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When talking about network equipment, we often hear the terms router, switch and optical modem. They are a key component in building modern network infrastructure and undertake the important tasks of connecting, transmitting and managing data. In our daily life and work, we are almost inseparable from their existence. Whether we are surfing the Internet at home, communicating within the office, or browsing web pages on the Internet, we cannot do without these seemingly ordinary but crucial network devices. In this article, Rui Ge will take you to have a good understanding of the three types of network equipment: routers, switches and optical modems.

router

A router is a network device used to transmit data packets between different networks. It has multiple network interfaces that can connect to different networks and transmit data packets from one network to another based on the destination address.

How router works

Routers maintain routing tables to determine how to transmit packets from source addresses to destination addresses. The routing table contains the mapping relationship between network addresses and next-hop addresses.

When a router receives a packet, it looks up the routing table to determine which interface the packet should be sent to, and then forwards it to the appropriate interface.

Routers exchange routing information through routing protocols to update each other's routing tables. Common routing protocols include RIP, OSPF, BGP, etc.

Memory tips: You can only remember three key words about the working principle of the router: routing table management , data packet forwarding , and routing protocol .

Router functions

1. Connect to the network : The router can connect to different networks, such as LAN, WAN, etc., to achieve communication between different networks.

2. **Network Address Translation (NAT)**: The router can implement the NAT function, mapping the IP address in the private network to a public IP address, and realizing communication between the internal host and the external network.

3. Security features : Routers often include firewall features that filter network traffic and protect the internal network from external attacks.

4. Load balancing : Some advanced routers support load balancing function, which can automatically adjust the transmission path of data packets according to network traffic to improve network performance.

Type of router

1. Home router : used for home networks, usually contains wired and wireless interfaces, and supports the connection and sharing of home networks.

2. Enterprise-grade routers : used in enterprise networks, usually with more powerful performance and security features, and can support large-scale network deployments.

3. Core router : used for the core nodes of the Internet, responsible for the transmission and routing of Internet data packets, and has extremely high performance and reliability requirements.

switch

A switch is a network device used to transmit data packets within a local area network. It has multiple ports that can connect multiple computers or other network devices and exchange data between them.

How the switch works

The switch builds a MAC address table by learning the MAC address of the connected device on each port and associating it with the port.

When the switch receives a data frame, it looks up the MAC address table to determine which port the data frame should be sent to, and then forwards the data frame to the corresponding port.

If the switch cannot find the destination address in the MAC address table, it broadcasts the frame to all ports (broadcast) or sends the frame to all ports except the receiving port (flooding).

Memory tips: You can only remember three key words about the working principle of the router: MAC address learning , data frame forwarding , broadcast and flooding .

Switch functions

1. LAN connection : The switch can connect multiple computers or network devices within the LAN to achieve internal communication and resource sharing.

2. Data frame filtering : The switch can filter data frames according to the MAC address table and only send data frames to the target device to improve network efficiency.

3. Data frame forwarding : The switch can achieve fast data frame forwarding and support high-speed LAN data transmission.

4. Virtual LAN (VLAN): Some advanced switches support the VLAN function, which can divide the LAN into multiple logical network segments to enhance network security and management flexibility.

Type of switch

1. Unmanaged switch : Also known as an unmanaged switch, it is typically used in home or small office networks and has a simple configuration and management interface.

2. Managed switch : Also called a smart switch, it has more management functions, such as VLAN, QoS, port mirroring, etc., and is suitable for small and medium-sized enterprise networks.

3. Managed switches : Also known as enterprise-class switches, they offer higher performance and reliability, supporting large-scale network deployments and complex management needs.

light cat

Optical Network Terminal (ONT) is a terminal equipment used in optical fiber networks. It is usually installed in the user's home or office and is used to convert optical fiber signals into electrical signals for use by terminal equipment.

How the light cat works

Optical modems receive optical signals through optical fibers, which contain data streams from network service providers.

The optical modem converts the received optical signal into an electrical signal for connection to a terminal device such as a computer, phone or router.

The converted electrical signal is transmitted to the terminal device through the Ethernet port or Wi-Fi signal to achieve network connection.

Memory tips: You can only remember three key words for the working principle of the router: optical signal reception , photoelectric conversion , and data transmission .

The function of light cat

1. Optical signal conversion : Optical modem converts optical fiber signals into electrical signals so that user terminal equipment can access the optical fiber network.

2. Network connection : Optical modem can connect to user equipment through Ethernet port or Wi-Fi signal to achieve network access.

3. Telephone access : Some optical cats also have telephone interfaces that can convert voice signals into digital signals to implement IP telephone services.

Types of light cats

1. Independent optical modem : An independent optical modem is a separate device, usually provided to users by network service providers, for connecting to the optical fiber network of the user's home or office.

2. Integrated optical modem : Integrated optical modem is a device that integrates the functions of a router and an optical modem, and can provide more network functions, such as Wi-Fi routing, firewall, etc.

Switch, router, optical modem: what is the connection sequence?

The sequence of connecting switches, routers and optical modems is a key step in network cabling, which directly affects the performance and functionality of the network.

light cat

Optical modem is a terminal device connected to an optical fiber network, which converts optical signals into electrical signals. Optical modems are usually provided by network service providers, and their connection sequence is the first step in the network.

The main function of the optical modem is to receive optical signals and convert them into electrical signals that network devices can understand. It is responsible for connecting users' homes or offices to fiber optic networks. Optical modems are usually installed at the network entrance in the user's home or office, that is, the fiber access point provided by the network provider.

router

The router is the second network device connected to the optical modem. It is responsible for managing the data traffic in the network and controlling the transmission of data packets from one network to another. Routers are also key devices for connecting to the Internet.

Routers have a variety of functions, including network address translation (NAT), packet filtering, security protection, and more. It separates the internal network from the external network and protects the internal network from external attacks. The router is usually installed behind the optical modem and serves as the key bridge connecting user equipment and the Internet. It can be connected to the optical modem’s Ethernet port or fiber optic port.

switch

A switch is a device connected behind a router that is used to exchange data packets within a local area network, allowing multiple devices connected to it to communicate with each other and share resources.

Switches are mainly used for data exchange and flow control within the LAN. It can provide high-speed data transmission and fast communication between multiple devices. The switch is usually installed behind the router and connected to the router's Ethernet port. It can connect multiple computers, printers, servers and other LAN devices.

Memory tips:

Optical modem : A terminal device connected to an optical fiber network and responsible for converting optical signals into electrical signals.

Router : The second network device connected to the optical modem, responsible for managing network traffic and connecting the internal network to the external network.

Switch : A device connected to the back of a router for data exchange and communication within a LAN.

Router vs switch vs optical modem

1. Function:

• Router : Mainly responsible for data packet forwarding and routing management between different networks, and realizing network interconnection and security functions, such as NAT, firewall, etc.

• Switch : used for data exchange within the LAN, forwarding data frames from one port to another, providing fast communication between devices within the LAN, and supporting functions such as data frame filtering and VLAN.

• Optical modem : Optical modem is mainly used in optical fiber networks to convert optical signals into electrical signals, connect user terminal equipment to the optical fiber network, and provide Internet access and telephone services.

2. Application scenarios:

• Router : Commonly found in homes, businesses, and Internet core nodes, used to connect different networks and provide network security functions.

• Switch : Mainly used inside local area networks, such as offices, data centers, etc., to connect multiple computers and network equipment to achieve internal communication and data exchange.

• Optical modem : Usually installed in the user's home or office, it is used to connect user terminal equipment to the optical fiber network and provide Internet access and telephone services.

3. Connection method:

• Router : Can connect to different types of networks, such as LAN, WAN, etc., with multiple network interfaces.

• Switch : Connects multiple computers or network devices within a LAN and has multiple Ethernet ports.

• Optical modem : Connects optical fiber networks and user terminal equipment, usually with Ethernet ports or Wi-Fi capabilities.

4. Management and configuration:

• Router : Usually requires more complex configuration and management, including routing settings, security settings, etc., which can be managed through the web interface or command line.

• Switch : Management and configuration are relatively simple, mainly including VLAN settings, port mirroring, etc., and can be managed through the web interface or command line.

• Optical modem : Generally pre-configured by the network service provider, users usually do not need to perform any configuration and can use it simply by connecting to the terminal device.

Analyze and discuss.