The role of the router:

1. Heterogeneous network interconnection: such as network interconnection with different seed network protocols

2. Subnet protocol conversion: protocol conversion between different subnets including LAN and WAN

3. Routing: That is to find the way

4. Rate adaptation: use its own buffer and flow control protocol to adapt

5. Isolate the network: prevent broadcast storms, and also implement firewalls

6. Packet fragmentation and reassembly: packets exceeding the MTU of the interface will be fragmented, and packets arriving at the destination will be reorganized

7. Backup and flow control: switching between main and standby lines and complex flow control

The working principle of the router:

The router works at the third layer of the OSI seven-layer protocol, which is the network layer. Its main task is to receive a data packet originating from a network interface, and according to the destination address contained in the data packet, determine the next destination address to be forwarded to. The router maintains a routing table at all times, and all data packets are sent and forwarded by looking up the routing table. This routing table can be configured statically or generated through a dynamic routing protocol.

The physical layer of the router receives a message from a port of the router and sends it to the data link layer. The data link layer removes the link layer encapsulation and sends it to the network layer according to the protocol field of the message. The network layer first sees whether the message is sent to the local machine, if so, remove the network layer encapsulation and send it to the upper layer. If not, the routing table is searched according to the destination address of the message. If a route is found, the message is sent to the data link layer of the corresponding port. After the data link layer is encapsulated, the message is sent. If no route is found, the packet is discarded.

To know more please visit https://www.e-lins.com/EN/.