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Dell VxRail Network Planning Guide

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Prepare for LAG of VxRail networks

LAG for specific VxRail networks is supported with VxRail 7.0.130 and later.

NIC teaming in VxRail is the foundation to support LAG. LAG is the bundling of two physical network links to form a single logical channel. LAG allows ports on a VxRail node to peer with a matching pair of ports on the ToR switches. This peering supports load-balancing and optimizes network traffic distribution across the physical ports. VxRail networks with heavy resource requirements, such as VMware vSAN and VMware vSphere vMotion, benefit most from network traffic optimization.

Figure 1. Dependent LAG features. Dependent LAG features
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. VMware VDS port group is assigned a teaming and failover policy to enable better distribution across the two uplinks. True load balancing is not achievable without LAG. Enabling LAG allows the VxRail network to use the bandwidth of both uplinks. The traffic flow is coordinated based on the load-balancing hash algorithm that is configured on the VMware VDS and the ToR switches.

Be familiar with the following functionality dependencies if considering LAG with VxRail:
  • The switches that are targeted for the VxRail cluster must support LACP. LACP is the protocol that dynamically forms a peering relationship between ports on two separate switches. Dynamic LAG requires an LACP policy to be configured on the VMware VDS to enable this peering to be established with the adjacent ToR switches.
  • LACP is considered the best practice for LAG because it offers support for more load-balancing hashing algorithms and superior management capabilities.
  • For network topologies using two or more switches to support VxRail networking, the switch operating system must support:
    • Multi-Chassis Link Aggregation (MLAG) to allow LAG to span the two switches.
    • Virtual Link Trunking to enable the networks in a port channel to pass through the two switches at one end of a LAG group.
  • LAG is not supported if the Ethernet adapters supporting the VMware vSAN network are enabled for RDMA over Converged Ethernet (RoCE).

LAG is not supported on the VxRail management networks earlier than VxRail 7.0.450. The following minimum VxRail versions must be used when using LAG with VxRail:

  • Customer-managed VMware VDS: VxRail 7.0.130
  • VxRail-managed VMware VDS: VxRail 7.0.450
  • All VxRail networks: VxRail 7.0.450
Follow these VxRail network guidelines to enable LAG:
  • VxRail supports a single LAG group per cluster.
  • Two Ethernet ports can only be configured into a LAG group.
  • The VxRail cluster must be running VxRail 7.0.450 or 8.0.x or later cluster to enable LAG with two, four, six, or eight ports.
  • The Ethernet ports that are selected for LAG can be all NDC/OCP-based, all PCIe-based, or a mixture of NDC/OCP and PCIe Ethernet ports.
  • All ports that are configured for LAG must be running at the same speed.
Figure 2. Sample LAG options for VxRail networking. Sample LAG options for VxRail networking
Sample link aggregation options for VxRail networking
Follow these guidelines to enable LAG on a customer-managed VMware VDS:
  • You must supply a compatible VMware vCenter Server instance to serve as the target for the VxRail cluster.
  • You must supply a compatible and preconfigured VMware VDS to support the VxRail networking requirements.
  • Preconfigure the LACP policy to support LAG and load-balancing on the VMware VDS.
Follow these guidelines to enable LAG on a VxRail-managed VMware VDS:
  • Switch ports configured as port channels shut down by default if they do not form a pairing with another pair of ports on another switch.
  • VxRail requires those switch ports to remain open and active during the VxRail initial implementation process.

The switches that are targeted for the VxRail cluster must support enabling the individual ports in the port channel to stay open and active if they do not form a LAG partnership with other switch port pairs within the configured timeout setting. (On Dell-branded switches running OS10, this is known as the LACP individual feature.) On Cisco-branded switches, the feature is LACP suspend-individual. This feature should be disabled on the switch ports in an EtherChannel to prevent the ports from shutting down. Check the documentation for switches from other vendors for the proper feature description.

Switch support for LAG

The selection of load-balancing hashing algorithms and the formation of LAG on the physical switches depends on the switch vendor and operating system. These features are 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.

Support for multichassis LAG

To deploy a pair of switches to support the VxRail cluster, and enable load-balancing across both switches, the switches must support the ability for the networks in a LAG group to logically flow across both switches. The switch operating system must support the multi-chassis LAG feature, such as Cisco Virtual Port Channel. See the guides provided by your switch vendor for the steps to complete this task.

Support for LACP individual or similar feature

If you plan to deploy VxRail with a VxRail-managed VMware VDS, then the switches must support the LACP individual or compatible feature. By default, switch ports that are configured for LAG are set to an inactive state until such time it has exchanged LACP PDUs with a LAG on another adjacent switch. When these PDUs are exchanged, the two LAGs can then sync into a partnership, and the sets of ports become active.

Figure 3. Enable connectivity for VxRail initial implementation with LAG. Enable connectivity for VxRail initial implementation with LAG
Enabling connectivity for VxRail initial implementation with LAG

An individual VxRail node connects to the adjacent ToR with a standard virtual switch at power-on, and virtual switches do not support LAG. The LACP policy that is configured by VxRail on the VxRail-managed VMware VDS during the initial implementation process cannot exchange LACP DPUs at the power-on stage. This peering relationship does not occur until VxRail begins the virtual network formation stage later in the initial implementation process. Using this feature enables a switch port that is configured for LAG to be set to an active state to enable VxRail connectivity and allow initial implementation to proceed.

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