How to design an IP network to carry surveillance traffic in large multi-building apartment complexes ?

Generally, every apartment should have some mechanisms like cable trays or raceways to interconnect all buildings for both internet and power. And we recommend that those be used to create the cabling infrastructure. This would essentially be a Wired Ethernet LAN built using Smart switches in a hierarchical fashion as Cisco outlines in their design philosophy by using horizontal layers like Access (10/100 mbps PoE with Gigabit uplinks at a bare minimum), Distribution (10/100/1000 mbps non-PoE) and Core (1G-10G non-PoE)

For smaller project setups such layering and smart switching maybe an overkill, but for large setups they should be used to ensure stability, maintainability, reliability and extensibility. Unfortunately many system integrators use crude methods like:

(1) Daisy chained switches instead of connecting them in Hub-Spoke fashion
(2) random mixture of fiber and copper links based on cable length required to nearest daisy chain link

to skimp on labor effort & costs, and end up delivering a very bad IP networking system, because they have not paid any attention to link capacity and load (very uneven links), progressive switching delays, reliability impact if one switch goes down, etc. 

Please also note that low voltage cat 5e/6 cables should never be run in conduits parallel to electrical lines (they pose both safety - high voltage getting onto low voltage lines in case of rat bite or other accident triggered short circuits AND electromagnetic interference problems) in raceways/trays/walls/ceilings, but its safe to run Optical fiber cables.

In the rare scenario that their are no raceways/cable-trays available because the builder did not install them, you may have to do so OR use wireless PtP/PtMP links over buildings to create a backbone IP network as shown below:

The main requirement for the above is line of sight and each link is constrained by the speed of wireless links. It may work for a moderate number of cameras, but will definitely not scale up [200-500 mbps may be the maximum link speed] to accommodate more applications. nevertheless they may be the only networking choice if both wired and cellular are not practical. This type of setup can also be used to augment an otherwise proper wired networking setup in case their are certain areas to which cabling is not feasible (still they have to get power somehow).

- Suman Kumar Luthra @ APRC-P3 Telecom Sub-Committee