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PSTN (Public Switched Telephone Network) is a switched network used for global voice communications. This network has approximately 800 million users and is the largest telecommunications network in the world today. In normal life, such as when we use a landline phone to make a call or use a telephone line to dial the Internet at home, we all use this network. One thing that needs to be emphasized here is that the PSTN network existed for the transmission of voice data from the beginning. PSTN (PublicSwitch Telephone Network) is a telephone network commonly used in our daily lives. As we all know, PSTN is a circuit-switched network based on analog technology. Among many wide area network interconnection technologies, the communication cost required for interconnection through PSTN is the lowest, but its data transmission quality and transmission speed are also the worst, and the PSTN network resource utilization rate is relatively low. It also refers to POTS. It is a collection of all

If you do yoga, meditate, smoke one by one, or eat a lot of refreshing food when you are nervous, please take a break and do so now, because frankly, the content is harder this time! The voice VLAN function allows the access port to transmit voice data streams from IP phones. When a Cisco IP phone is connected to a switch, it will specify the Layer 3 IP priority and Layer 2 Class of Service (CoS) values in the voice data stream sent; for voice, these two values are both 5, and for For other data streams, the default is 0. If the data transmission is uneven, the voice quality of the IP phone will be reduced, so the switch supports the quality of service (QoS) based on IEEE 802.1p CoS. 802.1p provides a mechanism to implement QoS at the data link layer. In the 802.1Q relay header, the information of the 802.1p field is included. Looking at the fields in the 802.1Q tag, you will see a field named "Priority", which contains 802.1p information. QoS uses classification and scheduli

SIP (Session Initiation Protocol) is a multimedia communication protocol formulated by IETF (Internet Engineering Task Force). It is an application layer control protocol for multimedia communication on an IP network. It is used to create, modify and terminate the session process of one or more participants. SIP is an IP voice session control protocol derived from the Internet, which is flexible, easy to implement, and easy to expand. SIP interoperates with the Resource Reservation Protocol (RSVP) responsible for voice quality. It also collaborates with several other protocols, including Lightweight Directory Access Protocol (LDAP) for location, Remote Authentication Dial-in User Service (RADIUS) for authentication, and RTP for real-time transmission. With the advancement of computer science and technology, the IP data network based on packet switching technology has replaced the core position of the traditional telephone network based on circuit switching in the field of communication

IPSec (Internet Protocol Security) is a set of open network security protocols formulated by IETF (Internet Engineering Task Force). It is not a single protocol, but a collection of protocols and services that provide security for IP networks. It provides high-quality, interoperable, and cryptographic-based security guarantees for data transmitted on the Internet. IPSec mainly includes security protocols AH (AuthenticationHeader) and ESP (Encapsulating Security Payload), key management exchange protocol IKE (Internet KeyExchange), and some algorithms for network authentication and encryption. IPSec mainly uses encryption and verification methods. The authentication mechanism enables the data receiver of IP communication to confirm the true identity of the data sender and whether the data has been tampered with during transmission. The encryption mechanism guarantees the confidentiality of the data by encrypting the data to prevent the data from being eavesdropped during transmission. T

SSL is called Secure Sockets Layer. It is a security protocol that guarantees privacy. SSL can prevent the communication between the client and the server from being intercepted and eavesdropped. It can also verify the identities of both parties in the communication and ensure the security of data transmission on the network. The traditional HTTP protocol does not have a corresponding security mechanism, cannot guarantee the security and privacy of data transmission, cannot verify the identity of the communicating parties, and cannot prevent the transmitted data from being tampered with. Netscape uses data encryption, identity verification and message integrity verification mechanisms to provide security guarantees for network transmission. The SSL protocol includes several security mechanisms for identity verification, data transmission confidentiality, and message integrity confidentiality. The authentication mechanism is to use the digital signature method to authenticate the server

What is AP? AP-Wireless Access Point (WirelessAccessPoint) AP is the HUB in the traditional wired network, and it is also the most commonly used equipment when building a small wireless LAN. AP is equivalent to a bridge connecting wired and wireless networks. Its main function is to connect various wireless network clients together, and then connect the wireless network to the Ethernet to achieve the purpose of network wireless coverage.   AP is divided into thin and fat? Thin AP (FITAP): Also known as wireless bridges, wireless gateways, and so-called "thin" APs. Popular understanding of thin AP: It cannot be configured by itself, and a dedicated device (wireless controller) is required for centralized control and management configuration. "Controller + thin AP + router architecture" is generally used for wireless network coverage, because when there are a large number of APs, only the controller is used to manage the configuration, which will simplify a lot of wor