HP Virtual Connect: Common Myths, Misperceptions, and Objections, Second Edition

A virtualized MAC address or WWN is an address that is not really owned and used by a physical

NIC or HBA. Often, a virtualized address is an address that replaces the real MAC or WWN

address of a physical NIC without the server’s knowledge. In other words, the server thinks it is

communicating on the network with MAC address X, however, some device (switch) is replacing real

MAC address X with a virtual MAC address Y. This process is effectively Network Address

Translation (NAT) of the address by the switch or router. Many of the benefits of MAC address

management are lost in this type of implementation.

A managed MAC address or WWN, provided by Virtual Connect, is an address that actually is

owned and used by a physical server NIC or HBA. Simply put, the server has been assigned, by the

administrator, to use a specific address on a specific physical NIC or HBA port. These managed

MAC addresses or WWNs appears to the server as the MAC addresses and WWNs that were

burned into the physical NICs and physical HBAs at the factory.

The benefits of VC Managed Addresses are:

• Advanced flexibility and mobility without switch scripting

Virtual Connect provides consistency and mobility of managed MAC addresses and WWNs

within the data center using “server profiles”. A server profile contains the server’s internal

identity (server serial number, UUID, BIOS settings, FC boot parameters, etc.) and a server’s

external identity (MACs, WWNs, VLAN assignments, and SAN fabric assignments). A server

profile can remain assigned to a server blade bay in an enclosure to maintain the internal

and external identity of the server constant no matter what hardware is installed in the slot.

However, Virtual Connect also allows the movement of the server profile, with the entire

server identity, to any server blade bay in any HP blade enclosure across the data center(s).

The movement of a server profile is as simple as a few clicks in the Virtual Connect Web UI

or the VC CLI. In addition, VCEM can automate the movement of the server profile. In all

cases, the movement of a server profile with the server’s identity does NOT require a

separate process to apply a reconfiguration script against an external Ethernet or Fibre

Channel switch. With Virtual Connect, the movement of a server profile and the server’s

identity is transparent to the Ethernet and Fibre Channel switches.

• WYSIWYG - What You See (on the server) Is What You Get (on the network)

There is no discrepancy between what the server thinks its MAC address and WWN are and

what the external network sees as the server’s MAC address and WWN. Having only one

real MAC address or WWN to manage (versus two with virtualized addresses) per port

dramatically reduces the complexity of troubleshooting network and SAN related issues.

• Server application licensing is maintained after hardware changes

Many server application licensing mechanisms can key off the server’s MAC addresses. If the

server’s MAC address changes (replacing a failed NIC, booting server image on a different

physical server, etc.), then the application licensing may require re-licensing using the new

MAC address. Virtualized MAC addresses and WWNs do not address this problem.

However, VC’s use of managed MAC addresses and WWNs does prevent this problem

since the server image (OS) will always see the VC managed MAC address and WWN

regardless of which physical server the image is running on.

• No Performance impact on network and storage devices

Virtualized MAC addresses and WWN can require that a network device (for example,

switch) manipulate every frame a server transmits to replace the server’s MAC address or

WWN with the virtualized address. Also, when the addresses are edited within the frame by

the network device, the frames checksum (CRC) has to be recomputed by the network device.

The more frames a server transmits, the more work the network device has to do, which can