For *small home/enterprise installations, physical deployment area is small. Any regular unmanaged switch of 4/8/16/24/48 port capacity based on the number of cameras needed would suffice. Its simple, will work reliably and if their is a problem, it can be restarted. We do not think such installations would even need PoE extension features (use for upto 250m cable instead of the regular 100m). Generally their is only one hop in LAN (i.e camera device and one/two recorder connected directly to one switch). And switches can frequently be 10/100 fast ethernet instead of gigabit ethernet or better.
However, when handling large installations, scale complexities arise
(a) Cable lengths of some camera points may increase beyond 100m in corner cases. A switch with PoE extension feature is a nice add on.
(b) Their is more risk of lightning strikes as more outdoor devices could be present and Ethernet port surge protection may be nice to have feature.
(c) Instead of one switch you may need a network of interconnected switches often connected by OFC links which are longer than 100m
(d) Their would be need to remote management equipment. Ability to hard reboot individual IP cameras by cycling power is at times useful in recovering from some faults (mostly IP Camera firmware related).
(e) The same network would likely need to support non-CCTV applications and different applications may need a logical isolation (VLAN)
(f) For large installations even though single camera bandwidth is 2-10 mbps, the aggregated bandwidth on some link(s) may exceed 1000 mbps and therefore require link aggregation.
Therefore from IP networking angle, VLANs, STP, Link aggregation, PoE On/Off, remote switch reboot are features that may be needed( and very useful) in large installations, but are totally absent in unmanaged switches.
Such large installations should use at least 10/100 *smart managed PoE switch with gigabit uplinks, Or better a *smart managed 10/100/1000 ethernet PoE switch. PoE Extend and Surge protection are highly desirable. An unmanaged switch can be used to augment the periphery but is better to avoid AFAP and definitely should not be used as a first choice. Unfortunately their is not much choice in smart PoE switches of less than 10 ports and they are also not value for money choice, with 24 port variations causing only a bit more, but much more expensive than a small unmanaged 4/5/8 port PoE switch
Our network uses multiple applications and switch usage is 80% CCTV and 20% non CCTV and so we have initially deployed 10/100 smart web-managed switches which also support non-CCTV applications with an acceptable constraint of 100 mbps per port throughput. Few edge is supplemented by small unmanaged switches, which have given the occasionally physically rebooting job. The backbone is kept full Gigabit with link aggregation support and this system handles more than 450 IP Cameras and 100 Wifi access points. And their is enough room spare to grow for years with new applications like voice (intercom), building automation, etc.
- Suman Kumar Luthra @ APRC-P3 Telecom Sub-Committee
No comments:
Post a Comment