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Self-managed machines in the Informatics Forum

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A 'self-managed machine' on our network is any machine other than either a desktop running the DICE managed version of Linux, or a 'Windows Managed Desktop'. For example, a laptop (running any OS), a desktop running Ubuntu, or a bespoke piece of equipment which has a wired network interface - all of these are 'self-managed machines' in our terminology.

In the Informatics Forum, self-managed machines are located on one of three separate subnets:

  • Machines using a dynamically assigned IP address are located on the subnet, which is carried on the VLAN 'DHCP'.
  • Machines using a fixed IP address are located on either the or subnets, which are carried on the VLANs 'SM164' and 'SM197' respectively.

The default position is that a self-managed machine will be located on the subnet, and will automatically acquire a dynamically-assigned (i.e. 'leased') IP address via DHCP. In this case, it is not necessary to register the MAC address of the machine with us: all that is necessary is to connect the machine to a network port which has been configured to be on the 'DHCP' VLAN. In practice, most laptops in use in the Informatics Forum are operated in this way.

If a permanently-fixed (i.e. 'static') IP address is required, fill in a Support Request giving the reasons why you need such an address, along with the MAC address of the machine, a suggested DNS hostname for it, and the label of the network port to which it will be connected. (An example reason might be that your machine is a server of some kind which needs a fixed address in order that it can be located by clients.) Assuming that the request is reasonable, the Computing Support team will then add the MAC address of the machine to our DHCP tables, reconfigure the network port to be used so that it is on the appropriate VLAN, and will tell you when this has been done. At that stage, the machine can be connected to the network port and should acquire its fixed address.

Note that firewall exemptions to allow inbound traffic through the Informatics firewall to a self-managed machine can only be granted if that machine has been allocated a fixed IP address.


Irrespective of whether you use a dynamically-assigned address or a permanently-fixed address, you should always configure your self-managed machine to acquire its complete TCP/IP configuration via DHCP. Doing so is the only way your machine can be guaranteed to acquire correct IP routing configuration, correct DNS server configuration, etc.: on our network, these configurations can and do change from time to time.

In particular, unless your machine doesn't support DHCP at all, please never hard-configure the IP address of the machine.

As implied above, a self-managed machine will only function correctly on our wired network if it is connected to a network port which has been configured to be on the appropriate VLAN. You can find out which VLAN any network port is currently configured to be on by using the search facility on our Forum network monitoring or AT network monitoring page: just enter the complete number of the port (e.g. 1/A/D6/1/22) in the 'Room number or outlet label' search box.

Note: Any user of a self-managed managed machine should read and understand the self-managed machines policy.

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