UW-Madison IPv6 Allocation Guidelines

Explanation of IPv6 address space allocation guidelines for the UW-Madison campus network.

The UW-Madison campus has been allocated the IPv6 range 2607:f388::/32. The IPv6 addressing format gives the ability to allocate each campus network entity their own appropriately sized range of IPv6 addresses.

The goals of the allocation plan include:

Central Allocation size guidelines

Allocation size Reservation Size
Number of Subnets Allocation Guidelines Example
College, School, or Large campus entity Med School
/48 /47
65,536 Typical department/unit Waisman Center
4,096 Not allocated centrally
256 Not allocated centrally  
16 Not allocated centrally  
1 An individual end-user subnet.  

There may be special circumstances to use larger or smaller allocations, but these should be extremely rare. Network Engineering will work with each requester to make sure the appropriate size is determined.

Tips for Network Administrators

End-User Subnet size

As shown in the table above, all end-user subnets are to be of size /64. This is a recognized standard subnet size that allows for a nearly limitless number of hosts, optional host autoconfiguration, and maximum compatibility.

In special circumstances, it may be useful to use /112 for point-to-point links or for private, unique application uses such as cluster heart-beat links. The /112 size is not officially standardized, but is somewhat recognized to be used for these situations. You should check beforehand to make sure it will work for your specific application.

Reserve allocations

In the interest of sustaining long-term growth, as each allocation is made a corresponding allocation will be held in reserve. In the event that an existing allocation is too small, the reserve space may be used to accommodate growth.

Requesting an allocation

Contact the DoIT helpdesk to request an IPv6 allocation.