Follow best practices for physical switches, switch connectivity, setup of VLANs and subnets, and access port settings.

Top of Rack Physical Switches

When configuring top of rack (ToR) switches, consider the following best practices.

  • Configure redundant physical switches to enhance availability.

  • Configure switch ports that connect to ESXi hosts manually as trunk ports. Virtual switches are passive devices and do not support trunking protocols, such as Dynamic Trunking Protocol (DTP).

  • Modify the Spanning Tree Protocol (STP) on any port that is connected to an ESXi NIC to reduce the time it takes to transition ports over to the forwarding state, for example, using the Trunk PortFast feature on a Cisco physical switch.

  • Provide DHCP or DHCP Helper capabilities on all VLANs that are used by the management and VXLAN VMkernel ports. This setup simplifies the configuration by using DHCP to assign IP address based on the IP subnet in use.

  • Configure jumbo frames on all switch ports, inter-switch link (ISL) and switched virtual interfaces (SVIs).

Top of Rack Connectivity and Network Settings

Each ESXi host is connected redundantly to the SDDC network fabric ToR switches by using two 10 GbE ports. Configure the ToR switches to provide all necessary VLANs via an 802.1Q trunk. These redundant connections use features of vSphere Distributed Switch and NSX for vSphere to guarantee no physical interface is overrun and redundant paths are used as long as they are available.

This Validated Design does not use hardware-based link aggregation. However, it is a valid design option and is supported by VMware. If you use hardware-based link aggregation, check vendor firmware versions and VMware product documentation to verify support requirements. See VMware Cloud Foundation documentation for a VMware validated and supported design using hardware-based link aggregation.

Figure 1. Host-to-ToR Connection


In this Validated Design, each host is connected to a pair of ToR switch using a 10-GbE connection.

VLANs and Subnets

Each ESXi host uses VLANs and corresponding subnets. 

Follow these guidelines:

  • Use only /24 subnets to reduce confusion and mistakes when dealing with IPv4 subnetting.

  • Use the IP address .253 as the (floating) interface with .251 and .252 for Virtual Router Redundancy Protocol (VRPP) or Hot Standby Routing Protocol (HSRP).

  • Use the RFC1918 IPv4 address space for these subnets and allocate one octet by region and another octet by function. For example, the mapping 172.regionid.function.0/24 results in the following sample subnets.

Note:

The following VLANs and IP ranges are samples. Your actual implementation depends on your environment.

Access Port Network Settings

Configure additional network settings on the access ports that connect the ToR switches to the corresponding servers.

Spanning Tree Protocol (STP)

Although this design does not use the STP, switches usually come with STP configured by default. Designate the access ports as trunk PortFast.

Trunking

Configure the VLANs as members of a 802.1Q trunk with the management VLAN acting as the native VLAN.

MTU

Set MTU for all VLANS and SVIs (Management, vMotion, VXLAN and Storage) to the value for jumbo frames for consistency purposes.

DHCP helper

Configure the VIF of the Management and VXLAN subnet as a DHCP proxy.

Multicast

Configure IGMP snooping on the ToR switches and include an IGMP querier on each VXLAN VLAN.