docs(xo): document network bonding (#8874)

Network bonding was absent from the Xen Orchestra documentation. Information about this feature was previously only available in a blog article on XCP-ng.

This commit updates the XO doc so that it properly documents this feature, and remains the single source of truth in this topic. XO users won't have to dig through blog posts to find the relevant information, making the documentation more useful and trustworthy.

Signed-off-by: Thomas Moraine <[email protected]>

docs/docs/manage_infrastructure.md

@@ -701,6 +701,70 @@ To remove one host from a pool, you can go to the "Advanced" tab of the host pag
 - The host you want to remove must be a slave, not the master!
 :::
 
+### Network bonding
+
+#### Definition
+
+Network bonding, also known as link aggregation, involves combining two or more physical network interfaces into a single logical interface.
+
+The primary goals are to improve redundancy —so that a single cable or interface failure does not interrupt connectivity— and, depending on the bonding mode, to increase throughput by distributing traffic across multiple links.
+
+#### Supported bond types
+
+Xen Orchestra supports the following bond types:
+
+- **Active / Active (Balance-SLB)**  
+  - Does **not** require switch awareness (no LACP needed)
+  - Balances traffic across all bond members
+  - Automatically shifts traffic to remaining members if one link fails
+  - May have compatibility issues with some low-end switches
+  - Unlike LACP, Active/Active bonds can span ports on different switches
+
+- **Active / Backup**  
+  - Does **not** require switch awareness
+  - Uses one primary interface for traffic, switching to backup only upon link failure
+  - Unlike LACP, Active/Backup bonds can span ports on different switches
+
+- **LACP**  
+  - Requires the switch to support and be configured for LACP
+  - Offers rapid failover and can detect mid-span link failures even if the physical link stays up
+  - Balances traffic across all bond members during normal operations
+  - All participating ports must be on the same physical switch, or on switches that operate together as a single logical switch
+
+#### Creating a LACP bond
+
+1. Navigate to **New → Network** to open the **Create Network** page.  
+2. Choose the pool where you want the bond to be created.
+3. Enable the **Bonded network** toggle:
+    ![Bond creation interface](./assets/bond0.png)
+4. In the **Interface** dropdown, select two or more physical interfaces (PIFs) to include in the bond.  
+5. Provide a **name** and a **description** for the bond.
+6. Set the **Bond mode** to **LACP**.
+7. Leave the **MTU** field blank. This will work as-is in most cases.
+8. Click **Create network**.
+    XO will then create the bond on the host(s):
+    ![Newly-created bond](./assets/bond1.png)
+
+:::tip
+- If applied to a pool, the bond is created across all pool members, so make sure all your pool members are cabled and configured on the switch side for LACP!
+- If the host’s management interface resides on one of the selected interfaces, XO will **automatically migrate the management interface** on top of the new bond (e.g., if management was on `eth0` and the bond consists of `eth0` + `eth1`).
+:::
+
+#### Adding VLANs on top of bonds
+
+Once a bond (e.g., `bond0`) is created, you can build VLANs over it:
+
+1. Go again to **New → Network** screen.  
+2. Select the new bond interface (e.g., `bond0`) in the **Interface** dropdown.  
+3. Provide a **name**, **description**, and specify the **VLAN** ID (for instance, `20`):
+    ![Setting up a VLAN on top of a new network bond](./assets/bond2.png)
+4. Validate the VLAN network creation.\
+    This creates a virtual network on top of the bond, using the name and ID you've specified, available for VM attachment.
+
+:::tip
+This process is the same whether you're adding a VLAN on top of a LACP network bond, or a bond in another mode (such as Active/Active or Active/Backup).
+:::
+
 ## Storage Management
 
 ![](./assets/xo5storageadvanced.png)