Network storage device types and application features
Before stepping into the topic, we need to clarify the types of network monitoring storage devices at this stage and their application characteristics in network monitoring. At present, the storage devices come in different solutions depending on the organization mode and the network nodes, and can be roughly divided into three types of digital video recorders (DVRs), direct attached storage devices (DASs), and network attached storage devices (NASs).
Digital Video Recorder (DVR)
The stand-alone digital video recorder DVR is the simplest and most economical way to operate a high-quality digital video surveillance system. It is not only slim and fit, but also very lightweight, just add a camera to normal operation.
DVR is best suited for managing complex network monitoring solutions without the need for resources. Because the DVR system is usually easy to use and operate, on-site operators can easily view video stored video, and perform routine maintenance and data management at any time. In addition, it is also the device with the lowest node content limit on the network installation.
Direct Connected Storage (DAS)
As the name suggests, the DAS links the storage device directly to the DVR or NDVR. It can be internally attached (the disk drive is mounted inside the DVR), and it can also be connected externally via SCSI, USB, or eSATA adapters via multiple RAID external array storage interconnects. Although the cost is high, and the RAID disk array is cumbersome and bulky, the DVR that the external DAS can provide only has the capacity of storage and expansion. At the same time, the external DAS chassis also facilitates the provision of disk drive slots that are higher than the DVR built-in disk bays. If you need more disk drives, the external DAS chassis can be used to increase the available storage capacity. It should be noted that this type of storage network configuration node also allows users to access video recording via the network TCP/IP architecture.
Network Attached Storage (NAS)
The NAS resembles a mini-web server. It generally helps files to be stored on the Ethernet network through TCP/IP, and uses the common NFS or CIFS file-level communication protocol. NAS deployment and maintenance use common IP and Ethernet communication protocols. Only a few IT staff can manage NAS. Like the external DAS chassis, the NAS includes multiple disk drive bays that allow the user to select the RAID drive configuration that best balances performance, capacity, and fault tolerance. Even if more capacity is required, the NAS can be implemented by adding an external storage device module. Objectively speaking, this kind of equipment is particularly vivid in the layout of network nodes.
After reviewing the above three current mainstream network storage methods and architectures, there may be some new doubts in engineering implementation: In addition to the DVR is a very intuitive network node device on the network, others such as DAS, Where on the network are NAS and even SAN storage devices? How are these network storage devices arranged in the installation process?
Before understanding the placement of video storage devices, familiarize yourself with the network environment in which storage devices are placed, that is, how the network architecture topology is set.
Network node architecture characteristics that determine the storage location
The network topology can also be defined as a network architecture. The topology definition consists of two parts: the physical topology is the actual layout of the cable (media); the other is the logical topology is to define how the host accesses the media. The general physical topology used is bus, ring, star, extended star, hierarchical and mesh. These network architectures exist in various video surveillance network environments. Therefore, it is necessary for us to have a prior understanding and understanding of these various modes that determine the architecture of network nodes before the project is implemented. Next, one by one to recognize and understand their decision-making relationship in the location of video equipment. These common architectures are as follows.
Star schema
This network architecture is the simplest and most reliable. Network monitoring workstations (Clients) and recording devices (DVRs, NVRs, DAS...) are centrally connected to LAN hubs, and any one host can quickly isolate the problem without affecting the operation of other network devices and the entire network. Because the architecture is simple and easy to maintain and manage, "star shape" is the most used network architecture for business and security monitoring. The HUB in this architecture will connect all nodes (devices) of the network to transfer network signals. HUB has a large number of brands, with 4, 8, 12, 16, and 24 in the majority. The so-called port is the signal entry or delivery point, similar to the video and control data access points mentioned in the monitoring network protocol layer. At present, HUB's technology has been developed to provide a switching hub (switching HUB) with a speed of over 150 Mbps. With this hub, a star topology can be successfully completed, and video storage devices can be placed on any node of the architecture.
There is also an extended star topology. In fact, the so-called extended star topology is to connect the star topology topology of switching hubs/switches into a single small star topology. In this way, engineers can extend the length and size of the monitoring network according to the actual needs of the project, or expand the placement nodes of network video storage devices. The extended star topology is a repeating star topology, except that each node that is connected to the central node is also the center of another star structure. Physical point of view: The extended star topology has a core star topology, and the end nodes of each core topology are the centers of their own star topology. This structure has the advantage of shortening the wiring and limiting the number of devices that need to be connected to any one of the central nodes.
Ring architecture
The ring architecture connects the monitoring host workstation and the storage device host (DVR, NVR...) to Rings using different switching hubs, through so-called network tokens or graphic loop networks. To determine which monitoring host workstations have network management rights. This kind of framework is the standard that IEEE sets, namely TokenBus mark graphic bus line of IEEE802.4 and IEEE802.5 label ring (TokenRing) Network. This kind of monitoring network environment usually has some monitoring frameworks that are more concerned with network security. However, in this architecture, storage video equipment is more commonly found on such network nodes.
The ring network frame also has an extension, which is a dual-ring topology. The dual-ring topology consists of two concentric rings in view of the monitoring network. Each ring is only connected to its adjacent ring adjacency. The two rings are not connected together. It actually looks like the dual-ring topology is the same as the single-ring topology except that there is a second duplicated ring that is used to connect the same device. In other words, in order to provide the reliability and flexibility of the monitoring and storage network, each network device is also part of two independent ring topologies. This is also a perspective of the use of alternative networks.
Bus architecture
The bus architecture is also a kind of BUS architecture, but it uses a network coaxial cable to connect various location monitoring or computer hosts into a network system.
Its main drawback is the reliability of the network, which is relatively rare in network monitoring. The bus topology is a single backbone network segment that allows all network monitoring devices to connect directly. The bus topology is to connect all nodes directly to one link with no other connections between the nodes. Both the monitoring host and the storage device are connected to a common line. In this topology, the primary device allows the host to join or catch a single shared media. One of the benefits of this topology is that all hosts are connected to each other and therefore can communicate directly; the downside is that if one of the hosts/workstations on the network fails or the cable is broken, or the network is connected Damaged devices and connectors will cause the entire network to crash. The bus topology allows all network monitoring devices to see the video storage device's signals and send all the video information to all monitoring host devices; however, the problems caused by this can not be ignored, because traffic and network congestion often occur.
Hierarchical topologies are made in a manner similar to an extended star topology, which does not link hubs/switches together, but instead connects to computers that control topology data traffic. Mathematical point of view: The tree topology is similar to the extended star topology. The main difference is that instead of using a central node, it uses a trunk node, which branches to other nodes. There are two tree topologies: a binary tree structure (each node is divided into two links); and a trunk tree structure (the trunk network trunk has branch nodes, and the links are distributed on the branches). Physical point of view: The trunk is a cable that contains several branches. Logical point of view: Information flow is hierarchical.
Mesh architecture
The mesh topology is suitable for industrial projects that require extremely stringent network communication requirements, such as road monitoring control systems. You can see that each monitoring host is connected to all other hosts. This also reflects the Internet's design characteristics, the Internet has multiple path to any position. Mathematical point of view: In a complete mesh topology, each node is directly connected to other nodes, that is, each recording device is linked to each monitoring station. The advantages of this wiring method are numerous and the disadvantages are also very obvious. The advantage is that since each node is actually connected to other nodes, causing duplicate connections, video information can still be delivered to destinations through any other link if any link failures are not available. And this topology allows image information to flow along multiple channels throughout the entire network; the disadvantage is that as long as there are more than a few cameras or monitoring workstations and DVR nodes, the amount of media in the link can easily be too large for the network to bear. .
Irregular network topology
This irregular topology is also less common in the video equipment node architecture of surveillance systems. The reason is that in an irregular network topology, there are no obvious patterns between links and nodes, and there is a lack of a unified wiring pattern; there are various Different wiring patterns are pulled by the node. This kind of cabling structure is usually the stage that the network is still in the early stage of architecture, or the poor planning of the network architecture.
Honeycomb network topology
This type of architecture is mostly used in wireless point network architectures. It is more complex to consider the storage node placement. The honeycomb topology network architecture consists of round or hexagonal areas, each of which has a node in its center. The honeycomb topology is to divide the geographical area into regions (cells) for use by wireless technology. The importance of this technology is increasing. There is no physical network line link in the cellular topology, only electromagnetic waves, so the node is sometimes referred to as a receiving node, and sometimes becomes a transmitting node. The cellular network topology is not highly confidential and can be easily intercepted and interfered. Therefore, in the monitoring project, this type of architecture is also relatively rare.
The term topology structure can be seen as "the study of nodes." In fact, topology network architecture consists of nodes (points) and links (lines), and there are often fixed patterns between the two. From a monitoring point of view, it illustrates the topological architecture of video recording equipment that can operate on the network.
And then from the physical network is to see how to build video and monitoring equipment line. Finally, in engineering, we must use the logical topology to learn video or control the flow of information through the network, to determine the areas where network traffic may collide. A monitoring network is likely to apply a physical topology, but in reality it does not comply with the topology architecture logic.
Node switching equipment is also the key to video equipment placement
In addition to the above types of storage devices and network architecture topologies, there is a decisive factor in network recording equipment placed on the network monitoring equipment. There are unspoken rules for relays in general Ethernet: no more than four repeaters or relay hubs can appear between any two workstations or computers on the network. Because each additional relay station will increase the delay of data transmission, it will cause the monitoring picture to be delayed and the data signal strength will slow down. This caused an "accident" such as a video drop or a crash of the surveillance control server. Many monitoring companies have chosen to ignore this principle when constructing a network, or they have not noticed the key impact when building a monitoring system in an existing network environment. Four rule factors beyond the repeater may cause a violation. Maximum delay limit. When this delay limit is exceeded, the number of delayed collisions increases. Therefore, the placement of the recording device in such a network environment becomes more important.
Conclusion <br> <br> video equipment is the soul of network monitoring, all monitoring results and the purpose is to record the video evidence of the final save. With the increasing complexity of the network environment, how to carefully consider the placement of recording equipment in the network during construction has become an indispensable common sense for the contractor. It is also the key to the success or failure of the monitoring system. We hope to share advanced engineering with advanced statements.
Before stepping into the topic, we need to clarify the types of network monitoring storage devices at this stage and their application characteristics in network monitoring. At present, the storage devices come in different solutions depending on the organization mode and the network nodes, and can be roughly divided into three types of digital video recorders (DVRs), direct attached storage devices (DASs), and network attached storage devices (NASs).
Digital Video Recorder (DVR)
The stand-alone digital video recorder DVR is the simplest and most economical way to operate a high-quality digital video surveillance system. It is not only slim and fit, but also very lightweight, just add a camera to normal operation.
DVR is best suited for managing complex network monitoring solutions without the need for resources. Because the DVR system is usually easy to use and operate, on-site operators can easily view video stored video, and perform routine maintenance and data management at any time. In addition, it is also the device with the lowest node content limit on the network installation.
Direct Connected Storage (DAS)
As the name suggests, the DAS links the storage device directly to the DVR or NDVR. It can be internally attached (the disk drive is mounted inside the DVR), and it can also be connected externally via SCSI, USB, or eSATA adapters via multiple RAID external array storage interconnects. Although the cost is high, and the RAID disk array is cumbersome and bulky, the DVR that the external DAS can provide only has the capacity of storage and expansion. At the same time, the external DAS chassis also facilitates the provision of disk drive slots that are higher than the DVR built-in disk bays. If you need more disk drives, the external DAS chassis can be used to increase the available storage capacity. It should be noted that this type of storage network configuration node also allows users to access video recording via the network TCP/IP architecture.
Network Attached Storage (NAS)
The NAS resembles a mini-web server. It generally helps files to be stored on the Ethernet network through TCP/IP, and uses the common NFS or CIFS file-level communication protocol. NAS deployment and maintenance use common IP and Ethernet communication protocols. Only a few IT staff can manage NAS. Like the external DAS chassis, the NAS includes multiple disk drive bays that allow the user to select the RAID drive configuration that best balances performance, capacity, and fault tolerance. Even if more capacity is required, the NAS can be implemented by adding an external storage device module. Objectively speaking, this kind of equipment is particularly vivid in the layout of network nodes.
After reviewing the above three current mainstream network storage methods and architectures, there may be some new doubts in engineering implementation: In addition to the DVR is a very intuitive network node device on the network, others such as DAS, Where on the network are NAS and even SAN storage devices? How are these network storage devices arranged in the installation process?
Before understanding the placement of video storage devices, familiarize yourself with the network environment in which storage devices are placed, that is, how the network architecture topology is set.
Network node architecture characteristics that determine the storage location
The network topology can also be defined as a network architecture. The topology definition consists of two parts: the physical topology is the actual layout of the cable (media); the other is the logical topology is to define how the host accesses the media. The general physical topology used is bus, ring, star, extended star, hierarchical and mesh. These network architectures exist in various video surveillance network environments. Therefore, it is necessary for us to have a prior understanding and understanding of these various modes that determine the architecture of network nodes before the project is implemented. Next, one by one to recognize and understand their decision-making relationship in the location of video equipment. These common architectures are as follows.
Star schema
This network architecture is the simplest and most reliable. Network monitoring workstations (Clients) and recording devices (DVRs, NVRs, DAS...) are centrally connected to LAN hubs, and any one host can quickly isolate the problem without affecting the operation of other network devices and the entire network. Because the architecture is simple and easy to maintain and manage, "star shape" is the most used network architecture for business and security monitoring. The HUB in this architecture will connect all nodes (devices) of the network to transfer network signals. HUB has a large number of brands, with 4, 8, 12, 16, and 24 in the majority. The so-called port is the signal entry or delivery point, similar to the video and control data access points mentioned in the monitoring network protocol layer. At present, HUB's technology has been developed to provide a switching hub (switching HUB) with a speed of over 150 Mbps. With this hub, a star topology can be successfully completed, and video storage devices can be placed on any node of the architecture.
There is also an extended star topology. In fact, the so-called extended star topology is to connect the star topology topology of switching hubs/switches into a single small star topology. In this way, engineers can extend the length and size of the monitoring network according to the actual needs of the project, or expand the placement nodes of network video storage devices. The extended star topology is a repeating star topology, except that each node that is connected to the central node is also the center of another star structure. Physical point of view: The extended star topology has a core star topology, and the end nodes of each core topology are the centers of their own star topology. This structure has the advantage of shortening the wiring and limiting the number of devices that need to be connected to any one of the central nodes.
Ring architecture
The ring architecture connects the monitoring host workstation and the storage device host (DVR, NVR...) to Rings using different switching hubs, through so-called network tokens or graphic loop networks. To determine which monitoring host workstations have network management rights. This kind of framework is the standard that IEEE sets, namely TokenBus mark graphic bus line of IEEE802.4 and IEEE802.5 label ring (TokenRing) Network. This kind of monitoring network environment usually has some monitoring frameworks that are more concerned with network security. However, in this architecture, storage video equipment is more commonly found on such network nodes.
The ring network frame also has an extension, which is a dual-ring topology. The dual-ring topology consists of two concentric rings in view of the monitoring network. Each ring is only connected to its adjacent ring adjacency. The two rings are not connected together. It actually looks like the dual-ring topology is the same as the single-ring topology except that there is a second duplicated ring that is used to connect the same device. In other words, in order to provide the reliability and flexibility of the monitoring and storage network, each network device is also part of two independent ring topologies. This is also a perspective of the use of alternative networks.
Bus architecture
The bus architecture is also a kind of BUS architecture, but it uses a network coaxial cable to connect various location monitoring or computer hosts into a network system.
Its main drawback is the reliability of the network, which is relatively rare in network monitoring. The bus topology is a single backbone network segment that allows all network monitoring devices to connect directly. The bus topology is to connect all nodes directly to one link with no other connections between the nodes. Both the monitoring host and the storage device are connected to a common line. In this topology, the primary device allows the host to join or catch a single shared media. One of the benefits of this topology is that all hosts are connected to each other and therefore can communicate directly; the downside is that if one of the hosts/workstations on the network fails or the cable is broken, or the network is connected Damaged devices and connectors will cause the entire network to crash. The bus topology allows all network monitoring devices to see the video storage device's signals and send all the video information to all monitoring host devices; however, the problems caused by this can not be ignored, because traffic and network congestion often occur.
Hierarchical topologies are made in a manner similar to an extended star topology, which does not link hubs/switches together, but instead connects to computers that control topology data traffic. Mathematical point of view: The tree topology is similar to the extended star topology. The main difference is that instead of using a central node, it uses a trunk node, which branches to other nodes. There are two tree topologies: a binary tree structure (each node is divided into two links); and a trunk tree structure (the trunk network trunk has branch nodes, and the links are distributed on the branches). Physical point of view: The trunk is a cable that contains several branches. Logical point of view: Information flow is hierarchical.
Mesh architecture
The mesh topology is suitable for industrial projects that require extremely stringent network communication requirements, such as road monitoring control systems. You can see that each monitoring host is connected to all other hosts. This also reflects the Internet's design characteristics, the Internet has multiple path to any position. Mathematical point of view: In a complete mesh topology, each node is directly connected to other nodes, that is, each recording device is linked to each monitoring station. The advantages of this wiring method are numerous and the disadvantages are also very obvious. The advantage is that since each node is actually connected to other nodes, causing duplicate connections, video information can still be delivered to destinations through any other link if any link failures are not available. And this topology allows image information to flow along multiple channels throughout the entire network; the disadvantage is that as long as there are more than a few cameras or monitoring workstations and DVR nodes, the amount of media in the link can easily be too large for the network to bear. .
Irregular network topology
This irregular topology is also less common in the video equipment node architecture of surveillance systems. The reason is that in an irregular network topology, there are no obvious patterns between links and nodes, and there is a lack of a unified wiring pattern; there are various Different wiring patterns are pulled by the node. This kind of cabling structure is usually the stage that the network is still in the early stage of architecture, or the poor planning of the network architecture.
Honeycomb network topology
This type of architecture is mostly used in wireless point network architectures. It is more complex to consider the storage node placement. The honeycomb topology network architecture consists of round or hexagonal areas, each of which has a node in its center. The honeycomb topology is to divide the geographical area into regions (cells) for use by wireless technology. The importance of this technology is increasing. There is no physical network line link in the cellular topology, only electromagnetic waves, so the node is sometimes referred to as a receiving node, and sometimes becomes a transmitting node. The cellular network topology is not highly confidential and can be easily intercepted and interfered. Therefore, in the monitoring project, this type of architecture is also relatively rare.
The term topology structure can be seen as "the study of nodes." In fact, topology network architecture consists of nodes (points) and links (lines), and there are often fixed patterns between the two. From a monitoring point of view, it illustrates the topological architecture of video recording equipment that can operate on the network.
And then from the physical network is to see how to build video and monitoring equipment line. Finally, in engineering, we must use the logical topology to learn video or control the flow of information through the network, to determine the areas where network traffic may collide. A monitoring network is likely to apply a physical topology, but in reality it does not comply with the topology architecture logic.
Node switching equipment is also the key to video equipment placement
In addition to the above types of storage devices and network architecture topologies, there is a decisive factor in network recording equipment placed on the network monitoring equipment. There are unspoken rules for relays in general Ethernet: no more than four repeaters or relay hubs can appear between any two workstations or computers on the network. Because each additional relay station will increase the delay of data transmission, it will cause the monitoring picture to be delayed and the data signal strength will slow down. This caused an "accident" such as a video drop or a crash of the surveillance control server. Many monitoring companies have chosen to ignore this principle when constructing a network, or they have not noticed the key impact when building a monitoring system in an existing network environment. Four rule factors beyond the repeater may cause a violation. Maximum delay limit. When this delay limit is exceeded, the number of delayed collisions increases. Therefore, the placement of the recording device in such a network environment becomes more important.
Conclusion <br> <br> video equipment is the soul of network monitoring, all monitoring results and the purpose is to record the video evidence of the final save. With the increasing complexity of the network environment, how to carefully consider the placement of recording equipment in the network during construction has become an indispensable common sense for the contractor. It is also the key to the success or failure of the monitoring system. We hope to share advanced engineering with advanced statements.
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