This maintenance work can either be an upgrade to the networking component's operating system or a patch to an existing version of the operating system. These upgrades are tested ahead of time. The duration is relatively short and the impact to the local user community varies according to whether the equipment is a wiring closet, building entrance, or core routing device. Wiring closet devices are 24 to 48 port Ethernet switches. Building Entrance devices serve an entire building or group of buildings, and routing core devices serve many buildings or are the gateway routers in and out of PennNet.

ISC designs structured wiring to feed 3 floors of office space in most large buildings. In smaller buildings, wiring closets can feed half or as much as the entire building. As such, upgrades to wiring closets can affect various percentages of users in each building. ISC upgrades wiring closet devices every three years. These hardware upgrades take up to 4 hours per closet location and duration depends on the size and amount of wiring closet switches that are in each closet.The scope of the outage will be listed in the outage announcement.

Building Entrance (BE Devices) Serve all the wiring closets in an entire building or a group of small buildings. As such, upgrades to BE Routers will affect all users in the building. ISC upgrades BE devices every four years. These hardware upgrades take up to 2 hours per closet location and the duration depends on the size and amount of wiring closets that are in each building.The scope of the outage will be listed in the outage announcement.

The PennNet Core Routers are distributed among five Network Aggregation Points (NAP's) on campus. Each NAP serves roughly 20 to 25 percent of the campus buildings. Individual core routers connect all building entrance devices in its geographic area on campus. In addition, there are two gateway routers that provide redundant inbound and outbound connectivity to and from PennNet. Maintenance to the PennNet routing core can affect up to 40% of the user connections on PennNet. ISC is working to provide dual gigabit Ethernet links to each building such that core maintenance will have a significantly reduced impact to the user community. ISC upgrades Core devices every four years. These hardware upgrades take up to 2 hours per NAP location and the duration depends on the size and amount of buildings that are fed from each router. The scope of the outage will be listed in the outage announcement.