Eye on Video: Uptime for network video systems

Strategies for minimizing scheduled downtime


Short of catastrophic disaster, most networks today deliver between 99.99 percent and 99.9999 percent availability — from less than one hour of downtime a year to less than one minute of downtime a year. But even the most robust network needs downtime for component maintenance and system upgrades. The difference with video surveillance systems is that downtime can jeopardize public safety and compromise the security of assets, operations and facilities. While infinite redundancy would certainly solve the problem, such a strategy would be cost-prohibitive and impractical.

How do you address the challenge of designing your video surveillance system to minimize the risks of downtime? Different strategies apply for each system element — the network, the servers hosting the video management software, storage and the network cameras. Depending on the component, there are a number of best-practices options for maximizing availability.

The Network
Hot swaps and redundant power supplies on switches and other failover technologies are good options for the most critical components of the WAN or LAN. You can monitor these devices using tools ranging from simple bandwidth monitoring and generic Simple Network Management Protocol (SNMP) applications, to highly-sophisticated, detailed network traffic and packet analysis systems including custom Management Information Base (MIB-2) support.

You should install cabling, especially in multi-campus or exterior mounted nodes, with lightning protection and with proper termination. The main drop, for example, requires both a patch panel termination and a jack termination. For added protection, never directly terminate the cable between the switch and network camera. For easier maintenance, make sure your service loops are at least one foot at the network camera termination point.

Since the wide area network (WAN) supports mission-critical surveillance, you should design the core as a mesh network to provide multiple alternate paths in the event of a single path’s failure. A Multi-Protocol Label Switching–Virtual Private Network (MPLS-VPN), for example, delivers performance and privacy like a frame relay, combined with the flexibility and cost advantages of packet-based IP networks, like the Internet.

Plan and test any network changes prior to installation. Run patches and upgrades in the lab or on test equipment to ensure stability before introducing them to the production environment. Best practice is to always lag behind the latest service revision releases to prevent new issues from arising. When you perform maintenance, do so in localized phases so as not to create problems system-wide. With today’s robust technology, regular maintenance requirements are minimal but they are still essential for the continued health of the network.

Servers Hosting Video Management System
Many video management applications have built-in failover server capability for its server clusters. If the primary server detects a failure in one server, another identically configured server automatically takes over all the recordings of the cameras originally assigned to the failed server. It typically takes only seconds to switch servers and requires no operator/administrator intervention. This high level of failure protection is commonly used in mid-tier and enterprise video surveillance installations.

For the highest level of protection, you can send video from the network cameras to two different servers in separate locations simultaneously. Alternatively, the backup can be sent at a pre-determined time using a commonly supported archiving feature in the video management software. If you use WAN links during operating hours, you can back up video after hours to limit any disruption to other network applications using the WAN. These offsite servers can, in turn, be equipped with RAID, work in clusters or replicate its data with servers even further away.

Additional safeguards include component redundancy such as dual network interface cards and redundant hot swap power supplies. Network and database monitoring tools such as SNMP running on a network management system ensure data integrity and help maintain server health. Typically only the most mission-critical systems use health monitoring even in the largest of enterprises. Much like archived video, system support is mainly reactive to changing conditions, even if manufacturers provide tools to enable proactive management.

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