set of backup next hops from the neighbor node to the target node, if yes, set the tag value of the node to the first tag value, if not, set the tag value of the node to the second tag value; traverse all node pairs in the tag dictionary R, ​​and repeat the operation of S5; S6. Sort all node pairs corresponding to the same target node in the tag dictionary R, ​​and sort them in descending order according to the degree of the source node corresponding to each node pair; the degree of the source node refers to the number of branches of the source node; S7, according to the sorting of step S6, deleting the node pairs having the first tag value from the tag dictionary R; S8, traverse all neighbor nodes of the source node s of the deleted node pair, calculate its backup path according to the message forwarding rule, and if it can be found, find the backup node according to the backup path, store it in the backup dictionary bn, and then set the mark value of the node formed by the node adjacent to the source node and the target node in the mark dictionary R to the first mark value; S9, determining whether the tag dictionary R is an empty set, or whether all node pairs in the tag dictionary R have the second tag value, if so, proceeding to step S10, if not, returning to step S7; S10, determine whether there is a node pair without a backup next hop, if so, return to step S5, if not, output the final backup dictionary bn; in steps S3 and S8, the message forwarding rule is: If the optimal next hop of the current node is not a faulty node, the message is forwarded to its optimal next hop node; if the optimal next hop of the current node is a faulty node, the message is forwarded to its backup next hop node; If the current node receives a message sent by its optimal next-hop node, it forwards the message to its backup next-hop node.

2. According to claim 1, a routing protection method with high fault protection rate based on SDN is characterized in that: In step S3, the method for finding the backup node according to the backup path is: Calculate the cost of each backup path and select the node corresponding to the backup path with the smallest cost as the backup node.

3. The routing protection method with high fault protection rate based on SDN according to claim 1, characterized in that: In step S8, the method for finding the backup node according to the backup path is: Determine whether there is a side branch backup node in the backup path. If so, store the backup next hop corresponding to the side branch backup node in the backup dictionary bn; if there is no side branch backup node, calculate the cost of each backup path, select the node corresponding to the backup path with the smallest cost as the backup node and store it in the backup dictionary bn.

4. The routing protection method with high fault protection rate based on SDN according to claim 1, characterized in that: In step S2, the method for determining the side branch backup node is: Node pair (s,d) , traverse all neighbor nodes of the source node s n ; If in the reverse shortest path tree with the target node d as the root, the level of the source node s is the same as the level of the target node n, and in the reverse shortest path tree with the target node d as the root, the parent node of the source node s is different from the parent node of the node n, that is and If both are true, then the node n Merge into the backup next hop node set M In the reverse shortest path tree with node d as the root, the level of node s is greater than the level of node n, that is, If established, the node n Merge into the backup next hop node set M In the reverse shortest path tree with node d as the root, if the level of node s is less than the level of node n, and the parent node of node s is not the ancestor node of node n, that is If both are true, then the node n Merge into the backup next hop node set M middle; Traverse the backup next hop node set in sequence M Optional backup nodes in m , if in the reverse shortest path tree with node d as the root, there is a subtree root node of node m that is different from the subtree root node of node s, that is If established, the node m As a node s The branch backup node is retained until M and delete other nodes.

5. The routing protection method with high fault protection rate based on SDN according to claim 1, characterized in that: The first mark value is 1, and the second mark value is 0.

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