The network topology of the HCI stretched cluster is as follows.

Networking Description:

• Machine Room 1 and machine Room 2

Machine room 1 and machine room 2 form an HCI cluster. Under the condition of ensuring the interconnection of the management network, VXLAN network, and storage network of the two machine rooms, configure corresponding redundancy strategies for the management network, VXLAN network, and storage network in the machine room. Stack the three networks with two switches, and configure corresponding network aggregation on the HCI cluster. The recommendations are as follows:

Management network: Each node is aggregated with 2 * GE network interfaces and stacked with two separate management network switches.

VXLAN network: Each node is aggregated with 2 * GE network interfaces and stacked with two separate VXLAN network switches.

Storage network: Each node is aggregated with 2 * 10GE network interfaces and stacked with 2 separate storage network switches. Stretched clusters do not support storage area networks using RDMA.

The two machine rooms can set their own Edge. It is also recommended that the edge network adopt 2 * GE network interfaces for aggregation to provide services to the external network. If the conditions allow, providing the individual edge to the two machine rooms is suggested. If the conditions do not allow it, set the edge in the main service's machine room.

• Machine room network

Machine room 1 and machine room 2 are directly connected through the second layer of the network. It is recommended to use a 10 Gigabit bare optical fiber network for aggregation, and the network latency in the machine room should be less than or equal to 1 ms. The switches of the two machine rooms are stacked, and three different VLANs are divided on the stacked switches to carry the relevant data of the management network: the VXLAN network and the storage network of the two machine rooms.

• Witness Node

The witness node is important in the stretched cluster. It is different from the HCI system. To configure the witness node, you need to install the operating system of the witness node separately or purchase a separate aServer of the witness node. The regular communication between the witness node and the cluster shows whether the data copies in different computer rooms are abnormal and can be found in time. For the abnormal computer room, under the charge of the witness node, the business can continue to provide services in the computer room with normal data copies. The witness node can be deployed in the node room between machine room 1 and machine room 2 to carry services, or in a third-party site, provided that the witness node needs to be able to communicate with the HCI cluster IP. The link delay between the witness node and the cluster shall not be less than 5ms, and the recommended bandwidth is 100m.