# Configuring InfiniBand Switches

In your HPC cluster, connect the Mellanox InfiniBand switches using the Fat-Tree topology. In the fat-tree topology, switches in layer 1 are connected through the switches in the upper layer, i.e., layer 2. And, all the compute nodes in the cluster, such as PowerEdge servers and PowerVault storage devices, are connected to switches in layer 1. With this topology in place, we ensure that a 1x1 communication path is established between the compute nodes. For more information on the fat-tree topology, see [Designing an HPC cluster with Mellanox infiniband-solutions](https://community.mellanox.com/s/article/designing-an-hpc-cluster-with-mellanox-infiniband-solutions).

Omnia uses the server-based Subnet Manager (SM). SM runs in a Kubernetes namespace on the control plane. To enable the SM, Omnia configures the required parameters in the `opensm.conf` file. Based on the requirement, the parameters can be edited.  

>>**Note**: Install the InfiniBand hardware drivers by running the below command:  
>> * `yum groupinstall "Infiniband Support" -y` (For Rocky)

## Setting up a new or factory reset switch

Before running `infiniband.yml`, ensure that HTTP and JSON Gateway are enabled on your switch. This can be verifed by running:

`show web` (To check if HTTP is enabled)

`show json-gw` (To check if JSON Gateway is enabled)

In case either service has been disabled, run:

`web http enable` (To enable the HTTP gateway)

`json-gw enable` (To enable the JSON gateway)



When connecting to a new or factory reset switch, the configuration wizard requests to execute an initial configuration:
* **(Recommended)** If the user enters 'no', they still have to provide the admin and monitor passwords. 
* If the user enters 'yes', they will also be prompted to enter the hostname for the switch, DHCP details, IPv6 details, etc.

>> **Note:** When initializing a factory reset switch, the user needs to ensure DHCP is enabled and an IPv6 address is not assigned. Omnia will assign an IP address to the Infiniband switch using DHCP with all other configurations.

## Configuring Mellanox InfiniBand Switches

Enter all relevant parameters for configuring your switches in the following files per the provided [Input Parameter Guides](../Input_Parameter_Guide/Control_Plane_Parameters).:
* base_vars.yml
* opensm.conf (optional)
* ib_vars.yml


### Run infiniband_template on the AWX UI.
1. Run `kubectl get svc -n awx`.
2. Copy the Cluster-IP address of the awx-ui. 
3. To retrieve the AWX UI password, run `kubectl get secret awx-admin-password -n awx -o jsonpath="{.data.password}" | base64 --decode`.
4. Open the default web browser on the control plane and enter `http://<IP>:8052`, where IP is the awx-ui IP address and 8052 is the awx-ui port number. Log in to the AWX UI using the username as `admin` and the retrieved password.  
5. Under __RESOURCES__ -> __Templates__, launch the **infiniband_template**.