Jump to: Scheme details, VLANs 1-999, VLANs 1000-4094, Institutional networks supported by the UIS
VLANs using IEEE 802.1Q are given tags/IDs between 1 and 4094. These tags can be used on links between the University Data Network (UDN - the University backbone network) and institutional networks and must match at both ends.
Care must be taken by network administrators to ensure that the IDs used for purely internal networks within their institutions (or the UDN itself), that do not need to pass across these links, do not clash with numbers which may be used for VLANs between networks (in particular, the UDN and an institution).
Whilst the distinction is only important if an institutional network is importing or exporting a VLAN, institutions should bear in mind that even if they have no intention of importing or exporting VLANs now, that may change in future. Institutions are therefore recommended to allocate VLAN numbers based on the scheme to avoid future renumbering problems.
Scheme details
Ranges of numbers are allocated for different purposes:
| Reserved | Reserved at the present time and must not be used. |
| Global | Allocated by UIS Networks for global use across the UDN; institutions must not allocate these numbers to their own VLANs. |
| Local | Allocated for use within and by an institution without danger of clashing with numbers used by VLANs used globally across the UDN. |
The tables below show which numbers are allocated to each of these categories.
VLANs 1-999
For tags in the form x | yz (1-999), a fairly complex scheme is used:
| x \ yz | x00 | x01 | x02-x09 | x10-x79 | x80-x89 | x90-x99 |
|---|---|---|---|---|---|---|
| 0yz | - | Local | Local | Local | Local | Local |
| 1yz | Local | Local | Local | Global | Global | Local |
| 2yz | Reserved | Reserved | Global | Global | Global | Local |
| 3yz | Reserved | Reserved | Global | Global | Global | Local |
| 4yz | Reserved | Reserved | Global | Global | Global | Local |
| 5yz | Reserved | Reserved | Global | Global | Global | Local |
| 6yz | Reserved | Reserved | Global | Global | Global | Local |
| 7yz | Reserved | Reserved | Global | Global | Global | Local |
| 8yz | Reserved | Reserved | Global | Global | Global | Local |
| 9yz | Reserved | Reserved | Global | Global | Global | Local |
VLANs 1000-4094
For VLAN numbers of 1000 and above, a much simpler scheme is in use:
| 1000-1999 | Local |
| 2000-3999 | Global |
| 4000-4094 | Local |
Institutional networks supported by the UIS
The UDN uses VLAN IDs <100 and in the range 1000-1999 for its own use but ensures that VLANs >=4000 are left unused, on each institutional network. Where the UIS provides local institutional services (for example the Managed Firewall Service), local VLANs must be in the range 4000-4094 to avoid clashes.
Last updated: 7th April 2021