The universal segment ID pool specifies a range for use when building logical network segments. Cross-vCenter NSX deployments use a unique universal segment ID pool to ensure that the universal logical switches VXLAN network identifiers (VNIs) are consistent across all secondary NSX Managers.
The universal segment ID pool is defined once on the primary NSX Manager and then synchronized to the secondary NSX Managers. Note that the segment ID range must be unique across any NSX Manager that you plan use in a cross-vCenter NSX deployment. This example uses a high range to provide future scalability.
When determining the size of each segment ID pool, consider that the segment ID range controls the number of logical switches that can be created. Choose a small subset of the 16 million potential VNIs. Do not configure more than 10,000 VNIs in a single vCenter because vCenter limits the number of dvPortgroups to 10,000.
If VXLAN is in place in another NSX Data Center for vSphere deployment, consider which VNIs are already in use and avoid overlapping VNIs. Non-overlapping VNIs is automatically enforced within a single NSX Manager and vCenter environment. Local VNI ranges cannot be overlapping. However, it is important for you make sure that VNIs do not overlap in your separate NSX Data Center for vSphere deployments. Non-overlapping VNIs is useful for tracking purposes and helps to ensure that your deployments are ready for a cross-vCenter environment.
If any of your transport zones use multicast or hybrid replication mode, you must add a multicast address or a range of multicast addresses.
You must ensure that the multicast address or address range specified does not conflict with other multicast addresses assigned on any NSX Manager in the cross-vCenter NSX environment.
Having a range of multicast addresses spreads traffic across your network, prevents the overloading of a single multicast address, and better contains BUM replication.
Do not use 239.0.0.0/24 or 239.128.0.0/24 as the multicast address range, because these networks are used for local subnet control, meaning that the physical switches flood all traffic that uses these addresses. For more information about unusable multicast addresses, see https://tools.ietf.org/html/draft-ietf-mboned-ipv4-mcast-unusable-01.
- Make sure that the underlying physical switch is configured with an MTU larger than or equal to 1600.
- Make sure that the underlying physical switch is correctly configured with IGMP snooping and an IGMP querier in network segments that carry VTEP traffic.
- Make sure that the transport zone is configured with the recommended multicast address range. The recommended multicast address range starts at 239.0.1.0/24 and excludes 239.128.0.0/24.
You can configure a single segment ID range and a single multicast address or multicast address range from the vSphere Web Client . If you want to configure multiple segment ID ranges or multiple multicast address values, you can do this using the API. See the NSX API Guide for details.
