IT Architecture Team Report:
Princeton University Network Architecture

The campus network is composed of three components: the physical network, the logical network, and network services.  The components interact to create the campus’s network infrastructure.

Physical network

The physical network consists of the hardware (internal building wiring, backbone fiber optics, building electronics, and core electronics) used to connect desktop computers with University servers and the Internet.  The design of the campus network is a classic Ethernet collapsed backbone.  The core electronics are located at 87 Prospect.  Fiber optic trunk cables extend from 87 Prospect to eleven fiber distribution locations (hub sites).  Fiber optic cables connect campus buildings to the hub site. 

About one square mile in size, the main campus contains approximately 100 academic and administrative buildings and 40 dormitories.  The University is in the process of upgrading the wiring network within campus buildings. A University database records the list of campus buildings and their local infrastructures.  Some buildings continue to use the older Cat 3 wiring.  Upgraded buildings use a Cat 5/fiber network infrastructure.

The internal network within a typical building has closet electronics that connect desktop computers to the building aggregation switch, which connects to the campus fiber backbone.  At the hub site, the building fiber connects to the backbone trunk in order to connect to the core electronics.  At the network core, high-speed switch-routers connect the building and dormitory networks with central servers and the Internet.

A number of campus locations have access to network services via the campus’s wireless network.  To use the wireless network, a client machine must have a wireless interface device. 

Remote access into the campus network is possible via dial-up modem or via a service such as DSL (Digital Subscriber Line) or cable modem.  The campus supports a virtual private network (VPN) service that permits off-campus hosts to gain access to restricted on-campus resources.

Logical network

The logical network defines how network data moves over the physical network infrastructure.  The campus network is based on the TCP/IP (Transmission

Control Protocol/Internet Protocol) protocol.  Other protocols such as AppleTalk and Netbios can make use of the available TCP/IP transport. The native Novell networking protocol, IPX (Internet Packet Exchange), is currently supported on the campus network, but is deprecated (A deprecated element or attribute is one that has been outdated by newer constructs).

The campus uses two Class B IP addresses: 128.112 for the academic and administrative network and 140.180 for the dormitory (Dormnet) network.  These blocks of IP addresses are organized into subnets.  Additional Class C IP addresses have been allocated to Princeton University to support special projects.

All devices attached to the campus network must be registered in the OIT Hostmaster database.  The Hostmaster registration process assigns a device a permanent IP address, updates network service files domain name service (DNS), dynamic host configuration protocol (DHCP), and Mobile IP, and provides information needed for host billing.

Network Services

Network services include: domain name service (DNS), which translates names into IP addresses; dynamic host configuration protocol (DHCP), which provides network configuration information to network-attached clients; and Mobile IP, which enables hosts to access network resources from various campus locations.

Additional information, including network utilization graphs, information on network charges, the Network Group’s mission and goals, and the operational status of the network resides on the Network Group’s website.