NSX-T is definitely a game changer. Latest release (version 2.4) brings in a lot of new functionality getting to parity with its vSphere counterpart. Coming from an NSX-v background, I am interested in the main differentiators that NSX-T is bringing into the game.
1. Cross platform support and independence from vCenter Server.
The two come together since supporting multiple platforms required decoupling NSX Manager from vCenter Server. Besides supporting vSphere, NSX-T can also support non-ESX hypervisors such as KVM. I expect to see more coming in the near future. Lastly, NSX-T supports bare metal workloads and native public clouds (see integrating AWS EC2 instances - youtube video here )
I will add here the NSX-T container plugin (NCP) that provides integration with container orchestration platforms (Kubernetes) and container based platform as a service (OpenShift, Pivotal Cloud Foundry).
That's a big step from vSphere environments.
2. Encapsulation protocol
At the core of any network virtualization technology is an encapsulation protocol that allows to send L2 protocols over L3. NSX-v uses VXLAN. Geneve is the protocol used by NSX-T. At the time of writing, Generic Network Virtualization Encapsulation (Geneve) is still an IETF draft, although on the standards track. According to people much wiser than me and that were involved in the specification design for Geneve, what the new protocol brings on the table is bringing the best from other protocols such as VXLAN, NVGRE and STT.
One of the main advantages of Geneve is that is uses a variable length header which allows to include as many options as necessary without being limited to the 24 bit header of VXLAN and NVGRE or using all the time a 64 bit STT style header.
3. N-VDS
NSX-T virtual distributed switches are called N-VDS and they are independent of vCenter Server. For this reason they come in 2 flavors (actually 3) depending on the platform:
- ESXi - NSX's version of vswitch which is implemented as an opaque switch in vSphere
- KVM - VMware's version of OpenvSwitch
- cloud and bare metal - NSX agent
An opaque switch is a network created and managed by a separate entity outside of vSphere. In our case logical networks that are created and managed by NSX-T. They appear in vCenter Server as opaque networks and can be used as backing for VMs. Although not a new thing , they are different from the NSX-v vswitches. This means that installing NSX-T in a vSphere only environment will still bring in the opaque networks instead of the NSX-v logical switches.
4. Routing
Differences are introduced at routing level where a two tiered model is being introduced by NSX-T. A very interesting blog article is here and I briefly will use a picture from it:
In a very short explanation:
- Tier-0 logical router provides a gateway service to the physical world
- Tier-1 logical router provides services for tenants (multi-tenancy) and cloud management platforms
Not both tiers are needed - depending on the services needed, only one tier can be implemented.
In a way, NSX-v could provide the same tiered model using Edge Services Gateway (ESG's), but in certain designs the routing paths were not optimal. NSX-T delivers optimized routing, simplicity and more architectural flexibility. Also, with the new model, Distributed Logical Router (DLR) control VM has been removed.
I will let you decide which of the changes briefly presented above are more important and I will just list them below:
- standalone (vCenter independent)
- multi hypervisor support
- container integration
- GENEVE
- NVDS and OpenvSwitches
- multi tiered optimized routing
However, if you are moving around the network virtualization world and haven't picked up on NSX-T, maybe it's time to start.
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