CN116319537A

CN116319537A - Routing availability calculation method based on node sequence

Info

Publication number: CN116319537A
Application number: CN202310344282.6A
Authority: CN
Inventors: 耿海军; 胡睿乾
Original assignee: Shanxi University
Current assignee: Shanxi University
Priority date: 2023-03-30
Filing date: 2023-03-30
Publication date: 2023-06-23
Anticipated expiration: 2043-03-30
Also published as: CN116319537B

Abstract

The invention relates to a routing availability calculation method based on a node sequence. Firstly, defining a network as a topological graph, wherein routers are represented as nodes in the topology, links connected between the routers are defined as edges, and the edges are represented by G= (V, E, weight); selecting one node in the node set V as an initial node and assigning the initial node to d, wherein the initial node is a destination node, and the calculation steps are as follows: step 1: initializing a backup next-hop node set; initializing an output list S and an alternative node list T; step 2: calculating a shortest path tree taking a destination node d as a root; step 3: calculating V-S, and judging whether the V-S is empty or not; step 4: for the node w epsilon S, V epsilon V-S, if (w, V) epsilon spt (d), adding the node V into the alternative node list T; step 5: for node u e T, calculating d (u, S); step 6: according to the node selection rule, selecting a node x meeting the condition; step 7: calculating the next hop node of the node x according to the backup next hop calculation rule; step 8: it is determined whether the node set v=s is established.

Description

Routing availability calculation method based on node sequence

Technical Field

The invention belongs to the technical field of Internet, and particularly relates to a routing availability calculation method based on a node sequence.

Background

With the continuous development of open computer networks, the transmission of data packets in the networks can run between networks with different network protocols, and compared with the traditional internet, the open network architecture can truly realize the reciprocal sharing of internet resources and the distributed processing goal of data. However, once the internet encounters network faults, such as faults caused by physical factors of earthquake, tsunami and the like, and system faults caused by certain configuration errors of internet nodes, the faults affect normal operation of the internet, and thus temporary interruption of the network is caused. In order to ensure that the goal of high reliability is achieved in the process of transmitting data over the internet, it is necessary to devise a scheme to improve the availability of routes in the network.

In this regard, many routing protocols for packet transmission, such as the open shortest path first protocol (Open Shortest Path First, OSPF), have been designed, which have the disadvantages of complex configuration, low security, and failure to achieve load balancing. While routing protocols can ensure the transmission of data packets to some extent, they do not ensure that the network can recover completely in the event of a failure, and recovery times are sometimes on the order of seconds, which is intolerable in networks. Based on failure recovery strategies of IP networks, there has been some research in the academy world, such as multiprotocol label switching (Multi-Protocol Label Switching, MPLS) fast reroute, which is to redistribute traffic affected by a failure onto a backup path, the implementation of the MPLS protocol depending on the label switching router (Label Switching Router, LSR). Its disadvantages are also apparent that the protocol can only operate in MPLS-enabled networks and that the deployment overhead is relatively large. For another example, an Equal-Cost Multi-Path Routing (ECMP) mechanism, the ECMP distributes packets over several outbound links between the start and end points, and as soon as one router detects that one of the outbound links is not available, it forwards the packet onto the remaining links. Its advantage is simplicity, but its disadvantage is less contribution to route availability.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art and provides a routing availability calculation method based on a node sequence.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a route availability calculation method based on node sequence firstly defines a network as a topological graph, routers are represented as nodes in the topology, links connected between the routers are defined as edges, and G= (V, E, weight) is used for representing the topological graph, wherein G represents the topological graph, V is a node set of the topological graph G, E is an edge set of the topological graph G, and Weight represents the cost of the edges in the topological graph G; selecting one node in the node set V as an initial node and assigning the initial node to d, wherein the initial node is a destination node, and the calculation steps are as follows:

step 1: for node k e V in topology, initialize

bn (k, d) represents the next hop node set from node k to node d; initializing an output list s= { d }, an alternative node list +.>

Step 2: calculating a shortest path tree spt (d) taking a destination node d as a root, wherein spt (d) represents the shortest path tree taking the d node as the destination node;

step 3: computing node sets in V-S, if

The algorithm ends; otherwise, executing the step 4;

step 4: for nodes w e S, V e V-S in the topology, if (w, V) e spt (d), adding node V into an alternative node list T, namely T=T { V };

step 5: for node u e T in the topology, calculating d (u, S), where d (u, S) represents the number of edges that node u connects to list S;

step 6: selecting a node x meeting the condition from the topology according to the node selection rule, and adding the node x into the list S;

step 7: calculating the next hop node of the node x obtained in the step 6 according to the backup next hop calculation rule;

step 8: judging whether the node set V=S is true, and ending the algorithm if V=S; otherwise, step 3 is executed.

Further, the node selection rule in the step 6 specifically includes:

step 6.1: selecting a node with two edges from the alternative node list T and the output list S, adding the node into the output list S if the node is satisfied, executing the step 6.2 if a plurality of nodes are satisfied, and executing the step 6.3 if the node is not satisfied;

step 6.2: if a plurality of nodes meet the condition in the step 6.1, selecting the node with the smallest ID (m) to be added into the output list S, and continuing to execute the step 7, wherein the ID (m) represents the name of the node m in the topology, namely the node number of the node m;

step 6.3: if no node meets the condition in the step 6.1, selecting the node with the most edge connected with the output list S in the alternative node list T and adding the node into the output list S; if a plurality of nodes meet the conditions, executing the step 6.4, otherwise, executing the step 7;

step 6.4: if a plurality of nodes meet the condition in the step 6.3, the node with the smallest ID (m) is selected to be added to the output list S, and the step 7 is continuously executed.

Further, the backup next-hop calculation rule in step 7 specifically includes:

for node x e S, y e N (x), N (x) representing the adjacent node of node x; if y is added to the output list S before x, y may be the next-hop node from node x to node d, that is bn (x, d) =bn (x, d)/(y).

The beneficial effects of the invention are as follows:

the invention can realize the route forwarding work by defining the node sequence, when the fault occurs, the data packet can be forwarded to the backup next-hop node, and the problem that a route loop is possibly generated in the forwarding process can be avoided. Therefore, compared with the background art, the invention has the following advantages: the output list S is a main sequence for forwarding the data packet, and the data packet is forwarded from large to small according to the node mark when the data packet is forwarded. The backup next-hop node is pre-calculated, so that the convergence time of the route in the network can be greatly saved, and the network can be quickly restored. In addition, through the use of the invention, the number of the backup next-hop nodes of each node can be greatly increased, the route recovery time is saved, and the fault protection rate in the network is improved.

The method has the advantages of low cost, simple deployment and easy realization, and can be operated only by formulating special node selection rules and node sequence relations. The invention can provide an effective solution for improving the availability of the route in the network and maintaining the stability of the network.

Drawings

FIG. 1 is a schematic flow chart of the present invention;

FIG. 2 is a schematic diagram of the network topology of the present invention;

fig. 3 is a schematic diagram of a shortest path tree rooted at node 4 in the network topology of the present invention.

Detailed Description

The invention is described in detail below with reference to the drawings and examples.

As shown in fig. 1, in this embodiment, a method for calculating route availability based on a node sequence is defined as a topology graph, routers are represented as nodes in the topology graph, links connected between the routers are defined as edges, and g= (V, E, weight) is used to represent the topology graph, V is a node set of the topology graph G, E is an edge set of the topology graph G, and Weight is used to represent costs of the edges in the topology graph G; selecting one node in the node set V as an initial node and assigning the initial node to d, wherein the initial node is a destination node, and the calculation steps are as follows:

step 1: for node k e V in topology, initialize

step 3: computing node sets in V-S, if

The algorithm ends; otherwise, executing the step 4;

Further, the node selection rule in the step 6 specifically includes:

Further, the backup next-hop calculation rule in step 7 specifically includes:

Specific examples are:

as shown in fig. 3, the node 4 is selected as a destination node of the algorithm, and the calculation steps are as follows:

step 1: for node 0, node 1, node 2, node 3, node 4, initialization in the topology

Initializing an output list s= {4}, an alternative node list +.>

Step 2: calculating a shortest path tree spt (4) taking a destination node 4 as a root, namely spt (4) = { (0, 1), (4, 0), (4, 2), (0, 3) };

step 3: a set of V-S is calculated and,

executing the step 4;

step 4: for nodes 4 e S,0 e V-S,1 e V-S,2 e V-S,3 e V-S, where (4, 0), (4, 2) e spt (4), so add node 0, node 2 to the alternative node list T, i.e., T=T {0,2};

step 5: for node 0 e T,2 e T, get d (0,S) =d (2, s) =1;

step 6.1: the

nodes

0 and 2 in the alternative node list T do not meet the requirement that the output list S has two sides, and the step 6.3 is executed;

step 6.3: node 0 and node 2 are both edges, so that the node connected with the output list S most edge in the alternative node list T is selected;

step 6.4: since both node 0 and node 2 meet the condition in step 6.3, the node with the smallest select ID (m) is selected, node 0 meets the condition, and node 0 is selected for joining, i.e., s= {4,0}.

Step 7: for node 0 e S,4 e N (0), node 4 joins the list S earlier than node 0, then node 4 can be the next hop node from 0 to 4, i.e., bn (0, 4) =bn (0, 4)/(4) u {4};

step 8: judging that V is not equal to S, and executing the step 3;

step 3: a set of V-S is calculated and,

executing the step 4;

step 4: for nodes 0 e S,4 e S,1 e V-S,2 e V-S,3 e V-S, where (0, 1), (0, 3), (4, 2) e spt (4), node 1, node 2 and node 3 are added to the list of alternative nodes T, i.e., T = T {1,2,3};

step 5: for nodes 1 e T,2 e T,3 e T, d (2, s) =2, d (1, s) =d (3, s) =1;

step 6.1: the node 2 in the alternative node list T meets the condition that two edges exist between the node 2 and the output list S, and no other nodes meet the condition, so that the node 2 is added into the list S, namely S= {4,0,2}, and the step 7 is executed;

step 7: for the nodes 2 epsilon S,0 epsilon N (2), 4 epsilon N (2), and the

nodes

4 and 0 are added into the list S before the node 2, the

nodes

4 and 0 can be used as the next-hop nodes from 2 to 4, namely bn (2, 4) =bn (2, 4) {0,4};

step 8: judging that V is not equal to S, and executing the step 3;

step 3: a set of V-S is calculated and,

executing the step 4;

step 4: for nodes 0 e S,2 e S,4 e S,1 e V-S,3 e V-S, where (0, 1), (0, 3) e spt (4), node 1 and node 3 are added to the alternative node list T, i.e., T=T {1,3};

step 5: for node 1 e T,3 e T, d (1, s) =1, d (3, s) =2;

step 6.1: the node 3 in the alternative node list T meets the condition that two edges exist between the node 3 and the output list S, and no other nodes meet the condition, so that the node 3 is added into the list S, namely S= {4,0,2,3}, and the step 7 is executed;

step 7: for the nodes 3 epsilon S,0 epsilon N (3), 2 epsilon N (3), and the

nodes

2 and 0 are added into the list S before the node 3, the

nodes

2 and 0 can be used as the next-hop nodes from 3 to 4, namely bn (3, 4) =bn (3, 4) {0,2};

step 8: judging that V is not equal to S, and executing the step 3;

step 3: a set of V-S is calculated and,

executing the step 4;

step 4: for nodes 0 e S,2 e S,3 e S,4 e S,1 e V-S, where (0, 1) e spt (4), node 1 is added to the alternative node list T, i.e., T=TU {1};

step 5: for node 1 e T, d (1, s) =2;

step 6.1: in the alternative node list T, the node 1 meets the condition that two edges exist between the node 1 and the output list S, and no other nodes meet the condition, so that the node 1 is added into the list S, namely S= {4,0,2,3,1}, and the step 7 is executed;

step 7: for the nodes 1 epsilon S,0 epsilon N (1), 3 epsilon N (1), and node 3 and node 0 are added into the list S before the node 1, then both the node 3 and the node 0 can be used as the next hop nodes from 1 to 4, namely bn (1, 4) =bn (1, 4) {0,3};

step 8: and judging that V=S, and ending the algorithm.

Claims

1. A route availability calculation method based on a node sequence is characterized by comprising the following steps: firstly, defining a network as a topological graph, wherein routers are represented as nodes in the topological graph, links connected between the routers are defined as edges, and the edges are represented by G= (V, E, weight), wherein G represents the topological graph, V is a node set of the topological graph G, E is an edge set of the topological graph G, and Weight represents the cost of the edges in the topological graph G; selecting one node in the node set V as an initial node and assigning the initial node to d, wherein the initial node is a destination node, and the calculation steps are as follows:

step 1: for node k e V in topology, initialize

step 3: computing node sets in V-S, if

The algorithm ends; otherwise, executing the step 4;

2. A method of computing route availability based on a sequence of nodes according to claim 1, wherein: the node selection rule in the step 6 specifically includes:

3. A method of computing route availability based on a sequence of nodes according to claim 1, wherein: the backup next-hop calculation rule in the step 7 specifically includes: