Manual Assign Ip Address Mac

  1. Enter the same address as the one that you typed in step 2. Example: ping -l 479 Restart the machine, and the specified IP address is configured in the machine.
  2. Some routers can pre-assign DHCP so the same device always gets the same IP address, but not all can. (DHCP Reservation is the buzzword) If the router can do DHCP reservation, that is often.

If you’re working in a Cisco network and assigning addresses to your IPv6 network cards, you need to know that just like IPv4 addresses there is a network portion of the address and a host portion of the address.

Both portions are 64-bits long, so the first 64-bits of an IPv6 address is the network address (sometimes referred to as a network ID or network prefix), and the last 64-bits of an IPv6 address is a unique host ID for the specific network ID. The four methods of assigning IPv6 addresses are

Add your device’s IP Address and MAC Address. The IP Address you choose will need to fall within your router’s DHCP UP Address Range (see the DHCP Server Settings section directly above). You should be able to locate your devices MAC Address on the bottom of the device itself.

  • Manual Interface ID Assignment: An address is manually assigned to an interface. This is fairly easy to do with most Cisco devices from the interface configuration with a command like

    As with any manual system, it is easy to assign one address to one interface; but you may not want to manually assign addresses to every device on your network manually.

  • EUI-64 Interface ID Assignment: This is similar to a full manual address, but instead of specifying full address, you configure only the network portion of the address, and the remainder of the address is derived from the interface’s Media Access Control (MAC) address. When configuring this from the interface prompt, the command looks like this:

    The MAC address on your network interface is a 48-bit number and may sometimes be referenced as MAC-48 to denote the length. Because the MAC address is a unique identifier, it can also be referred to as an Extended Unique Identifier (EUI) of 48-bits or EUI-48. MAC refers to a network interface identifier, whereas EUI-48 could be assigned to other devices.

    The MAC address on your network interface is a 48-bit number and may sometimes be re When designing IPv6, the designers wanted to have unique identifiers that were larger than the current EUI-48, so they lengthened the identifier to 64-bit and created the EUI-64 identifier. So an EUI-64 is simply a globally unique identifier.

    This configuration makes address assignment much easier because all devices on the same data link share the same network ID, and all you need to have automatically assigned is the host ID, which is guaranteed unique because it is based on the already globally unique MAC address.

  • Stateless Auto-Configuration: This is by far the easiest way to configure an IP address on an interface, allowing full automatic configuration. This configuration mode was created to allow all devices on the same data link to automatically configure themselves, reducing administrative overhead for the network administrators. In addition to full auto-configuration, Stateless Auto-Configuration sends a request for a router advertisement(RA), which is used by the client as a 64-bit network ID prefix to the client’s IP address.

    The MAC address on your network interface is a 48-bit number and may sometimes be re This means that if you have configured your routers with their 64-bit network IDs, your network devices use those network IDs; otherwise, all your network IDs for your internal network are assigned automatically. The 64-bit network ID could be a global or private address, but the remaining 64 bits of the address are chosen automatically by the client.

  • DHCPv6 (Stateful): Dynamic Host Configuration Protocol (DHCP) servers that have the appropriate extensions installed for IPv6 can process DHCP address requests. This process for handing out addresses is similar to IPv4; the server is configured with an address pool to hand out, and it randomly fills the address requests from this pool. This process allows for complete control over the assigned client IP address, as well as being able to view the list of assigned addresses.

    The MAC address on your network interface is a 48-bit number and may sometimes be re In DHCPv6, the client first checks for a router advertisement; and if there is, the client is allowed to use DHCP. If there is no router or the router allows for DCHP, the client sends a multicast request to all DHCP agents on the network; if there are no router advertisements or DHCP responses, the client uses the local-link address.

Manual Assign Ip Address Mac

You must have enough media access control (MAC) addresses to assign to the number of logical domains, virtual switches, and virtual networks you are going to use. You can have the Logical Domains Manager automatically assign MAC addresses to a logical domain, a virtual network (vnet), and a virtual switch (vsw), or you can manually assign MAC addresses from your own pool of assigned MAC addresses. The ldm subcommands that set MAC addresses are add-domain, add-vsw, set-vsw, add-vnet, and set-vnet. If you do not specify a MAC address in these subcommands, the Logical Domains Manager assigns one automatically.


The advantage to having the Logical Domains Manager assign the MAC addresses is that it utilizes the block of MAC addresses dedicated for use with logical domains. Also, the Logical Domains Manager detects and prevents MAC address collisions with other Logical Domains Manager instances on the same subnet. This frees you from having to manually manage your pool of MAC addresses.

MAC address assignment happens as soon as a logical domain is created or a network device is configured into a domain. In addition, the assignment is persistent until the device, or the logical domain itself, is removed.

Range of MAC Addresses Assigned to Logical Domains Software

Logical domains have been assigned the following block of 512K MAC addresses:

00:14:4F:F8:00:00 ~ 00:14:4F:FF:FF:FF

The lower 256K addresses are used by the Logical Domains Manager for automatic MAC address allocation, and you cannot manually request an address in this range:

00:14:4F:F8:00:00 - 00:14:4F:FB:FF:FF

You can use the upper half of this range for manual MAC address allocation:

Manual Assign Ip Address Mac

00:14:4F:FC:00:00 - 00:14:4F:FF:FF:FF

Automatic Assignment Algorithm

When you do not specify a MAC address in creating logical domain or a network device, the Logical Domains Manager automatically allocates and assigns a MAC address to that logical domain or network device. To obtain this MAC address, the Logical Domains Manager iteratively attempts to select an address and then checks for potential collisions.

Before selecting a potential address, the Logical Domains Manager first looks to see if it has a recently freed, automatically assigned address saved in a database for this purpose (see Freed MAC Addresses). If so, the Logical Domains Manager selects its candidate address from the database.

If no recently freed addresses are available, the MAC address is randomly selected from the 256K range of addresses set aside for this purpose. The MAC address is selected randomly to lessen the chance of a duplicate MAC address being selected as a candidate.

The address selected is then checked against other Logical Domains Managers on other systems to prevent duplicate MAC addresses from actually being assigned. The algorithm employed is described in Duplicate MAC Address Detection. If the address is already assigned, the Logical Domains Manager iterates, choosing another address, and again checking for collisions. This continues until a MAC address is found that is not already allocated, or a time limit of 30 seconds has elapsed. If the time limit is reached, then the creation of the device fails, and an error message similar to the following is shown.

Manually Assign Ip Address Macro

Duplicate MAC Address Detection

To prevent the same MAC address from being allocated to different devices, one Logical Domains Manager checks with other Logical Domains Managers on other systems by sending a multicast message over the control domain's default network interface, including the address that the Logical Domain Manager wants to assign to the device. The Logical Domains Manger attempting to assign the MAC address waits for one second for a response back. If a different device on another LDoms-enabled system has already been assigned that MAC address, the Logical Domains Manager on that system sends back a response containing the MAC address in question. If the requesting Logical Domains Manager receives a response, it knows the chosen MAC address has already been allocated, chooses another, and iterates.

By default, these multicast messages are sent only to other managers on the same subnet; the default time-to-live (TTL) is 1. The TTL can be configured using the Service Management Facilities (SMF) property ldmd/hops.

Each Logical Domains Manager is responsible for:

  • Listening for multicast messages

  • Keeping track of MAC addresses assigned to its domains

  • Looking for duplicates

  • Responding so that duplicates do not occur

If the Logical Domains Manager on a system is shut down for any reason, duplicate MAC addresses could occur while the Logical Domains Manager is down.

Automatic MAC allocation occurs at the time the logical domain or network device is created and persists until the device or the logical domain is removed.

Freed MAC Addresses

When a logical domain or a device associated with an automatic MAC address is removed, that MAC address is saved in a database of recently freed MAC addresses for possible later use on that system. These MAC addresses are saved to prevent the exhaustion of Internet Protocol (IP) addresses from a Dynamic Host Configuration Protocol (DHCP) server. When DHCP servers allocate IP addresses, they do so for a period of time (the lease time). The lease duration is often configured to be quite long, generally hours or days. If network devices are created and removed at a high rate without the Logical Domains Manager reusing automatically allocated MAC addresses, the number of MAC addresses allocated could soon overwhelm a typically configured DHCP server.

Manually Assign Ip Address Mac Address

When a Logical Domains Manager is requested to automatically obtain a MAC address for a logical domain or network device, it first looks to the freed MAC address database to see if there is a previously assigned MAC address it can reuse. If there is a MAC address available from this database, the duplicate MAC address detection algorithm is run. If the MAC address had not been assigned to someone else since it was previously freed, it will be reused and removed from the database. If a collision is detected, the address is simply removed from the database. The Logical Domains Manager then either tries the next address in the database or if none is available, randomly picks a new MAC address.