As well as the regular routed IP data network connection, the UDN (University Data Network) supports some layer 2 (switched) services.
VLANs presented to institutions between sites will use tags in the Global range of the UDN VLAN numbering scheme.
Contents
More information on these is given below.
Additional routed VLAN
As part of the PoP switch service, institutions get a routed data VLAN with the UDN (which can have multiple IP ranges). If an institution requires an additional VLAN (e.g. for an administratively separate part of their institution), they can request one is set up, either with new addresses or by moving some of their existing addresses across.
Institutions can have one additional VLAN (i.e. up to a total of two) as part of the standard PoP charge. Any VLANs beyond this are charged for.
Each VLAN can be configured according to a different model for routing (e.g. edge connection / directly-routed or statically routed). Full information about available options is on the 'IP routing on institutional connections' page.
Infrastructure service VLANs provided for a specific service (e.g. voice, wireless access points, BMS, etc.) are paid for by the service itself and do not count against this limit.
Local PoP VLAN service
An institution with a PoP switch may wish to have a local VLAN which is used to provide internal connectivity between ports on the PoP, not uplinked directly to the UDN. For example, the institutional may loop a firewall through the PoP, with the "outside" linked to the regular UDN data VLAN and an "inside" fed down to internal switches and hosts.
This service is described in details on the PoP equipment page.
Inter-site VLAN service
Note: as of 2025, this service is no longer available available for new customers: existing VLANs will continue to be supported, for the time being, but will gradually be phased out over the next few years.
There are two main ways in which VLANs can be provided between sites. Which is available depends on whether and institution has a PoP or direct connect (as used to deliver BGP directly between UDN and institution routers). The services cannot be mixed: if one site has a PoP and the other directly links with BGP, the VLAN service is not available.
Both variants of the service are charged-for.
Inter-site VLAN between PoP switches
An institution may wish to extend a VLAN across separate sites, fed through different PoPs, as part of a private, internal network (much like a local VLAN, but across PoPs).
If institutions need to do this, they will need to use a dark fibre GBN circuit. The recommended way to link sites privately is to use a layer 3 service like an MPLS VPN.
Other VLAN services
In addition to the layer 2 VLAN services themselves, the UDN can supply other VLANs to institutions through their PoP, in addition to their main data VLAN. These include MPLS site VLANs for other institutions, infrastructure service network VLANs and bridged wireless SSID VLANs.
Prices
VLAN services are a charged-for service on a per-VLAN basis:
|
Annual Charge |
New Installation |
|
| Additional routed VLAN via PoP | £74 | N/A |
| Inter-site VLAN (no longer available to new customers) | £74 | N/A |
All prices are subject to VAT, where applicable.
Last updated: 16th June 2025