Gateway What is a gateway The function and classification of the IoT gateway

 What is a gateway? It is easy to understand and it is mainly used as a bridge between various sensors, devices and the cloud or uplink system to transmit the data of the perception layer to the cloud or server. The perception layer collects various data and working conditions, analyzes and converts various equipment protocols, completes the collection, transmission, aggregation and filtering of equipment data, realizes equipment access to the cloud, and completes industrial reform.

The function of IoT gateway:

1. Protocol conversion

 Protocol conversion from different perception networks to access networks, uniform encapsulation of data in the standard format of the lower layer, ensuring that the protocols of different perception networks can become unified data and signaling; parsing the data packets sent by the upper layer into perception Signaling and control instructions that can be recognized by layer protocols.

2. Controllability and management ability

First of all, the gateway must be managed, such as registration management, rights management, status supervision, etc. The gateway realizes the management of the nodes in the subnet, such as obtaining the identification, status, attributes, energy, etc. of the nodes, and realizing wake-up, control, diagnosis, upgrade and maintenance remotely, etc. Due to the different technical standards of the subnets and the complexity of the protocols, the gateways have different management capabilities.

3. Data filtering function

Sometimes, sensors/devices will generate a large amount of data, which will put a lot of pressure on the system, and the transmission and storage costs will increase accordingly. Usually in this case only a small part of the data is valuable and the rest is filtered out. For example, the camera does not need to send video data of the hallway. Gateways can preprocess and filter data generated by sensors/devices to reduce transmission, processing and storage requirements.

4. Extensive access capabilities

At present, there are many technical standards for short-range communication. At present, the standardization work for IoT gateways is being carried out at home and abroad, such as 3GPP and the sensor working group, to realize the interconnection and interoperability of various communication technology standards.

Gateways are roughly divided into three categories by function:

1) Protocol gateway: As the name implies, the main function of this type of gateway is protocol conversion between networks of different protocols. Since the development of the network, there have been several general types such as: 802.3 (Ethernet), IrDa (Infrared Data Association, Infrared Data Association), WAN (Wide Area Networks, wide area network) and 802.5 (Token Ring), X2.5, 802.11 a, 802.11b, 802.11g, WPA, etc. Different networks have different data encapsulation formats, different data packet sizes, and different transmission rates. However, data sharing and communication between these networks is inevitable. In order to eliminate the differences between different networks and enable the smooth exchange of data, we need a dedicated translator, that is, a protocol gateway. It is by him that a network can understand other networks, and it is also by him that different networks are connected to form a huge Internet.

2) Application gateway: It is mainly set up for some special applications, and its main function is to convert one data format of a certain service into another data format of the service, so as to realize data exchange. This kind of gateway is often used as a server for a specific service, but it also has the function of a gateway. The most common such server is a mail server. We know that there are several formats of e-mail, such as POP3, SMTP, FAX, X.400, MHS, etc., if the SMTP mail server provides gateway interfaces for POP3, SMTP, FAX, X.400, etc., then we can Send emails to other servers through the SMTP mail server without any scruples.

3) Security gateway: The most commonly used security gateway is the packet filter, which actually authorizes the original address, destination address, port number, and network protocol of the data packet. By filtering the information, the data packets with permission are transmitted through the gateway, and the data packets without permission are intercepted or even discarded. This is similar to the software firewall in a certain sense, but compared with the software firewall, the security gateway has a large amount of data processing and a fast processing speed, which can well protect the entire local network without causing a bottleneck to the entire network.