case study 07 / 09Win-Stone Campus · Networking · 2024

Multi-Building Campus Network

A new building 100 m away needed to join the campus network, but cable couldn't cross the private land in between and there was no budget for enterprise gear.

Split a campus network into subnets on basic ISP routers and unmanaged switches, then joined a building 100 m away over a wireless bridge, so all four buildings and their ~60 CCTV cameras ran on one network.

~100 M · NO CABLEMAIN × 3NEWONE NETWORK
buildings on one network
4buildings on one network
wireless bridge instead of cable
~100 mwireless bridge instead of cable
subnets: classrooms, admin, management
3subnets: classrooms, admin, management
CCTV cameras viewable from one office
~60CCTV cameras viewable from one office

01The situation

The campus had three main buildings already sharing one flat network. The IT lab was the exception: an isolated network of 30+ computers managed by Windows Server 2019, which I set up separately.

The equipment was basic: two standard-issue ISP routers (Huawei), unmanaged switches and hubs, and Ruijie access points. There was no budget for managed switches or enterprise gear.

Later the campus added a fourth building about 100 m away, with its own ISP router and switches. The ISP couldn't run cable to it, because the route crossed private property, so it would have been a separate island with its own internet line and its own cameras.

02What it had to do

  • Separate classroom, admin and management traffic on the existing equipment.
  • Bring the new building onto the main network without a cable between the buildings.
  • Let the CCTV in every building be viewed from one place: about 60 cameras, with an NVR in each building.
  • Work within the equipment the campus already had.

03Architecture

  1. Main buildings (three)

    • ISP routers

      Two standard-issue Huawei routers: the campus gateway to the internet.

    • Switching

      Unmanaged switches and hubs carrying the building network.

    • Wi-Fi

      Ruijie access points.

    • Subnets

      Classrooms, admin and management on separate subnets.

    Downward link: Ruijie point-to-point wireless bridge, ~100 m, about 100 Mbps in use

  2. New building

    • ISP router, repurposed

      Reconfigured to act as a repeater and switch, so it stops being a separate network and extends the main one.

    • Switches, cameras and NVR

      Local devices and the building's CCTV recorder, now on the campus network.

One network across all four buildings, so each building's NVR can be reached from an office in the main building.

I did the network; the CCTV system itself was installed by others.

The IT lab stays on its own isolated network, managed by Windows Server 2019.

04How it works

  1. Segment

    Split the network into separate subnets for classrooms, admin and management, configured on the routers and access points, so each group's traffic is kept apart on the same physical network.

  2. Bridge

    With cable ruled out, I proposed a point-to-point wireless bridge between the main buildings and the new one, about 100 m apart. A pair of Ruijie bridge units carries the campus network across the gap as if it were a cable, at about 100 Mbps in day-to-day use.

  3. Repurpose the router

    Instead of letting the new building's ISP router run its own separate network, I reconfigured it to act as a repeater and switch. Devices in the new building take part in the main network through the bridge.

  4. Centralise

    Each building has its own CCTV recorder (NVR), about 60 cameras in all. With all four buildings on one network, every NVR can be reached from an office in the main building, so the whole campus is watched from one place.

05What changed

  • All four buildings run on one centrally managed network instead of two separate ones.
  • About 60 cameras across four buildings are monitored from one office in the main building.
  • Classroom, admin and management traffic are segmented, on the same basic equipment the campus already had.

06Takeaways

  • A constraint like "no cable" or "no budget" changes the design, not the goal: a wireless link and a repurposed router reached the same result as new cabling.