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Community Member

DHCP issue inside a VM connected via wireless network

Hi,

   I'm having the following problem. I have a notebook that associates to a WiFi (WLAN) netwok with a WLC 2106 that receive it's IP address from a DHCP server. When I turn on a virtual machine (with VMware o Virtual Box) inside that notebook, that VM doesn't receive an IP address from the DHCP server. The virtual network adapter that is inside the VM is configured as bridge mode, it is to say that it connects to the physical network through the notebook wireless adapter. Therefore, the AP and the WLC see the virtual machine and the notebook as they were two different clients, with two different MAC addresses but using the same physical network adapter. It's a very common scenario when you work with virtual machines.

   The question is. Could be any configuration inside de WLC that doesn't permit to lease more than one DHCP IP address to the same physical network adapter. Because if I configure an static IP address inside the VM it works OK. The problem is only receiveing a DHCP address.

Thanks.

Guido.

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

It will not work.  See this post:

https://supportforums.cisco.com/thread/329343

https://supportforums.cisco.com/thread/2065405

-Scott
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18 REPLIES
Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

It will not work.  See this post:

https://supportforums.cisco.com/thread/329343

https://supportforums.cisco.com/thread/2065405

-Scott
*** Please rate helpful posts ***
Cisco Employee

Re: DHCP issue inside a VM connected via wireless network

Starting in 7.0.116.0, we added support for non-cisco WGBs with the passive client feature on a wlan. This feature will also apply to VMware and virtual clients -- it is available on the 2100, 2500, 5500 WLCs, although it is not available on the 4400 series (WISM/3750) due to architecture limitations.

Guido, you can try enabling the passive client feature on your WLAN to see if this helps resolve the issue.

-Pat

Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

This is good to know.... but I thought that passice client feature was in the 7.0.98.0 also?

-Scott
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Cisco Employee

Re: DHCP issue inside a VM connected via wireless network

Hi Scott,

You're right, we introduced the passive client feature in 7.0.98.0. However, we enhanced this feature in 7.0.116.0 to include 3rd-party workgroup bridge support, which happens to also impact clients such as VMware and other virtual machines:

http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn7_0_116_0.html#wp690316

-Pat

Community Member

DHCP issue inside a VM connected via wireless network

I am having a similar problem, does anyone know if there is a command like this for autonomous access points?

Cisco Employee

DHCP issue inside a VM connected via wireless network

Autonomous AP architecture should not have this same issue -- I do not believe the MAC/IP address binding limitation is present.

If you are experiencing issues, I would urge you to open a TAC service request.

You could also run a packet capture on the AP switchport to see if the DHCP discover/requests from the VM client are making it on the wire.

-Pat

Community Member

DHCP issue inside a VM connected via wireless network

Hi,

I have a Cisco 897 with an integrated AP in autonomous mode. I've tried different software versions, but still I can't receive an IP address from the DHCP server with host virtualization and bridge mode as described above.

I've done a wireshark capture of it, and simply do not receive any reply to my DISCOVER packets. i do however see my DISCOVER reach the router (debug ip dhcp server). If I configure an IP address manually, it works.

Do you have any idea why or what I could be missing?

Thanks,

/JZ

Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

You have a router with an integrated AP and your trying to use the AP as a WGB?

Sent from Cisco Technical Support iPhone App

-Scott
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Community Member

Re: DHCP issue inside a VM connected via wireless network

Hi Scott,

No, I'm not trying to configure is as a WGB...

Thanks,

/JZ

Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

So your issue is different. Your just trying to get the AP to bridge to the router I'm guessing?

Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***
Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

Take a look at this doc

https://supportforums.cisco.com/docs/DOC-16020

Sent from Cisco Technical Support iPhone App

-Scott
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Community Member

Re: DHCP issue inside a VM connected via wireless network

Hi,

No, my issue isn't different IMO. I have a working AP where clients can bridge to the router (dhcp server) and get an IP address. Where it does not work is when I take one of my computers and install a virtual computer on it, configure its vNIC for bridging to the Wi-Fi NIC of the host and try to lease an IP address.

I hope this clearifies my issue.

Thanks,

/JZ

Hall of Fame Super Silver

Re: DHCP issue inside a VM connected via wireless network

Yeah that still isn't fixed at least on the WLC side. From what you are seeing also, it will not work on the autonomous side either.

Sent from Cisco Technical Support iPhone App

-Scott
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Community Member

I had the same issue and it

I had the same issue and it looks that the AP in autonomous mode does not forward DHCP replies to the virtual computer. After some troubleshooting I found a solution (similar to chixson001), see https://supportforums.cisco.com/discussion/12237801/problems-dhcp-and-virtual-pc-connected-ap-autonomous-mode

 

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