In an environment with multiple availability zones, Layer 2 networks must be stretched between the availability zones by the physical infrastructure.

Layer 3 gateways are in the VxBlock 1000 Cisco Nexus 9000 Switches and are highly available between availability zones.

Note: Static IP pools are not available for w-host-overlay. In a Multi AZ deployment, DHCP must be used.

The following table shows how the VLANs must be physically stretched between availability zones:

Table 2.      Stretched VLANs

The following table shows the VLANs that are created in each availability zone. The VLANs use the same VLAN numbers but are in different subnets of each availability zone.

Table 3.      VLANs in each availability zone

Stretched VLAN SVIs have different priorities on the ToR Cisco Nexus 9000 Switches to route traffic to the AZ1 ToR switch. The NSX Tier 0 peers with ToR Cisco Nexus 9000 Switches in AZs 1 and 2 by using the w-edge-uplink01 and w-edge-uplink02 stretched VLANs. NSX BGP local preference and route maps are applied to AZ 2 to ensure inbound and outbound traffic occurs through AZ1, unless it is down. Each AZ ToR Cisco Nexus 9000 Switch pair requires a unique BGP autonomous system ID. Each AZ ToR Cisco Nexus 9000 Switch pair must be in a different VPC domain. Expansion of a cluster requires that all the hosts have a shared datastore before creating the initial cluster or VI workload domain.

Note: When BGP is not used from the VxBlock 1000 to the customer core, configure the routing protocol at the customer core to use AZ 1 over AZ 2.

In the following figure, the NSX edge VMs are peered with the ToR Cisco Nexus 9000 Switches in each availability zone. HSRP on the ToR switches and route maps in the Tier 0 gateway cause the inbound and outbound traffic to use the switches in AZ 1.

Figure 11.    NSX and customer network routing configuration

The following table lists the workload domain VLANs for AZ-1 and AZ-2:

Table 4.      Workload domain VLANs

The following list details the route maps for AZ-2, which apply to the AZ-2 neighbors:

• Rm-in-az2 (in filter)

• Default route: Local preference 80
• Any: Local preference 90

• Rm-out-az2 (out filter)

• Any: AS path prepend 65004
• Any: Local preference 100