ESXi vswitch - Redirect external DHCP Server from one Ethernet to another

[ammannlu]

Hi

I am running ESXi 6.7 on a server. The network has a vswitch (vSwitch0) which is default, attached to this vSwitch are two physical ethernet ports, for the sake of simlicity lets call them eth0 and eth1.

i use a firewall which supplies the vswitch with dhcp request (this is a physical connection from a lan port of the firewall to eth0 of the server).

all vms running on this vswitch successfully get an ip.. so far so good

what i cannot do, is fairly uncommon:

if i connect now a ethernet cable from the servers eth1 to my pc, what i would expect is an ip, therefore a route as follows: PC-eth to server eth1, over vswitch0 to eth0 to the firewall (which in this case is a simple dhcp server).

THIS DOES NOT WORK.

does someone know why not and if this issue is addressabe/solvable? or, if not, can you explain to my why this wont work?

thanks.

[Beingnsxpaddy]

Hi ammannlu​, As far as I understand, have connected 2 NIC cards "uplink to the vSwitch" out of which 1st uplink is connected to the firewall, which is serving as DHCP.

When you connect a physical machine to second uplink, then you are not able to get the IP from your firewall which is connected to your vSwitch with first uplink.

Correct me if I am wrong.

If yes then, can you collect wireshark logs from a mirrored port or if its a VM then promiscous mode, to see what happens to your discover packet.

Regards

Pradhuman

VCIX-NV, VCAP-NV, VCP2X-DCVNV

[ammannlu]

@Beingnsxpaddy

Thanks. Yes as you say, 1 vswitch, 2 uplinks.

So do you say it technically should work?

Otherwise what makes me already a bit suspicious is the name itself, UPlink.. i actually wonder if ever someone did need this cause to be fair its basically a software-switch which has not a special performance

But in my case it would be just really practical. On the other hand, a lot of people run their firewall on the server itself... therefore, dhcp requests are also "leaving" the physical server.

[Beingnsxpaddy]

@ammannlu Logically what you are doing should work, as an uplink is also a port which has more bandwidth than normal ports, thats why wireshark or netmon captures would show what is running underneath.