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What you are showing is a physical diagram and what appears to be a single IP subnet (x.x.x.0/22)<br />
<br />
In order to understand what may be best we (at least I do) would need to understand your L2 and L3 setup better. &nbsp;As an example. &nbsp;If you really only have a single subnet (x.x.x.0/22) that would imply a single L2 network. &nbsp;If you have a single L2 and L3 network, why are you running OSPF?
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The issue with option 2 is that as you add &nbsp;more ESXi hosts to the new switches you are limited to two uplinks to the layer 3 core. So depending on the utilization and how you have the network setup this could cause over subscription of the uplinks. So in general option 2 does not scale.<br />
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Depending on the utilization of the uplinks and the class of layer 2 switch that you are using, you may be able to use option 2, but why not connect right to the L3 core with new switches? So the answer is it depends on what the ESXi hosts are doing, how much capacity is available, etc .....<br />
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harbor235 ;}
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Without knowing more about the setup, I would say that option #1 should allow you more growth with out affecting performance. &nbsp;It depends on how much traffic from the ESX hosts actually has to go to the core.<br />
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If go with option#2 and you have a lot of traffic that goes from the ESX servers to the core, you will be increasing the amount of traffic that is flowing on the connections between your two existing L2 switched and your core. &nbsp;As harbor235 stated, this may not affect you at all depending on current utilization of those links.<br />
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The only downside I can think of with option #1 is that you could need more ports on your cores.
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OSPF is not relevant in a single L3 IP subnet
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Is there any document or design guide from vmware regarding how to scale the NSX design.
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Attached is the current NSX network design.<br />
I have L2 Switch connecting to the L3 Core switch. The ESXi hosts with NSX are connecting to the L2 switch.<br />
OSPF is running between the L3 Core switch &amp;&nbsp;the NSX.<br />
<br />
In the near future I will be running short of the L2 switch ports where the ESXi hosts are connected.<br />
For this I have 2 options<br />
<br />
Option 1: Setup 2 more L2 switches parallel to the existing &amp;&nbsp;connect the same to the L3 core switches. Similar to the existing setup.<br />
Option 2: Setup 2 more L2 switches below the existing L2 switches &amp;&nbsp;connect the ESXi hosts to the new L2 switches.<br />
<br />
Would like to know which option is the best considering the pros &amp;&nbsp;cons.<br />
<a href="https://filedb.experts-exchange.com/incoming/2016/08_w32/1109377/NSX_Design.png" target="_blank" class="file-inline" title="NSX_Design.png (54 KB)"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path d="M67.508 468.467c-58.005-58.013-58.016-151.92 0-209.943l225.011-225.04c44.643-44.645 117.279-44.645 161.92 0 44.743 44.749 44.753 117.186 0 161.944l-189.465 189.49c-31.41 31.413-82.518 31.412-113.926.001-31.479-31.482-31.49-82.453 0-113.944L311.51 110.491c4.687-4.687 12.286-4.687 16.972 0l16.967 16.971c4.685 4.686 4.685 12.283 0 16.969L184.983 304.917c-12.724 12.724-12.73 33.328 0 46.058 12.696 12.697 33.356 12.699 46.054-.001l189.465-189.489c25.987-25.989 25.994-68.06.001-94.056-25.931-25.934-68.119-25.932-94.049 0l-225.01 225.039c-39.249 39.252-39.258 102.795-.001 142.057 39.285 39.29 102.885 39.287 142.162-.028A739446.174 739446.174 0 0 1 439.497 238.49c4.686-4.687 12.282-4.684 16.969.004l16.967 16.971c4.685 4.686 4.689 12.279.004 16.965a755654.128 755654.128 0 0 0-195.881 195.996c-58.034 58.092-152.004 58.093-210.048.041z"/></svg>NSX_Design.png</a>
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NSX_Design.png

Attached is the current NSX network design.
I have L2 Switch connecting to the L3 Core switch. The ESXi hosts with NSX are connecting to the L2 switch.
OSPF is running between the L3 Core switch & the NSX.

In the near future I will be running short of the L2 switch ports where the ESXi hosts are connected.
For this I have 2 options

Option 1: Setup 2 more L2 switches parallel to the existing & connect the same to the L3 core switches. Similar to the existing setup.
Option 2: Setup 2 more L2 switches below the existing L2 switches & connect the ESXi hosts to the new L2 switches.

Would like to know which option is the best considering the pros & cons.

NSX Design

VMware, a software company founded in 1998,  was one of the first commercially successful companies to offer x86 virtualization. The storage company EMC purchased VMware in 1994. Dell Technologies acquired EMC in 2016. VMware’s parent company is now Dell Technologies.

VMware has many software products that run on desktops, Microsoft Windows, Linux, and macOS, which allows the virtualizing of the x86 architecture.  Its enterprise software hypervisor for servers, VMware vSphere Hypervisor (ESXi), is a bare-metal hypervisor that runs directly on the server hardware and does not require an additional underlying operating system.

VMware

Virtualization is the act of creating a virtual (rather than actual) version of something, including (but not limited to) a virtual computer hardware platform, operating system (OS), storage device, or computer network resources. Virtualization is usually the creation of a system that executes separate from the underlying hardware resources, or the creation of an entire desktop for systems located elsewhere, similar to thin clients.

Virtualization

Network design and methodology, also known as network architecture, is the design of a communication network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation. In telecommunication, the specification of a network architecture may also include a detailed description of products and services delivered via a communications network, as well as detailed rate and billing structures under which services are compensated.