Technical data

Utilizing Multiple IPs on a Single MAC

In current Meru implementations, a typical client machine (or station) is granted a

single IP Address per wireless adapter in use. However, with the growing use of

Virtual Machine models (provided by VMware, Parallels, etc.), a single station can run

multiple Operating Systems from a single client. With this release of Meru System

Director, each Virtual Machine can now be provided with an individual IP Address,

making it much easier to troubleshoot packet transmissions.

To support this function, the System Director ESS Profile screen has a new function

labeled MIPS, which is disabled by default. With this function enabled, packets are

bridged across from the “host”, or main, Operating System to the “guest”, or virtual,

system(s) as needed. The following notes apply:

 All data packets sent from the client will have the host OS MAC address as their

source address.

 All data packets sent to the client will have the host OS MAC address as their

destination address.

 Each OS has a different client hardware address that is transmitted as part of the

DHCP payload.

 “Guest” OS hardware devices have MAC addresses that start “00:0c:29”; this is

the global standard OUI for VMware. This hardware address is used by the DHCP

server to identify guest OSes, allowing them to be provided separate IP addresses.

 Grat ARP packets transmitted by any IP will have their corresponding unique client

hardware addresses.

 All broadcast packets received by the host OS will also be delivered to the guest

OS(es).

 All unicast packets received by the host OS will be delivered to the guest OS(es)

based on the packets’ destination IP address.

In order to support this capability, a command has been added to the CLI:

 show station multiple-ip—Displays all IP addresses provided by each individual

station along with MAC addresses (labeled ‘vmac’ for virtual devices). Note that

for the host device, the Client MAC and Virtual MAC will be identical.

Note:

 Only IPv4 address types are supported.

 All IP addresses belonging to a single station are assumed to be part of the

same VLAN.

 IP addresses provided to Virtual OSes are always dynamic; static addresses are

not supported.

 ICR is not supported when this feature is enabled.