This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.
Power-over-Ethernet networks inject power to the LAN cable to power attached devices, which turns out to be handy for IP-based surveillance systems. The same LAN cable that carries the IP video traffic can power an IP camera up to 330 ft. away.
PoE switches fall into three basic categories: unmanaged, smart and managed." Unmanaged switches provide basic connectivity between networked devices at a low cost. However, they aren't capable of changing settings or functions. They tend to be easy to use and good for simple connectivity only." Smart switches have a Graphical User Interface (GUI) with easy-to-understand controls, and are managed via a web browser. They provide intuitive guidance to users and are ideal for those who have no advanced network training." Fully Managed switches have a GUI, and also a more technical Command Line Interface (CLI), which allows network administrators to create scripts to program and manage multiple switches. They support advanced networking features that are often beyond the needs of an IP surveillance network.
When designing an IP Surveillance network, it makes smart sense to step up from an unmanaged PoE switch to a Smart PoE switch. For just a small increase in cost, network administrators can gain significant added capabilities, tools and benefits for their surveillance networks.
Smart PoE switches, for example, feature an easy-to-use, browser-based user interface and straightforward communication. An administrator simply browses to the IP address of the switch, and then uses the intuitive GUI as a simple vehicle for configuring and monitoring important elements and features in the network.
With Smart switches, an administrator can remotely turn off/on the PoE power to each camera via the graphical user interface. This comes in especially handy when a camera needs to be rebooted. This action can be manually controlled at anytime from anywhere on the network, or over the Internet. The administrator need not be at the camera's location, nor be in the same room as the PoE switch, which avoids truck rolls, saves time and money.
Some Smart PoE switches also support Time-Based PoE--an option that allows administrators to set a time window that determines when each camera is powered off and on. This can be useful for networks that need to be shut down during certain times of the day, or for automatically scheduling IP camera reboots on a periodic basis with no manual intervention.
Network administrators often need to know the power consumption for each switch port and the overall PoE power budget utilization. Capturing this data simply isn't possible with an unmanaged switch. A Smart PoE switch, however, can provide the following power consumption statistics in real time:" Actual PoE power utilization per port" Total system PoE power budget" Amount of total PoE power currently being used" Amount of total PoE power still available
As the network grows and additional cameras are added, a PoE switch will be asked to supply more power. A Smart PoE switch allows an administrator to manage these increased power demands in a much more controlled manner, through user-defined port-priority assignments and policies.
A Virtual Local Area Network (VLAN) uses an Ethernet switch to partition a physical network, thereby creating distinct broadcast domains. VLANs are especially useful when an IP Surveillance network shares the same network infrastructure with other functions or applications, such as a corporate data network. By assigning the IP Surveillance traffic to a separate, distinct, high-priority VLAN, the traffic is assured to pass through the network swiftly and securely.
Some Smart PoE switches support a feature called Auto Surveillance VLAN, which simplifies VLAN configuration by automatically detecting any IP camera on the network. With no manual intervention, traffic from each camera is automatically assigned to a high-priority VLAN, which guarantees the quality and security of the surveillance information, even during periods of high network congestion.
Smart PoE switches enable administrators to easily examine the quality of the copper cables connected to each switch port. Tests can be initiated from anywhere on the network and run on each port during installation or troubleshooting to determine any potential cable errors. Diagnostics data includes:
" Cable connection: OK/Short Circuit/Open Circuit" Cable Fault Distance: If a cable fault is found, the test results will show the distance of the fault from the switch port" Cable Length: If test results show OK, they will also show the total length of the cable
Smart PoE switches may also feature a loop detection function, which can locate unintentional loops in a network. If a loop is detected, the switch automatically shuts down the port and alerts the administrator. Loop detection can be enabled on a single port, a range of ports or all ports simultaneously. Without such protection, undetected loops can wreak major havoc and cause serious traffic flow disruptions.
Unmanaged PoE switches don't have the ability to alert the network administrator after a change or disruption to the network. Smart switches, however, can send alerts to a network management system (typically SNMP-based) when such challenges arise. For example, a Smart PoE switch can send an alert to administrators when:" An Ethernet link goes up or down (e.g. an IP camera establishes or loses a link)" PoE power turns on/off for any port" A short circuit occurs on any port" A "Power Deny" action occurs on any port
In summary, while unmanaged PoE switches are considered a mainstay of IP surveillance networks because they are low-cost, easy-to-use and good for simple connectivity, more and more security professionals are realizing the tremendous benefits of upgrading to Smart PoE switches. The cost increase is minimal and these switches provide network administrators with a simple, easy-to-use interface through which the IP surveillance network can be configured and monitored from anywhere, anytime.
They also offer additional tools that enable administrators to enjoy faster network installation, easier network maintenance and upgrades, and better visibility into network health. It all adds up to time- and cost-savings that are attractive selling features for today's budget-conscious organizations.
D-Link is the global leader in connectivity for home, small business, mid- to large-sized enterprise environments, and service providers. An award-winning designer, developer, and manufacturer, D-Link implements and supports unified network solutions that integrate capabilities in switching, wireless, broadband, storage, IP Surveillance, and cloud-based network management.
Read more about wide area network in Network World's Wide Area Network section.
Join the CIO Australia group on LinkedIn. The group is open to CIOs, IT Directors, COOs, CTOs and senior IT managers.