Link aggregation for specific VxRail networks is supported starting with VxRail version 7.0.130. NIC teaming in VxRail is the foundation for supporting link aggregation, which is the bundling of two physical network links to form a single logical channel. Link aggregation allows ports on a VxRail node to peer with a matching pair of ports on the top-of-rack switches to support load-balancing and optimize network traffic distribution across the physical ports. VxRail networks with heavy resource requirements, such as vSAN and potentially vMotion, benefit most from network traffic optimization.

Figure 45.    Overview of LAG peering relationship between VxRail and the adjacent switches

Each VxRail network is assigned two uplinks by default during the initial implementation operation. One uplink is designated as ‘active’, and the other uplink as ‘standby’. Under this model, resource-intensive networks are limited to the bandwidth of a single uplink. Enabling link aggregation allows the VxRail network to use the bandwidth of both uplinks, with the traffic flow coordinated based on the load-balancing hash algorithm.

The following guidelines must be followed when using NIC teaming and link aggregation with VxRail:

• The VxRail cluster must be running version 7.0.130 to enable NIC teaming and support link aggregation. 
• Link aggregation is not supported on the VxRail management networks. These networks have low-bandwidth requirements, and load-balancing would offer minimal benefit.
• Link aggregation is not supported if the Ethernet adapters supporting the vSAN network are enabled for RDMA over Converged Ethernet (RoCE). 
• The virtual-distributed switch that is integrated into the VxRail cluster supports LACP. 

• If the switches that support the VxRail cluster support LACP, dynamic link aggregation can be configured on the VxRail networks.
• If LACP is not supported on the switches, static link aggregation can be configured on the VxRail networks.
• LACP is more favorable because it offers support for more load-balancing hashing algorithms and better management capabilities.

• To enable NIC teaming and link aggregation during the VxRail initial build process:

• You must supply a compatible vCenter instance to serve as the target for the VxRail cluster.
• You must supply a compatible and preconfigured virtual-distributed switch to support the VxRail networking requirements.
• Link aggregation and load-balancing are preconfigured on the virtual-distributed switch.

• NIC teaming and link aggregation can be configured on the VxRail-supplied virtual-distributed switch after the VxRail cluster build is complete.

• If the target version for your VxRail cluster being delivered is earlier than 7.0.130, the cluster can be upgraded after the build operation is complete.
• See Enabling link aggregation for load-balancing for details on configuring link aggregation after VxRail initial implementation.

• Four, six, or eight Ethernet ports per node must be reserved for VxRail networking.

• The six-port and eight-port options require VxRail version 7.0.400 or later.
• Can be a mixture of NDC/OCP and PCIe Ethernet ports
• All NDC/OCP-based or all PCIe-based Ethernet ports are also supported.
• Two ports are reserved for the VxRail management networks. NIC teaming is not supported on this port pair.
• Two ports are reserved for the VxRail non-management networks (vSAN/vMotion). NIC teaming is supported on this port pair.
• All ports configured for link aggregation must be running at the same speed.

Support for LACP, the selection of load-balancing hashing algorithms and the formation of link aggregation on the physical switches depends on the switch vendor and operating system. These features are usually branded by the vendor, using names such as ‘Ether-Channel’, ‘Ethernet trunk’, or ‘Multi-Link Trunking’. Consult your switch vendor to verify that the switch models that are planned for the VxRail cluster supports this feature.

Verify support for multi-chassis link aggregation

If you plan to deploy a pair of switches to support the VxRail cluster, and you want to enable load-balancing across both switches, you must configure multi-chassis link aggregation. This feature is usually branded by the switch vendor, such as Cisco’s Virtual Port Channel or Dell’s VLT Port Channel. See the guides provided by your switch vendor for the steps to complete this task.

Identify switch ports to be configured for link aggregation

Enabling load-balancing for the non-management VxRail networks requires peering the pair of ports on each VxRail node with a pair of ports on the top-of-rack switches.

  Figure 46. Plugging into equivalent switch ports for link aggregation

If you are enabling link aggregation across a pair of switches, and you have matching open ports on both switches, the best practice is to plug the cables into equivalent port numbers on both switches. We recommend creating a table to map each VxRail node port to a corresponding switch port. Then, identify which ports on each VxRail will be enabled for link aggregation.

For example, if you want to deploy a VxRail cluster with four nodes, and reserve and use two ports on the NDC/OCP and two ports on a PCIe adapter card for the VxRail cluster, and use the first eight ports on a pair of top-of-rack switches for connecting the cables, you could use the resulting table to identify the switch ports to be configured for link aggregation.  

Figure 47. Sample port-mapping table

Assuming that you are using the second port on the NDC/OCP and PCIe adapter card for the non-management VxRail networks, you can identify the switch port pairs, as shown in the columns shaded green, to be configured for link aggregation.

Dell Technologies recommends creating a table mapping the VxRail ports to the switch ports and part of the planning and design phase.