A Forwarding Path Method for a Reliable Virtual Network

Abstract

The present invention provides a method for forwarding paths of a reliable virtual network, which solves the problem of how to construct a reliable virtual forwarding path and can satisfy that different types of service traffic do not interfere with each other and can be reliably forwarded. By referring to the method of ECMP sub-topology segmentation to ensure the non-correlation between paths, the present invention first obtains non-correlated NFP backup paths within the topological sub-region through the maximum redundant tree (MRT) cut graph method on the premise of considering reliability indicators. Secondly, the divided sub-topologies are cut off in the global topology, and the remaining feasible sub-topology regions are repeatedly searched, which not only ensures the non-correlation between NFP paths in the same region, but also ensures the non-correlation of NFP between different regions, thus forming a reliable virtual forwarding path.

Description

Technical Field

[0001] The present invention relates to the technical field of virtual network, and particularly to a method for forwarding paths of a reliable virtual network, which is applicable to the 5G industrial control field. Background Art

[0002] In a telecommunication network, 5G can open network capabilities such as location services, service configuration, content caching, etc. through virtualization and cloudification technologies, provide guaranteed network capabilities for upcoming network services (NS), and achieve efficient network load management and resource optimization through core network resource management and orchestration.

[0003] As one of the important application scenarios of 5G, the industry has characteristics such as a variety of service types and more stringent requirements. The Internet Engineering Task Force proposed a reference point model under the cloudification of industrial Internet - the Abstract and Control Framework for Traffic Engineering Networks (ACTN) in RFC8453. ACTN jointly considers node processing and path capabilities, adds a layer of virtual network operators between traditional customers and network infrastructure providers, and uses virtualization technologies such as software - defined network (SDN) and network function virtualization (NFV) to integrate underlying communication resources, and provides diverse and customized virtual network services in a sliced form to users. Further, to support the virtual network function forwarding graph orchestration for specific services in NFV, the concepts of node processing and virtual forwarding path (NFP) are refined. It can be seen that when designing customized network services, it is necessary to ensure the processing reliability of the virtual forwarding path. Secondly, the traffic load pressure at the core is large, and it is also an important goal to achieve load balancing by dispersing traffic flows through redundant paths.

[0004] Currently, most of the research on the reliability of NFP designs reliability solutions with the goal of optimizing underlying resources. However, in industrial scenarios, with the business as the core, more attention is paid to the matching and effective response of business requirements. In addition, most of the current work focuses on ensuring the reliability of a single point or one - side, and relatively little work is done on researching the overall path reliability. It is difficult to effectively meet the business requirements in the 5G industrial control scenario from the methods of single - node protection and single - link protection. Summary of the Invention

[0005] The present invention provides a method for forwarding paths of a reliable virtual network, which solves the problem of how to construct a reliable virtual forwarding path and can meet the requirement that different types of service flows do not interfere with each other and can be reliably forwarded.

[0006] The present invention is realized through the following technical solutions.

[0007] A method for forwarding paths of a reliable virtual network, characterized by comprising:

[0008] Step 1. Determine the reliability of the NFP path according to the reliability indexes of the virtual network function nodes and virtual links and in combination with the correlation between paths.

[0009] Step 2. According to the reliability indexes of the nodes and links and in combination with the access order, determine that the NFP path first searched by the ECMP algorithm is the optimal main path direction.

[0010] Step 3. Mark the nodes in the virtual network topology and calculate the positions of cut points and cut edges in the topology.

[0011] Step 4. Along the optimal path direction, starting from the source node according to the reliability indexes of the nodes and links, sequentially add the maximum reliable rings in the logical order of the nodes. When adding the maximum reliable rings, ensure that the reliable rings do not contain the cut points and cut edges, and search for a reliable topological subgraph with the minimum correlation between the backup path and the main path.

[0012] Step 5. Determine whether the destination node is in the reliable topological subgraph. If it has been accessed, stop the search. If it has not been accessed yet, continue the search with the point farthest from the source node in the default NFP as the new starting point until the destination node is traversed, and finally search for a topological subgraph with the optimal reliability.

[0013] Step 6. Construct red / blue redundant paths in the topological subgraph with the optimal reliability, and only allow the cut points and cut edges to be shared, ensuring that the two redundant NFP paths in the same topological subgraph are maximally non-correlated and reliable, thereby determining the reliability index of the topological subgraph and performing regional coloring and marking.

[0014] Step 7. Divide the point and edge elements in the marked area in the global topology, and repeat Steps 4 to 6 until the destination end node is reached, obtaining multiple colored areas with non-correlated and different reliability capabilities.

[0015] Advantages of the present invention:

[0016] The present invention draws on the practice of the ECMP sub-cut topology to ensure the non-correlation between paths. On the premise of considering the reliability index, first obtain the non-correlated NFP backup paths within the topological sub-region through the maximum redundant tree (MRT) cut graph method, and then cut off the divided sub-topologies in the global topology and repeat the search for the remaining feasible sub-topological regions, which not only ensures the non-correlation between the NFP paths within the same region but also ensures the non-correlation between the NFP paths in different regions, forming a reliable virtual forwarding path. Under the deeper integration with different services in the industrial control scenario, it can provide more reliable service forwarding in the face of sudden failures. Moreover, the backup NFP paths can also provide load balancing capabilities for services with different reliability requirements during normal network operation, better meeting the service requirements in the 5G industrial control scenario. Description of the Drawings

[0017] Figure 1 Flowchart of the forwarding path method for the reliable virtual network of the present invention.

[0018] Figure 2 Schematic diagram of the virtual network function topology of the present invention.

[0019] Figure 3 Schematic diagram of the cut point and cut edge search of the present invention.

[0020] Figure 4 Schematic diagram of the maximum redundant tree cut graph method of the present invention.

[0021] Figure 5 Schematic diagram of the topological subgraph of the present invention. Detailed implementation manner

[0022] The present invention will be described in detail below with reference to the accompanying drawings.

[0023] As Figure 1 shown, a method for the forwarding path of a reliable virtual network in this embodiment specifically includes:

[0024] Step 1: Determine the reliability of the NFP path according to the reliability indexes of the virtual network function nodes and virtual links, and combining the correlation between paths;

[0025] The reliability description of the processing capabilities of the virtual network function (VNF) and virtual link (V-Link) can be modeled from multiple dimensions. In this embodiment, in terms of the node reliability index, its processing capability is reflected by the throughput; in terms of the virtual link reliability index, considering that many wide-area control scenarios in industry use wireless link transmission, the signal-to-interference-plus-noise ratio (SINR) model of the wireless link is used for its analysis;

[0026] Based on this, the reliability formula of the NFP path is specifically as follows:

[0027]

[0028] Among them, A i represents the reliability index of the virtual network function node, R ij represents the reliability index of the virtual link, φ is the probability of natural failure of the node due to physical reasons, RTT is the round-trip time of the message segment, R b is the maximum transmission rate, p is the packet loss rate of the node, η is the noise power, B is the bandwidth, g kj is the propagation gain between nodes k and j, p kh (t) is the transmission power of node k to node h at time t, is the reliability index of the NFP path determined by the reliability indexes of the virtual network function node and virtual link, is the correlation coefficient between two NFPs. is the u-th path from the source to the destination node, consisting of m segments of links. is the link reliability of a segment consisting of an output node and a link, and α is the weight of each in this segment of the link.

[0029] Step 2: According to the access order and the reliability indexes of nodes and links, determine that the NFP path first searched by the ECMP (Equal-Cost Multi-Path) algorithm is the optimal main path direction.

[0030] During specific implementation, as Figure 2 shown, since the "shortest" rule is usually followed when searching for paths, that is, the smaller the sum of Cost values, the better the path. Therefore, the Cost value representing reliability is obtained by taking the logarithm of the result of the actual model, and the smaller the value, the better the reliability performance. The nodes S and D represent the source node and the destination node respectively, and the intermediate nodes represent different virtual network functions (VNFs) and backup nodes with similar functions. VNF nodes with different functions cannot back up each other, and it is assumed that according to the business logic order, the access order of VNFs is in sequence P rA >P rB >P rC >P rD and traverse in sequence.

[0031]

[0032] Among them, can represent the Cost values of each segment of the link. ECMP searches for the default NFP through the Shortest Path First (SPF) algorithm according to the sequential labels of the nodes. This NFP represents the most reliable path from the source to the destination when the network is running normally.

[0033] Step 3: Mark the nodes in the reliable virtual network topology and calculate the positions of cut points and cut edges in the topology.

[0034] In this embodiment, the nodes in the topology are marked using the Depth-First Search (DFS) and LowPoint algorithms. Specifically: First, start DFS traversal from the source node, and mark the DFS value D[x] of each node in the topology, indicating the time node when the node is visited. Secondly, mark the LowPoint value L[x] of each node through the LowPoint algorithm.

[0035] In this embodiment, as Figure 3 shown, the calculation of the positions of cut points and cut edges in the topology is specifically as follows: Search for the cut points and cut edges in the topology, and make judgments according to the following judgment basis:

[0036]

[0037] There are two cases where x is a cut point. The first case is that x is not the root node, x has child nodes, and L[child nodes of x] ≥ D[x]; the second case is that x is the root node and x has at least two or more child nodes; when the cut point and the edges entering the cut point are deleted, the graph will be divided into two parts;

[0038] The case where x→y is a cut edge is L[y] > D[x], indicating that the child node y has no back edge that can trace back to the parent node x. Once the edge x→y is deleted, two unconnected parts are formed;

[0039] Take Figure 3 the order shown as an example. The first number on each node represents the reliability of the link formed between the nodes value, the second numerical value represents the L[x] value, and the last numerical value represents the access sequence number of the node marked with D[x] in the order of business logic. Then, mark L[x] for each node according to the rules. At the initial moment, L[S] = 0. The node A1 has not marked the subsequent tree edges yet and does not know the situation of the back edges. Therefore, L[A1] = D[A1] = 1. By analogy, after marking L[x] = D[x] for B1, C, and B3, when accessing the node A2, since A2 has two back edges, namely A2→A1 and A2→S. At this time, comparing the D[A2] value of A2 itself, the L[A1] values and L[S] values of the two back edges, it is found that L[S] = 0 < L[A1] = 1 < D[A2] = 5. Therefore, L[A2] = L[S] = 0. At this time, for the previous node B3, it is found that there is a smaller L[A2] = 0 value in its tree edges. Therefore, update its own L[B3] to make L[B3] = L[A2] = 0. The same update occurs in the nodes C, B1, and A1.

[0040] Step 4: Along the optimal path direction, starting from the source node, add the maximum reliable loop in sequence according to the reliability indicators of the nodes and links. When adding the maximum reliable loop, make the reliable loop not contain the cut point and the cut edge, and search for a reliable topological subgraph with the minimum correlation between the backup path and the main path;

[0041] Specifically: Taking the source node as the root R, search for a path loop that can return to R starting from R according to the VNF order. Among them, when searching at the k-th stage, the search range can only be within the VNFs with numbers less than k. If there is no such loop, then move forward one step along the default NFP and continue the search. If there is such a loop, then select the loop with the maximum reliability composed of each segment of the link, record the points and edge elements in the loop as the visited state, and then continue the search for the next stage loop. Starting from the visited nodes, the condition is that it can return to the visited nodes. Among them, it is judged whether to search along the NFP direction according to whether a new intersection point can be generated with the default NFP.

[0042] In this embodiment, when searching for the loopback, the search target is that the reliability difference between the redundant NFP and the optimal default NFP is minimized:

[0043]

[0044] Among them, is the reliability index of the default NFP, s in n is the reliability index of the farthest node from the source node to each stage of the default NFP when searching for the maximum reliable loop from stage 1 to stage n, and u n is the decision of the maximum reliable loop finally selected after searching all feasible loops in each stage.

[0045] Taking Figure 4 shown as an example, at the initial stage, the source node S is included in the set V of visited nodes G′ , marked as visited, and determined to become a part of the topological subgraph. When k = 1, search for the maximum reliable loop among the nodes with node number P r ≤k. The nodes that meet the conditions are only node S, A1, and A2. The loop that starts from the visited node S and returns to the visited node S is only Therefore, the loop with the highest reliability is At this time, the farthest point from S to is A1. Excluding the links that coincide with the default NFP, the minimum cost is 2, that is, the reliability index s 1 of the first stage is 2, and the path index Write the elements in the loop into the temporary sets V temp and E temp . V temp ={S, A 1 , A 2}, And perform the V temp ∩V 0 judgment to determine whether there is a new intersection point other than the source node S between the loop and the default NFP. It is found that there is a new intersection point A1, which means the search direction is correct. Store the elements in the temporary set into the set of visited elements, and update V G′ to V G′ ={S, A 1 , A 2}, and update E G′ to If not, the loop is invalid, and V temp and E temp are emptied, and follow the next hop of the default NFP to enter the k = 2 stage to continue the search.

[0046] Step 5: Determine whether the destination node is in the reliable topological subgraph. If it has been visited, stop the search. If it has not been visited yet, continue the search with the point farthest from the source node in the default NFP as the new starting point until the destination node is traversed, and finally search out a topological subgraph with the optimal reliability;

[0047] Step 6: Construct red / blue redundant paths in the topological subgraph with the optimal reliability, only allowing cut points and cut edges to be shared, ensuring that the two redundant NFPs in the same topological subgraph are maximally non - related and reliable, thereby determining the reliability index of the topological subgraph and performing regional coloring and marking;

[0048] In this embodiment, the reliability index of the topological subgraph is determined by the following formula:

[0049]

[0050] Where: is the reliability of the regional coloring and marking number (such as the red region number), is the reliability index of the red path, is the reliability index of the blue path.

[0051] As Figure 5 shown, assume that node B1 in the default NFP fails, that is, A1 cannot forward traffic to B1, then the redundant NFP can be quickly switched at A1, {A 1 -A 2 -B 2 -B 3 -C - D 2 -D}. Except for the cut point C, this redundant NFP is maximally non - related to the default NFP, and the cost sum of its links has the smallest reliability difference from the default SFC compared with other NFP backup paths. Among them, B2 and B3 have duplicate functions, and node B3 can be regarded as a simple forwarding node. It can be seen that this method will increase a certain number of hops in some cases in exchange for reliability. Finally, color - code and mark the sub - topology, and the optimal reliability performance index is denoted as Assume that the Cost is converted into a reliability percentage of 100% - Cost%, then the reliabilities of the red and blue paths converted into percentages are respectively:

[0052]

[0053] Calculate the reliability performance index of this sub - topology as:

[0054]

[0055] Step 7: Divide from the points and edge elements in the marked area in the global topology, and repeat Steps 4 to 6 until the destination end node is reached, obtaining multiple colored areas with non - related and different reliability capabilities;

[0056] In specific implementation, number (color) these areas with non - related and different processing capabilities in sequence, and sort them from the most reliable to the lowest reliable that can be searched out in ascending order, such as

[0057] In summary, the above are only the preferred examples of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for forwarding paths of a reliable virtual network, characterized in that, it includes: Step 1: Determine the reliability of the NFP path according to the reliability indicators of virtual network function nodes and virtual links, and combining the relevance between paths; the specific formula for the reliability of the NFP path is as follows: Among them, A i represents the reliability index of the virtual network function node, R ij represents the reliability index of the virtual link, is the probability of natural failure of the node due to physical reasons, RTT is the round-trip time of the packet segment, R b is the maximum transmission rate, p is the packet loss rate of the node, η is the noise power, B is the bandwidth, g kj is the propagation gain between nodes k and j, p kh (t) is the transmission power of node k to node h at time t, is the reliability index of the NFP path determined by the reliability indices of the virtual network function node and the virtual link, is the correlation coefficient between two NFPs, is the u-th path from the source to the destination node, consisting of m segments of links in total, is the link reliability composed of an output node and a link, and α is the weight of each in this segment of the link; Step 2: Determine the optimal main path direction for the NFP path first searched by the ECMP algorithm according to the reliability indicators of the nodes and links, and combining the access order; Step 3: Mark the nodes in the virtual network topology and calculate the positions of cut points and cut edges in the topology; Step 4: Along the optimal path direction, starting from the source node according to the reliability indicators of the nodes and links, add the maximum reliable loop in turn according to the logical order of the nodes. When adding the maximum reliable loop, ensure that the reliable loop does not contain the cut point and the cut edge, and search for a reliable topological subgraph with the minimum correlation between the backup path and the main path; Step 5: Determine whether the destination node is in the reliable topological subgraph. If it has been accessed, stop the search. If it has not been accessed yet, continue the search with the point farthest from the source node in the default NFP as the new starting point until the destination node is traversed, and finally search for a topological subgraph with the optimal reliability; Step 6: Construct red / blue redundant paths in the topological subgraph with the optimal reliability, only allowing cut points and cut edges to be shared, ensuring that the two redundant NFP in the same topological subgraph are maximally non-correlated and reliable, thereby determining the reliability indicator of this topological subgraph and performing regional coloring marking; Step 7: Split the points and edge elements in the marked area in the global topology, and repeat Steps 4 to 6 until reaching the destination end node to obtain multiple colored areas with non-correlated and different reliability capabilities.

2. The method for forwarding paths of a reliable virtual network according to claim 1, characterized in that, the ECMP algorithm searches for the default NFP through the shortest path first (SPF) algorithm according to the sequential labels of the nodes: Among them, represents the Cost value of each link segment.

3. The method for forwarding paths of a reliable virtual network according to claim 1 or 2, characterized in that, the nodes in the topology are marked by using depth-first search (DFS) and LowPoint algorithm, specifically: first, perform DFS traversal starting from the source node, and mark the DFS value D[x] of each node in the topology, indicating the time node when the node is accessed. Secondly, mark the LowPoint value L[x] of each node through the LowPoint algorithm.

4. The method for forwarding paths of a reliable virtual network according to claim 3, characterized in that, the calculation of the positions of cut points and cut edges in the topology is specifically: search for the cut points and cut edges in the topology, and make judgments according to the following judgment basis: There are two cases where x is a cut point. The first case is that x is not the root node, x has child nodes, and satisfies L[the child nodes of x] ≥ D[x]; the second case is that x is the root node and x has at least two or more child nodes; when deleting the cut point and the edge entering the cut point, the graph forms two parts; The situation where x→y is a cut edge is satisfied when L[y] > D[x], indicating that there is no backward edge from the child node y that can trace back to the parent node x. Once the edge x→y is deleted, two unconnected parts are formed.

5. The forwarding path method of the reliable virtual network as claimed in claim 4, characterized in that when searching for loops, the search target is that the reliability difference between the redundant NFP and the optimal default NFP is the smallest, that is: Among them, is the reliability index of the default NFP, s in n is the reliability index from the source node to the farthest node in each stage of the default NFP when searching for the maximum reliable loop from stage 1 to stage n, and u n is the decision of the maximum reliable loop finally selected after searching all feasible loops in each stage.

6. The forwarding path method of the reliable virtual network as claimed in claim 4, characterized in that the reliability index of the topological subgraph is determined by the following formula: Wherein: is the reliability of the regional coloring marker number, is the reliability index of the red path, is the reliability index of the blue path.

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