D[Label: 'Host,physical,logical1'] --> |Label: 'physical'| B
D[Node 4] --> |physical| B
B --> |Label: 'physical'| C[Label: 'Host,physical,logical1']
B --> |physical| C[Node 3]
B --> |Label: 'physical'| E[Label: 'Host,physical,logical1']
B --> |physical| E[Node 5]
A --> |Label: 'logical1'| B
A --> |logical1| B
B --> |Label: 'logical1'| C
B --> |logical1| C
C --> |Label: 'logical1'| D
C --> |logical1| D
D --> |Label: 'logical1'| E
D --> |logical1| E
E --> |Label: 'logical1'| A
E --> |logical1| A
end
```
```
The basic idea is to assign the different network elements to a specific Principal Network Domain (PND).
The basic idea is to assign the different network elements to a specific
The different topologies are represented by a neo4j relationship between the network elements that are
Principal Network Domain (PND). The different topologies are represented by a
stored as neo4j nodes. However, with this current variant it is not possible, as required in
neo4j relationship between the network elements that are stored as neo4j nodes.
However, with this current variant it is not possible, as required in
[Topology Inventory](#topology-inventory), to represent topologies that are hierarchically
[Topology Inventory](#topology-inventory), to represent topologies that are hierarchically
interdependent, since neo4j does not allow relations to be stored as properties (as described [here](https://neo4j.com/docs/cypher-manual/current/syntax/values/#structural-types)
interdependent, since neo4j does not allow relations to be stored as properties
(as described [here](https://neo4j.com/docs/cypher-manual/current/syntax/values/#structural-types)).
For the reason mentioned above, a more complex idea for persistence is available for the further development, which hopefully allows us to persist and map network elements, PNDs and topologies with all their hirarchical dependencies.
Furthermore, multiple links between the same nodes which belong to the same
topology are difficult to represent, since this model only provides a single
link between nodes of a certain topology.
The following figure tries to visualize this idea. The main difference is, that for the different topologies separate nodes are created, to which so-called links belong. The links themselves form a connection between the respective network elements. A link can have several layer protocols, like OTUCN, ODUCN etc.
For the reason mentioned above, a more complex idea for persistence is available
for the further development, which hopefully allows us to persist and map
network elements, PNDs and topologies with all their hirarchical dependencies.
The following figure tries to visualize this idea.
```mermaid
```mermaid
graph TD
graph TD
subgraph "dependencies of topologies"
subgraph "dependencies of topologies"
logical1 -->|related_to| physical
logical1 -->|related_to| physical
logical5 -->|related_to| physical
logical5 -->|related_to| physical
logical3 -->|related_to| logical1
logical3 -->|related_to| logical1
end
end
subgraph "every node belongs to a specific PND"
subgraph "every node belongs to a specific PND"
Node1 -->|belongs_to| PND
Node1 -->|belongs_to| PND
Node2 -->|belongs_to| PND
Node2 -->|belongs_to| PND
Node3 -->|belongs_to| PND
Node3 -->|belongs_to| PND
Node4 -->|belongs_to| PND
Node4 -->|belongs_to| PND
Node5 -->|belongs_to| PND
Node5 -->|belongs_to| PND
end
end
subgraph "relationship between nodes (nodes can be linked by 0...n links)"
subgraph "relationship between nodes (nodes can be linked by 0...n links)"
lp2[link_physical]
lp2[link_physical]
lp3[link_physical]
lp3[link_physical]
lp4[link_physical]
lp4[link_physical]
lp5[link_logical1]
lp5[link_logical1]
lp2 --> |connects| Node4
lp2 --> |connects| Node4
lp2 --> |connects| Node2
lp2 --> |connects| Node2
lp3 --> |connects| Node2
lp3 --> |connects| Node2
lp3 --> |connects| Node3
lp3 --> |connects| Node3
lp4 --> |connects| Node2
lp4 --> |connects| Node2
lp4 --> |connects| Node5
lp4 --> |connects| Node5
lp5 --> |connects| Node1
lp5 --> |connects| Node1
lp5 --> |connects| Node2
lp5 --> |connects| Node2
end
end
subgraph "links are part of a topology"
subgraph "links are part of a topology"
lp1[link_physical]
lp1[link_physical]
lp1 --> |connects| Node1
lp1 --> |connects| Node1
lp1 --> |connects| Node2
lp1 --> |connects| Node2
lp1 --> |part_of| physical
lp1 --> |part_of| physical
end
end
subgraph "links can contain 1...n layers"
subgraph "links can contain 1...n layers"
lp2 --> |contains| ODUH
lp2 --> |contains| ODUH
lp2 --> |contains| OTUCN
lp2 --> |contains| OTUCN
lp2 --> |contains| ODUCN
lp2 --> |contains| ODUCN
end
end
```
```
The basic structure explained in the upper part remains the same.
However, the relations, which previously served as links between the respective
nodes, now become **separate nodes**. These nodes now act as links between the
respective network elements and are part of a network topology (which itself
is represented as a separate node in the graph). By this change, network
topologies can now be interdependent. Furthermore, as can be seen in the figure
above, you can add additional nodes to the link nodes by using this scheme.
So a physical link between two nodes could e.g. **contain** several cables.
All other information can be stored in the properties of the respective nodes/edges.
The above idea is not yet approved and there are still open questions.
The above idea is not yet approved and there are still open questions.
- Is there a better solution for the assumption that there are several different physical connections between the same nodes than separate link nodes between them?
- Is there a better solution for the assumption that there are several different physical connections between the same nodes than separate link nodes between them?
- Can topologies run over different PNDs -> membership to different PNDs?
- Can topologies run over different PNDs -> membership to different PNDs?
- Where can we benefit from using different layers? (e.g. possible saving of unnecessary relations between nodes)
- Where can we benefit from using different layers? (e.g. possible saving of unnecessary relations between nodes)
- Do the sdn controllers provide us with the necessary information to map the topologies in this way?
