Campus IP Addressing
This document is a brief introduction to the various types of networks in use on and off campus. It is meant to provide a guideline for interpreting WiscNic output.
There are a number of networks which the American Registry for Internet Numbers (ARIN) has assigned to the University of Wisconsin-Madison and which are used for a variety of purposes. A complete listing of these networks can be found here: Campus IP Address Ranges.
When a WiscNic query uses an off-campus IP address, WiscNic will return "WHOLE-IPV4", which signifies that the network being queried is not a campus network. "WHOLE-IPV4" refers to the entire range of IP Version 4 networks possible, and only signifies that the network being queried is not one of the networks managed by the University.
Campus NetworksThere are two main types of Campus IP Networks: Customer and Network Management.
- Network Management
- Wireless: There are currently a number of networks assigned for wireless usage. These networks include both the wireless access points which the wireless hosts use to connect to the wireless LAN, as well as the wireless hosts themselves.
- Point-to-Point: Also referred to as "Layer 3 Overlay", these networks are used to provide IP connectivity between neighboring network devices and although they may be an indication of network problems, they sometimes can be down without any customer related outages.
- Management Networks: These networks are used to provide secure, direct management access to network devices. They allow network engineers to transfer data directly to the network devices and although they may be an indication of network problems, they can sometimes be down without any customer related outages.
- Loopbacks: These single IP address sized networks are assigned to individual network devices and should provide connectivity to the device any of its working connections. When the loopback of a device is down, this usually means the entire device is unreachable and there may be customer related outages.
These networks are assigned to campus departments and used for a variety of purposes, including assignment to end user machines or "hosts", typically workstations and servers used by Students, Faculty and Staff. All of these networks have departmental technical contacts associated with them, including the DoIT LAN networks. A reverse DNS lookup on customer network IP addreses will often return the departmental DNS name such as "doit.wisc.edu" or "athletics.wisc.edu".
These networks are used for a variety of network management purposes, including wireless access points, network hardware, and even networks used for network management. A reverse DNS lookup on a network management IP address will often return the network management DNS name "net.wisc.edu". There are a number of different kinds of network management networks:
Off-Campus NetworksThere are two main types of Off-Campus IP networks: Normal and Special Use.
- Special Use
There are a number of networks outlined in RFC 3330 which are defined as "Special Use" and are used for a variety of purposes. The following is a brief description of two types of commonly reported special use IP addresses:
- Private Use Networks: These networks are available for use for private networks and must be translated to a valid IP address to be routed outside of their own network. Obtaining one of these addresses from a customer does not give us any information about their network, we would need to know the translated IP address that appears as their source when seen from a remote network. Private use networks are outlined in more detail in RFC 1918 and should not appear on the public Internet.
- Link Local: Hosts obtain addresses in this range by auto-configuration, such as when a DHCP server may not be found. Typically we see addresses in this range on Windows clients when they are having network problems and only tells us that the host is unable to get a DHCP address. We need to know what IP address the customer should be receiving from the DHCP server.
These networks are assigned by ARIN to non-UW-Madison entities and their information can be found by performing a Whois query to a non-WiscNic Whois server.