NSX-T is a network virtualization platform that allows for the creation of virtual networks and switches, as well as the provisioning of network services such as load balancing and firewalls. It is used in cloud environments and data centers to provide a flexible and scalable network infrastructure.

Here are some key concepts and features of NSX-T:

1. Logical Routers (LRs): These are virtual switches that provide Layer 2 and Layer 3 connectivity between virtual machines (VMs) and the physical network. There are two types of LRs: T0 and T1. T0 LRs are used for north-south traffic, while T1 LRs are used for east-west traffic.

2. Distributed Router (DR): This is a component of NSX-T that provides routing between LRs. It is distributed across the transport nodes in the network, and it enables the creation of virtual networks and subnets.

3. Service Router (SR): This is a centralized router that is used to provide services such as load balancing and firewalling. It is deployed on edge nodes, which are physical or virtual machines that are located at the edges of the network.

4. Edge Nodes: These are physical or virtual machines that are used to host logical routers and service routers. They can be bare-metal servers or VMs, and they can be configured to support different networking protocols such as BGP and OSPF.

5. Equal Cost Multi-Pathing (ECMP): This is a feature of NSX-T that allows for the distribution of traffic across multiple paths in the network. It is useful for load balancing and improving network performance.

6. Bidirectional Forwarding Detection (BFD): This is a feature of NSX-T that enables the detection of bidirectional forwarding between two devices in the network. It is used to ensure that traffic is being sent in both directions between devices, and it can help to troubleshoot network issues.

7. Failure Domains: These are groups of edge nodes that are configured to fail together in case of a failure. By defining failure domains, you can ensure that your network remains available even in the event of a failure.

8. HA (High Availability): This is a feature of NSX-T that enables you to deploy multiple instances of logical routers and service routers across different nodes in the network. It ensures that your network remains available even in the event of a failure.

Some best practices for using NSX-T include:

1. Use logical routers to provide Layer 2 and Layer 3 connectivity between VMs and the physical network.

2. Use distributed routing to provide routing between logical routers.

3. Use service routers to provide services such as load balancing and firewalling.

4. Use edge nodes to host logical routers and service routers.

5. Configure failure domains to ensure that your network remains available even in the event of a failure.

6. Use ECMP to distribute traffic across multiple paths in the network.

7. Use BFD to detect bidirectional forwarding between devices in the network.

8. Use HA to ensure that your network remains available even in the event of a failure.

Some new features and enhancements in NSX-T 2.5 include:

1. Support for two failure domains per edge cluster, which allows you to define two different groups of edge nodes that can fail together.

2. Improved support for HA, which enables you to deploy multiple instances of logical routers and service routers across different nodes in the network.

3. Enhanced support for ECMP, which allows for more flexible and efficient traffic distribution.

4. Support for BFD, which enables the detection of bidirectional forwarding between devices in the network.

5. Improved support for load balancing and firewalling, which enables you to provide more sophisticated networking services.