VMware Networking Community
pcparts001
Enthusiast
Enthusiast

Different subnet/different vmkernel same vlan is common?

Hello

I don't know this place is right place to ask question about this, but this relates to HOL "HOL-SDC-1403 - VMware NSX Introduction"

so please forgive me.

In this HOL, all vmkernel's vlan have not configured.

But IP segment for some vmkernel is different.

How can that be possible?  In my understanding, even it is vmkernel port, different vlan id should apply to each different ip segment vmkernel port.

I've searched web but I couldn't find the answer....

Is this design common in vmware environment?  (Which means, multiple different IP segment vmkernel ports are available but is in same vlan or not at all)

Or this is just for some dependencies(such as nested environment)?

4 Replies
admin
Immortal
Immortal

This design isn't normally used, but there's no problem with it.

If your router supports secondary interfaces, you can configure a single interface with IP addresses from multiple subnets, and hosts on the same L2 segment as such interface can be in these different subnets.

grosas
Community Manager
Community Manager

pcparts001

How can that be possible?  In my understanding, even it is vmkernel port, different vlan id should apply to each different ip segment vmkernel port.


It's not a forced requirement to have a one to one subnet to Vlan mapping. 

You can have a VLAN 50 configured, and two hosts/interfaces/VMs configured with IPs in different subnets.

[   SWITCH   ]

v50         v50
|            |

1.1.1.1/24   2.2.2.2/24

Nothing prevents this configuration, but then it means for these hosts to communicate there needs to be a gateway reachable in the vlan for both subnets. 

It also means hosts across subnet boundaries are sharing a broadcast domain.Like the previous reply says; you wouldn't purposely design this way. 

You might be forced into a having to do this when facing IP exhaustion where you don't have the flexibility to redesign. 

Hope that helps!


_____________________________________
Gabe Rosas (VMware HCX team at VMware)
Blog: hcx.design
LinkedIn: /in/gaberosas
Twitter: gabe_rosas
pcparts001
Enthusiast
Enthusiast

Thank you for your answer.  It is very informative.

Reply
0 Kudos
pcparts001
Enthusiast
Enthusiast

Thank you for your detailed explanation.  It is very very helpful.

Reply
0 Kudos