MAC address mismatch

[kske]

When setting up a linux host....if i initially create >3 network interfaces, there are MAC address mismatches between VMWare and the host OS. for example, eth0, 1, and 2 may match the first 3 VM MACs but subsequent ones do not. Is this a documented issue?

[admin]

I really didn't your question. Can you please try to elaborate your question?

What do you mean by mismatch from VMware and Host OS ? What do you mean by mismatch... MAC's for each card are bound to be unique and hence different.

[kske]

When you bring up a VM with >3 ethernet interfaces.....there is not a direct match for say ethernet1 <-> Network Adapter 1, ethernet2<->Network Adapter 2, etc....you have to manually match the MAC addresses of your host OS to those of Network Adapter 1-n. If you bring up the VM with 3 or less ten this is not an issue.

[Texiwill]

Hello,

Actually, when you have > 1 adapter, you should match the Mac Addresses from seen in vCenter and the VM. Otherwise it could just be guesswork based on the order in which linux adds them to the system which, as previously stated, is based on PCI address and the types of devices in use. When you have more than one of the same device type (E1000, VMXnet, etc) then you need to match your mac address between the two systems. If you use distinct device types then it is easy enough to match without actually looking at vCenter.

Best regards,
Edward L. Haletky
VMware Communities User Moderator, VMware vExpert 2009, 2010, 2011,2012,2013,2014

Author of the books 'VMWare ESX and ESXi in the Enterprise: Planning Deployment Virtualization Servers', Copyright 2011 Pearson Education. 'VMware vSphere and Virtual Infrastructure Security: Securing the Virtual Environment', Copyright 2009 Pearson Education.

Virtualization and Cloud Security Analyst: The Virtualization Practice, LLC -- vSphere Upgrade Saga -- Virtualization Security Round Table Podcast

[MKguy]

This is not an "issue". On Linux, eth interfaces are typically numbered by the PCI address or PCI slot number of the device. These PCI properties are not necessarily corresponding to the network interface numbering you see in the VM edit settings, which basically just counts vNICs up from 1.

You can check the PCI address/slot number on your Linux guest with lspci:

# lspci -v | grep Ethernet -A2

0b:00.0 Ethernet controller: VMware VMXNET3 Ethernet Controller (rev 01)

        Subsystem: VMware VMXNET3 Ethernet Controller

        Physical Slot: 192

You can write custom udev rules to handle the interface numbering like:

http://www.cyberciti.biz/faq/howto-linux-rename-ethernet-devices-named-using-udev/

http://www.debianhelp.co.uk/udev.htm