?
Solved

Trying to Understand MAC Address with a VM Machine

Posted on 2009-05-07
4
Medium Priority
?
632 Views
Last Modified: 2013-11-09
How does a VM machine change the MAC addresses on a single NIC?  Does the NIC have multiple MAC addresses at any given time?  Is the VM swapping out MAC addresses based on the needed address.  Or, does it work some other way?
0
Comment
Question by:jdana
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
4 Comments
 
LVL 1

Accepted Solution

by:
sryckman earned 336 total points
ID: 24330545
Remember that the VM does not have a physical NIC.   You may have mapped the virtual machine's virtual NIC to a physical NIC - but in the virtual machine it's just software.   The physical NIC on the machine just acts as a switch and forwards the traffic.   Thus the MAC address for a VM can be whatever the VM wants it to be.
0
 
LVL 10

Assisted Solution

by:ashwin_kumar525
ashwin_kumar525 earned 332 total points
ID: 24330920
The MAC address will be dynamically generated for each VM you mount. You can also set it to static if you want. This is not only for VMs, we can also change the MAC for your physical machine using third party softwares.
0
 
LVL 3

Assisted Solution

by:ranit8
ranit8 earned 332 total points
ID: 24364859
"The physical NIC on the machine just acts as a switch and forwards the traffic."

What sryckman said is right, and there are 2 possible ways, depending on the implementation:

Either the host works as an ARP PROXY so the external network machines send traffic directed to the VM guests's IP address to the host's MAC address, and the host sends it to the VM with the VM's MAC address as destination (much like NAT, but a layer below).

Or the host physical NIC is set at promiscuous mode, so whenever the address of the received frame matches the physical MAC or one of the virtual machines MAC, the frame is processed accordingly.
0
 

Author Closing Comment

by:jdana
ID: 31579207
sryckman - Thanks for the clear summary.  
ranit8 - Thanks for the definition of ARP PROXY and promiscuous mode.  Both concepts are now in my notes.
0

Featured Post

10 Questions to Ask when Buying Backup Software

Choosing the right backup solution for your organization can be a daunting task. To make the selection process easier, ask solution providers these 10 key questions.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

It Is not possible to enable LLDP in vSwitch(at least is not supported by VMware), so in this article we will enable this, and also go trough how to enabled CDP and how to get this information in vSwitches and also in vDS.
Arrow Electronics was searching for a KVM  (Keyboard/Video/Mouse) switch that could display on one single monitor the current status of all units being tested on the rack.
How to install and configure Citrix XenApp 6.5 - Part 1. In this video tutorial we have explained step by step installation of Citrix XenApp 6.5 Server on Windows Server 2008 R2 is explained in this video. We have explained the difference between…
In this video tutorial I show you the main steps to install and configure  a VMware ESXi6.0 server. The video has my comments as text on the screen and you can pause anytime when needed. Hope this will be helpful. Verify that your hardware and BIO…
Suggested Courses
Course of the Month13 days, 15 hours left to enroll

801 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question