ESXi Guest not getting DHCP from cable modem

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LightningCrash

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Hi guys. I had a problem this weekend and I want to try to get some troubleshooting ideas before I give it another go.

Host: ESXi 5.5u1
Mobo: Supermicro X7SBE
NIC: Intel® 82573V + Intel® 82573L (Yes I had to roll that in to 5.5)
Old Modem: Moto SB5121
New Modem: Moto SB6121

Guest: Sophos UTM 9
Guest try#2: CentOS 7

I have a vSwitch configured for the RED interface, using the second NIC. It is dedicated to the cable modem and the UTM VM.

On the SB5121, everything works just fine.
When I switch to the SB6121, and the modem is provisioned, the UTM VM doesn't get a DHCP offer.
Before the modem was provisioned, I got a 172.x address and the ISP captive portal "Please call us to configure your modem."
I can plug the SB6121 into my laptop and it works just fine. Plug back into the ESXi host, no joy.
I ran tcpdump on the VM and I see a dhcp request go out on the vnic, but it never receives a response. I swapped in a CentOS 7 VM and got the same issue.
I restart the modem after almost every VM or host change.

What I have tried on the ESXi side:
  1. Restarting the ESXi host
  2. Restarting the VMs
  3. Tried out a CentOS 7 VM on that interface
  4. Monkeyed with promiscuous mode on the vswitch and port group.
  5. Set the MAC of the VM VNIC to be the MAC of the physical NIC
  6. Moved the VM's second VNIC temporarily to the inside LAN, which got an IP from DHCP.


I'd like to get some recommendations for things to try on the next go around, which might be this weekend or so. Any ideas?

My to-do list so far:
  1. Bug the cable company more about it (I got the captive portal page, so I got DHCP once, right?)
  2. Throw a guad GbE NIC in a machine, make a bridge from 2 ports and run tcpdump on the interfaces.
  3. Use a quad GbE NIC in the ESXi machine instead of the unsupported onboard NIC (doubt this will help but it's trivial to try)

Thank you in advance for your ideas.
 
Have you played with forged transmits and mac address changes as well as promiscuous?
 
Err.. from the modem? What? Why are you putting guest OSes directly on the internet and not behind a NATbox? ("router") BAD BAD BAD idea there, go get yourself one now.

As to the cable modem thing, two problems here:
1: you need to call and activate your new modem
2: it's very likely you'll only get one IP from the ISP, hence the NATbox requirement.
 
FnordMan said:
Err.. from the modem? What? Why are you putting guest OSes directly on the internet and not behind a NATbox? ("router") BAD BAD BAD idea there, go get yourself one now.

As to the cable modem thing, two problems here:
1: you need to call and activate your new modem
2: it's very likely you'll only get one IP from the ISP, hence the NATbox requirement.
Click to expand...

Because you can virtualize the router. I have a virtualized RRAS server running in my VMware environment. One of its virtual interfaces is on a completely different VLAN than everything else in my network. Only that "WAN" interface on the virtual RRAS server and the cable modem live on that VLAN keeping it segregated from the rest of my network and everything has to go through that virtual RRAS server to get to the internet.

Same principal with a virtualized pfsense router, Endian, etc.
 
LightningCrash said:
Nope, what do you think they would do?
Click to expand...

Just taking a stab. I had run sophos UTM virtualized on esxi and it worked fine. I now use pfsense and it does too. Provider is dhcp-based so this would have had to work for me too. I just checked my WAN bridge in esxi and all 3 settings are enabled. Might want to give it a try...
 
I know cable boxes are picky, such as needing a reboot every time you plug in a different device to the modem. I am assuming that the modem recognizes the first mac it sees and will only talk to that device. Is it possible that it is seeing the mac of the physical nic, and will not talk to the vnic on its different mac address? I'm pretty good with vmware but never played around with the vswitch settings that much. Can you try directly attaching physical nic2 directly to the vm instead of "bridging" with a vswitch?
 
tporter said:
I know cable boxes are picky, such as needing a reboot every time you plug in a different device to the modem. I am assuming that the modem recognizes the first mac it sees and will only talk to that device. Is it possible that it is seeing the mac of the physical nic, and will not talk to the vnic on its different mac address? I'm pretty good with vmware but never played around with the vswitch settings that much. Can you try directly attaching physical nic2 directly to the vm instead of "bridging" with a vswitch?
Click to expand...

Well I did set the vnic of the VM to have the same MAC as the physical NIC. That should have had the same effect, right?

I don't know how you would give the nic directly without a vswitch, though. No vt-d on this box. Ideas?
 
ouch.. no vt-d may mean out of luck. I have never tried cable modem directly to vm so I will defer to other members at this point.
 
I have an esxi 5.1 host connected to a cable modem and all VMs get an IP via DHCP no problem.

This is with a vswitch configured on that interface. Cable modem is a Motorola 6120
 
Maybe not, grasping at straws here, since I have the exact same config and it works for me. I was hoping vsphere was blocking something.
 
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