Network protocols used in IP video surveillance
IP-cameras use in their work a variety of network protocols required for transmitting video stream over the network, and for remote control of the camera. This article briefly describes the most commonly used network services and protocols in IP video surveillance.
The IPv4 - Internet Protocol the IP (of Internet Protocol) fourth version, first described in 1981 and today is the primary protocol, united by a local network to the global Internet network.
In IPv4, four-byte (32-bit) addresses are used (one byte is a decimal number from 0 to 255), so the IP address might look like this: 192.168.0.5. A significant disadvantage of the IPv4 protocol is the limited number of unique addresses 232 = 4,294,967,296, moreover, a number of other addresses are reserved for: networks of service providers, private networks and other service purposes. This forces the use of so-called dynamic IP addresses , that is, addresses that are provided to the client only for a certain time from the area of unoccupied addresses of a given subnet.
IPv6 is a new Internet protocol, released in 1996, with an increased address length of up to 128 bits, which will, according to various estimates, provide each inhabitant of the earth from 300 million to 5x10 28 unique addresses. In fact, such a large address space is made for hierarchical division, which will simplify routing, so much of the address will not be used at all.
IPv6 addresses are represented as eight groups of hexadecimal digits separated by colons, for example: 2000: 11a3: 13dc: 05fd: ff21: ccf2: 123f: 01ff.
Currently, IPv6 is not used significantly, in the future it is planned to share both IPv6 and IPv4 protocols to support legacy devices.
HTTP (HyperText Transfer Protocol) is a protocol for transferring hypertext using the client-server technology. The client, that is, the user's Internet browser, sends a request to the server as a URL (Uniform Resource Identifier) - a unique resource identifier and receives the requested WEB page from the server .
Hypertext - a specially formatted tex using the so-called the HTML (The HyperText Markup the Language - hypertext markup language) TEG s, which recognizes an Internet browser, for example of Internet Explorer . An example of formatting might look like this: <i> Hello Everyone! </ I> , which will be displayed in italics in the browser - Hello Everyone!
HTTPS (Hypertext Transfer Protocol Secure) - Modification of the HTTP protocol with the ability to encrypt data with SSL and TLScryptographic protocols . This protocol is used, for example, to authenticate users, transfer important documents in payment systems, etc.
FTP (File Transfer Protocol) is a file transfer protocol developed in 1971. It is used, for example, for uploading files to a server, downloading files from a server to a local computer, and similar tasks. Usually used with an FTP client , a program, usually with two windows, where dragging files and folders from one window to another, files are downloaded / unloaded.
TCP (Transmission Control Protocol) is a data transmission control protocol that checks the establishment of a network connection, sends a new request in case of packet loss, and does not allow duplicate packets. Thus, reliable data transmission is carried out with notification of the sending party about the quality of the transmission.
UDP (User Datagram Protocol) - a protocol for transmitting so-called “datagrams” - data blocks, without checking the success of the connection, packet loss and duplication, which significantly reduces the quality of data transmission. However, this approach is very useful in brief requests from a large number of clients to the server, such as in online games, which frees the server from waiting for packet integrity checks.
DNS (Domain Name System) is a domain name system that is responsible for matching IP addresses to host names. Typically used to determine the IP address by host name (by site name).
DHCP (Dynamic Host Configuration Protocol) is a protocol required for a computer to automatically obtain an IP address and other parameters necessary for normal network operation.
SMTP (Simple Mail Transfer Protocol) is a protocol for sending mail on the Internet, developed in 1982, and is used mainly for sending outgoing mail from a client program, for example, Outlook, to a mail server.
RTP (Real-time Transport Protocol) is a protocol for transmitting data in real time, with control of the sequence of packets and synchronization of data. This protocol is well suited for transmitting video and audio data over a network.
DynDNS is a service that allows a user with a dynamic IP address to get a subdomain (third-level domain name), with a static address to which the DynDNS service redirects the user's request.
Thus, a computer, IP camera, or any other network device works as if with a permanent IP address. A static IP address is required for network cameras to work .
NTP (Network Time Protocol) is a protocol designed to synchronize the internal clock of a computer with time services, for example, GLONASS.
RTSP (Real Time Streaming Protocol) is a protocol designed to manage data from multimedia devices, such as IP cameras , with the ability to send commands: "start", "record", "stop", etc.
RTCP (Real-Time Transport Control Protocol) is a real-time control packet transmission protocol that works in conjunction with RTP, providing feedback and data transmission quality control.
IGMP (Internet Group Management Protocol) is a protocol that allows you to organize network devices into groups using a router. For example, to transfer data from a video server to multiple clients receiving video broadcast.
ICMP (Internet Control Message Protocol) - a protocol that sends data error messages, for example: "authentication error", "port unreachable", "destination node unknown", etc.
ARP (Address Resolution Protocol) is a protocol that determines the MAC address by a known IP address.
MAC Address (Media Access Control) is a unique identifier stored in the memory of each network device.
SOCKS is a protocol that allows software clients behind a firewall to access external servers. And vice versa - external clients connect to servers behind a firewall.
PPP (Point-to-Point Protocol) is a protocol for direct communication between two network nodes, with the possibility of data compression and encryption.
PPPoE (Point-to-point protocol over Ethernet) is a protocol for transmitting PPP protocol frames over Ethernet networks.
Bonjour is an automatic discovery service for network devices in near network environments that use data from DNS .
UPnP (Universal Plug and Play) is a technology that automatically connects and configures network devices immediately after connecting to a network. This technology greatly facilitates the use of network devices to ordinary users.