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Introduction to Network Video Security

The video security industry has been in the process of transition from a mechanical, analog system of video recorded on VCR (Video Cassette Recorder) tapes to dynamic, digitized system of video stored on a network. The first stage of this evolution was the replacement of the VCR by the DVR (Digital Video Recorder). The cameras were still analog but the storage device was digital.

Introduction to Network Video Security

The video security industry has been in the process of transitioning from a mechanical,
analog system of video recorded on VCR (Video Cassette Recorder) tapes to a dynamic,
digitized system of video stored on a network. The first stage of this evolution was the
replacement of the VCR by the DVR (Digital Video Recorder). The cameras were still
analog but the storage device was digital.

The DVR introduced video stored to hard disk rather than individual VCR tapes or magnetic
tape libraries. This reduced the footprint of the video storage system in many large
corporations that were using tape libraries or carousels. With the DVR came many benefits of
digitized data to the security industry such as better video compression algorithms, increased
video quality, dynamic video searching, increased storage capacity resulting in longer
retention of video, concurrent real-time viewing and playback capability, decentralized
viewing from anywhere on the network, and best of all, no one had to change the VCR
tapes. A Network Video Recorder or NVR is an internet protocol based device that sits on
your network. With the ability to record IP and analog cameras, DVRs and NVRs (Network
Video Recorders) offer freedom of choice in security networks design and configuration,
while protecting the investments made in current infrastructure.

Disk Systems
The key factor in any video security system is reliability. Disk technology has evolved over
the past decade and become very stable. VCR tapes could store a limited amount of video,
although the quality would degrade over time. DVR and NVR system hard drives can reliably
store days of video as opposed to hours (For VCRs) depending on the video resolution
and compression algorithm. A DVR or NVR with an attached RAID (Redundant Array of
Independent Disks) increases storage capacity by combining multiple hard drives in a single
chassis resulting in a mass storage system.

Security systems start with recording video and end with playback. If the storage in a
video security system fails, the entire system fails. This is why the security industry has
implemented RAID as a standard component in the security system. RAID systems have
features that can include dynamic hot swappable drives, scan/recovery capabilities,
hot spare drives in the chassis, and redundancy.


Real-Time Storage and Archive
Storage systems comprise of more than just the hard drives. NAS (Network Attached
Storage) uses the flexibility of the network to make high capacity storage available
directly from the network. An alternative technology of SAN (Storage Area Networks)
attaches high capacity storage to its own dedicated high speed network, access to which
is gained through a server. The impact of the additional parts of the storage system must
be considered when assessing their suitability for video security storage. These storage
systems have evolved as a result of the needs of data applications. The needs of a video
security storage system are somewhat different.

In a typical data system access to the storage is sporadic and consists of typically 50%
write access and 50% read access with total utilization being perhaps less than 50%. In
a video system the volumes of data are significantly higher and the read/write cycles are
very different with often 100% write and very sporadic read. However when read access is
required it often needs very rapid access to significant amounts of data without excessive
search times which will disrupt the displayed video. In addition security systems often need
access to data almost as soon as it was written. Some RAID technologies help significantly in
improving read/write access times as well as enhancing reliability, but applying this through
NAS or SAN connections can cause limitations in throughput and search times that cannot
sustain video security systems.

In reality DVRs and NVRs are primarily very specialized storage systems that can record
and replay the vast amounts of data within the very critical constraints of a real-time
security system.

There are clear financial and management benefits in having a large storage farm used
for many applications – parallels to the benefits of sharing the network between many
applications. However this must be assessed against the over-riding criteria of a new security
system – does it enhance your security? There are three ways of sharing storage farms while
still maintaining appropriate performance from the security system.
1. Limiting the use of any shared NAS/SAN to fit within the security performance criteria,
and giving priority to video. This approach may remove any financial benefit from using
a shared resource.
2. Using a dedicated NAS/SAN that performs within the required criteria.
3. Using dedicated storage within the DVR/NVR for a limited period – perhaps 5 days – and
then archiving older video to a NAS/SAN.


This last option gives the benefits of high speed and reliable access to recent video while
taking advantage of the cost savings by using a storage farm for the video that is not needed
for instant access.

The issues surrounding video storage technologies and storage capacity are the fragility of
the drive system. Hard drives are very susceptible to environmental influence. Heat, dust,
and vibration are all factors that can cause a hard drive to fail.
NAS (Network Attached Storage) and SAN (Storage Area Network) technologies can address
some of these issues but at a much higher cost. NAS is a specialized storage device (or
group of devices) that attach to the network and provide fault tolerant, centralized network
storage, which is easily expandable without reconfiguring the existing storage. The primary
difference between a NAS and RAID storage system is that NAS interfaces directly with the
network while RAID storage requires a device/server to which it is attached. This device/
server attaches directly to the network. NAS has only one function, to store and retrieve data,
and is faster because it has reduced latency due in part to the direct network connection. The
network clients request data stored on a NAS device through their network file server.

SAN networks are very expensive but if your industry has high compliance requirements, this
may be the best system to implement. Banks, hospitals, resorts, government agencies and
large enterprise networks use Storage Area Networks to protect the integrity and availability
of their data. SAN networks are based on a fiber channel architecture that is extremely fast,
operating at transmission speeds of 1Gbps or higher. All components in a SAN are fully fault-
tolerant, guaranteeing the availability of the data even if a component of the SAN fails.
As with any well-designed distributed network, any SAN device has a communication
path to all other devices on the network similar to a mesh topology. That is the greatest
benefit of an IP-based, converged network. All IP-based traffic utilizes the same physical
network infrastructure, leveraging the cost of cable plant, network storage, and IT staff.
Digital solutions cost more initially and require a much higher level of expertise to design,
implement, and maintain the integrity of the network.
The return on investment is the flexibility, scalability, security, and fault-tolerance of the
design. If surveillance history is a requirement of your industry, then an IP network solution
is the most cost effective solution over time.


Quality of Service
Quality of Service (QoS) provides a software-based ability to guarantee the required
level of network resources for priority or real-time traffic. QoS is a major performance
factor for network administrators as a growing number of non-traditional devices
are deployed on the network such as phones, cameras, access control, and building
environmental or security systems. QoS provides the ability to control access to available
network resources, reserving bandwidth for specific traffic. A delay in the transmission
to lower the current temperature of a room to a network-based HVAC system is not as
critical as real-time video streams from a security camera or the voice traffic of an IP
phone system.
The network administrator can prioritize the traffic types by service (known as
Differentiated Service (DiffServ)), each of which requires different levels of access
to network resources. With significantly varied types of services being delivered on
the network, it is no longer feasible to rely upon First-In-First-Out (FIFO) technology.
In a network that supports IP based video security, every switch that transmits the
video traffic should be capable of implementing QoS, not only to provide a guaranteed
throughput for the video, but to allocate bandwidth for all other services on the network.
Without QoS, network performance could suffer from the impact of constant streams
of IP video degrading the overall network performance, while other services no longer
receive their required minimum level of resources.

An analog camera transmission is always unsecured. An IP camera attached to the network
as an independent node transmitting network based video can be secured end-to-end.
This is a prevailing network best practice for transmitting sensitive data using open source
protocols. Many of the features that can enhance the security of a video security network
are current best practices in the data network world. IT technologies have standards and
practices that can be transparently applied to video transmitted from an IP camera that
supports those protocols and applications.
Helping the world’s businesses keep their buildings, employees, and customers safe
and secure is a fast-growing industry. The key security control systems in use today
are intrusion detection, access control, and video surveillance. If each of these systems
is managed separately, training, maintenance, and administration could become an
expensive burden to a company.
Integrated IP network systems are quickly taking over this market because they reduce
costs, simplify access and delivery, leverage existing infrastructure, and improve the overall
security of physical and logical property. IP-based security enables businesses to broaden
their security objectives by providing a single user interface into all physical structures.
IP-based security solutions support the ability to manage all facilities and remote
sites from a single computer, anytime, anywhere. An IP-based control environment supports
centralized administration which provides flexibility, programmability, and reduced
complexity, which in itself, increases security overall.
The meaning of “state of the art” security is changing from a collection of separate processes
and devices aimed at guarding facilities or intellectual property to becoming a convergent
technology. The integration of security systems, building management systems, and IT
systems, increase return on investment by providing a solution at the application level.

CREDITS: This article was published on Pelco Press.