ESXi: can server ports be used as a switch?

Joined
Sep 10, 2019
Messages
24
The title says it all and perhaps I should try before asking but I think this is an interesting topic any ways.

Say I have a server with multiple ethernet ports if I connect a PC directly to one of the spare NICs (cross-ethernet being a must for PC of course), assuming it's all within the same subnet say /24, would the communication end to end from PC to router via ESX work out of the box?

Code:
                       +------------------------------------+                         
                       |                                    |                         
                       |                                    |                         
+---------------+      |               ESXi                 |     +--------------------+
|               |      |                                    |     |                    |
|               |      +------+                     +-------+     |                    |
|  ROUTER       |------| NIC1 |                     | NIC2  |-----|       PC           |
|               |      +------+                     +-------+     |                    |
|               |      |                                    |     |                    |
|               |      |                                    |     |                    |
+---------------+      |                                    |     +--------------------+
                       |                                    |                         
                       +------------------------------------+

Asked in different words: does ESX bridge all the ports by default with no layer 2 filtering?

Thanks :)
 

cjcox

[H]ard|Gawd
Joined
Jun 7, 2004
Messages
1,828
Logically, and properly, my mind says no. You don't want ESXi to introduce networking issues. I can't say this for sure, but mentally, I say no. You don't want "side effects" caused by ESXi.
 

Dopamin3

Limp Gawd
Joined
Jul 3, 2009
Messages
166
I don't think so. Cool idea but ultimately best to buy a cheapo Netgear/TP Link switch.

Take a backup and mess with config if you want to try it. Don't think you need a crossover cable if you get it working like a "switch", also with Auto MDI-X you often don't need them anyway.
 

Eulogy

2[H]4U
Joined
Nov 9, 2005
Messages
2,230
The title says it all and perhaps I should try before asking but I think this is an interesting topic any ways.

Say I have a server with multiple ethernet ports if I connect a PC directly to one of the spare NICs (cross-ethernet being a must for PC of course), assuming it's all within the same subnet say /24, would the communication end to end from PC to router via ESX work out of the box?


Asked in different words: does ESX bridge all the ports by default with no layer 2 filtering?

Thanks :)
You should read up on the standard and/or distributed virtual switches. But you can pretty easily make "ROUTER" talk to "PC" with "ESXi" in the middle, yes. Would not be how I'd do it - at the very least I'd get a cheap, unmanaged switch in there, and if your router is WAN connected, I would absolutely not have it on the same /24 network. But what you do is up to you.
 
Joined
Sep 10, 2019
Messages
24
Thanks that's the answer I was looking for. I did mention PC to make it simpler in truth is a small device with an IP that I consult briefly like once/week or so, so no traffic generated what so ever.
I also appreciate that if ESXi is down for whatever reason this device will not be reachable and I'm ok wit it.
What this design gives me is to use a single (very long) cable between router and ESXi while maintaining reachability without having to install additional HW such an external switch.

I don't get your comment on the WAN involvement though? The router does natting on the WAN interface of course so the ./24 comment relates to LAN connectivity only. It just wanted to mention that as "PC" to Router is Layer2, ESXi needn't route packets that's all. :)
 
Last edited:

Eulogy

2[H]4U
Joined
Nov 9, 2005
Messages
2,230
Thanks that's the answer I was looking for. I did mention PC to make it simpler in truth is a small device with an IP that I consult briefly like once/week or so, so no traffic generated what so ever.
I also appreciate that if ESXi is down for whatever reason this device will not be reachable and I'm ok wit it.
What this design gives me is to use a single (very long) cable between router and ESXi while maintaining reachability without having to install additional HW such an external switch.

I don't get your comment on the WAN involvement though? The router does natting on the WAN interface of course so the ./24 comment relates to LAN connectivity only. It just wanted to mention that as "PC" to Router is Layer2, ESXi needn't route packets that's all. :)
You're exposing your ESXi host and everything downstream from there to the public internet with no real firewall, IDS, or protection of any kind.
 
Joined
Sep 10, 2019
Messages
24
You're exposing your ESXi host and everything downstream from there to the public internet with no real firewall, IDS, or protection of any kind.

This is a home network and the router is a SOHO router (installed with FreshTomato) and does come with basic firewall capabilities even though it is not an enterprise class I admit.

Thanks
 
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