Digital Twin

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The digital twin is a digital replica of the live network, automatically built and continuously updated from the current network state. It reflects relevant topology, configuration, and operational information and can be used to simulate planned network changes before they are applied to the production network. This enables safer planning, impact assessment, and pre-deployment verification by allowing operators to evaluate expected behavior and identify potential issues without affecting live traffic.

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In this test, we simulated multiple scenarios using the digital twin and then verified their correctness by implementing the changes in the physical topology.

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**Topology Discovery and Model Building**

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The digital twin imported the full topology from the live network. The generated model contained all nodes, L3 links, IGP attributes, and TE parameters. Link-level attributes such as IGP cost and administrative state were captured in the model. We performed two independent runs with different controllers, and both produced consistent topology representations with identical node and link counts.

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We executed two test runs for this scenario as follows:

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* Cisco Crosswork Automation built topology for:

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Arista 7280R3, Cisco 8201-24H8FH, Ciena 5164, HPE MX204, Keysight IxNetwork and ZTE ZXR10 M6000-4SE .

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* ZTE ZENIC ONE R22 built topology for:

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Keysight IxNetwork, ZTE ZXR10 M6000-4SE

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**Planning Node and Link Addition**

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We introduced additional nodes and L3 links directly into the Digital Twin. The new elements were visible in the topology graph and resource inventory. The planning view incorporated the added links into routing calculations. When the same links and nodes were later deployed in the live network, routing behavior matched the simulated outcome.

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We executed one test run for this scenario as follows:

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* Cisco Crosswork Automation, Arista 7280R3, Cisco 8201-24H8FH, Keysight IxNetwork, HPE MX204, ZTE ZXR10 M6000-4SE.

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[[~[~[Figure 59: Digital Twin View for Links Planning~>~>image:483715328391708673_SDN-32-1-v1.png~|~|alt="Figure 59"~]~]>>attach:483715328391708673_SDN-32-1-v1.png||target="_blank"]]

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**Link Failure Simulation**

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We simulated a link failure within the Digital Twin. The failed link was marked unavailable and excluded from routing calculations. The controller recomputed alternate paths using the remaining topology and updated the Digital Twin view accordingly. The failure was then reproduced in the live network, and the observed routing behavior corresponded to the predicted simulation results.

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* Participants: Cisco Crosswork Automation, Arista 7280R3, Cisco 8201-24H8FH, HPE MX204, ZTE ZXR10 M6000-4SE.

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**IGP Metric Change Simulation**

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We simulated a change to an IGP metric on a link within the Digital Twin. The controller detected the topology update, recomputed candidate paths based on the new metric values, and reflected the updated view in the Digital Twin. The same metric change was then applied in the live network, and the routing behavior matched the predicted simulation results.

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* Participants: Cisco Crosswork Automation, Arista 7280R3, Cisco 8201-24H8FH, HPE MX204, ZTE ZXR10 M6000-4SE.

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