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Self-managed machines in Appleton Tower

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.

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

In Appleton Tower, self-managed machines are located on one of three separate subnets:

  • Self-managed machines in staff offices using static IP addresses are located on the 129.215.199.0/25 subnet, which is carried on the VLAN 'R'.
  • Self-managed machines in staff offices using dynamically-assigned IP addresses are located on the 129.215.199.128/25 subnet, which is carried on the VLAN 'ATDHCP'.
  • Self-managed machines in 'open areas' (i.e. areas accessible to students) using both dynamically-assigned and static IP addresses are located on the 192.168.105.0/24 subnet, which is carried on the VLAN 'ATopen'.

The default position is that a self-managed machine in a staff office will be located on the 129.215.199.128/25 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 'ATDHCP' VLAN.

Likewise, the default position for self-managed machines in 'open areas' is that they will automatically acquire a dynamically-assigned IP address. In practice, most laptops used by students on the wired network in Appleton Tower will be 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 (if necessary) so that it is on the appropriate VLAN, and will tell you when all of 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.

Also note that, for auditing reasons, machines on the subnet carried on VLAN ATopen are restricted to accessing only the University of Edinburgh network; they cannot access the network beyond that. Students who want to use a laptop in Appleton Tower to access the wider Internet should do so via a wireless connection instead.

Important:

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 in Appleton Tower is currently configured to be on by using the search facility on our AT network monitoring page: just enter the complete number of the port (e.g. 5/164) in the 'Room number or outlet label' search box.

Last reviewed: 
12/01/2022

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