Router basics-vro Functions

This article describes in detail the basic knowledge and functions of a router. What is the basic working principle of the router? The following article will give you a detailed answer.

The principle and function of a router is a typical network layer device. It is an indirect frame transmission data of two LAN networks. It is called an intermediary system in OSI/RM to complete network layer relay or layer-3 relay tasks. The router is responsible for transmitting data through indirect frames at the network layer of the two local networks. When forwarding frames, the addresses in the frames must be changed.

Router basics 1. principles and functions

Vrouter) is used to connect multiple logically separated networks. The so-called logical network represents a separate network or a subnet. When data is transmitted from one subnet to another, it can be done through a router. Therefore, a router can determine the network address and select the path. It can establish flexible connections in Multi-network interconnection environments, A vro can connect to different subnets using different data groups and media access methods. The vro only accepts information from the source station or other routers and belongs to an interconnected device at the network layer. It does not care about the hardware devices used by each subnet, but requires that software that is consistent with the network layer protocol be run. Vrouters are divided into local routers and remote routers. Local routers are used to connect network transmission media, such as optical fiber cables, coaxial cables, and twisted pair wires. Remote routers are used to connect remote transmission media, and require the corresponding equipment, such as telephone lines to be equipped with a modem, wireless to be through the wireless receiver, transmitter.

Generally, a vro should be used to connect a heterogeneous network to multiple subnets.

The main task of a router is to find an optimal transmission path for each data frame passing through the router and transmit the data to the destination site effectively. It can be seen that the routing algorithm is the key to selecting the optimal path. To do this, the route Table Routing Table is stored in the router for Routing selection. The path table contains the subnet flag information, the number of online routers, and the name of the next router. The path table can be set by the system administrator or dynamically modified by the system. It can be automatically adjusted by the router or controlled by the host.

1. Static path tableThe system administrator sets a fixed path table in advance to call it a static path table. Generally, it is set in advance according to the network configuration during system installation, it will not change as the network structure changes in the future.

2. Dynamic Path tableDynamic) the path table is automatically adjusted by the router according to the running status of the network system. The router selects the Routing Protocol) to automatically learn and remember the network running status, and automatically calculate the optimal path for data transmission as needed.

Router basics 2. Advantages and Disadvantages of routers

1. Advantages

Suitable for large-scale networks;

Complex network topology, load sharing, and optimal path;

Better Processing of multimedia;

High Security;

Isolate unnecessary traffic;

Saves the bandwidth of the LAN;

Reduce the burden on hosts.

2. Disadvantages

It does not support non-routing protocols;

Complicated installation;

High price.

Router basics 3. Router Functions

1) intercept packets sent to the remote network segment between networks, thus forwarding.

2) select the most reasonable route to guide communication. To achieve this function, the router needs to search for the route table based on a certain route communication protocol. the routing table lists the nodes contained in the entire interconnected network, and the path between nodes and the transfer fee associated with them. If there is more than one path to a specific node, select the optimal and economical path based on the pre-determined criteria. Because various network segments and their interconnection conditions may change, the routing information needs to be updated in a timely manner, this is done by the scheduled update specified by the routing information protocol in use or by changing the situation. Each router in the network dynamically updates the route table it maintains according to this rule to maintain valid route information.

3) in the packet forwarding process, the router splits large data packets into appropriate data packets to facilitate packet transmission between networks according to predefined rules, after arriving at the destination, package the decomposed data packets into the original form.

4) A multi-protocol router can connect to a network segment using different communication protocols as a platform for communication and connection between different communication protocol network segments.

5) The main task of a vro is to direct the communication to the destination network and then reach the specific node site address. The latter function is implemented through network address decomposition. For example, assign the network address to a group of nodes in the network, subnet, and region, and specify the special stations in the subnet. Hierarchical Addressing allows routers to address network storage addresses with many node sites.

Vrouters within the WAN can be divided into two types based on their forwarding packet performance: intermediate node router and border router. Although the names used by these two types of routers may vary greatly in the constantly improved routing protocols, they play the same role.

The intermediate node router provides packet storage and forwarding during transmission over the network. At the same time, based on the routing information maintained by the current route table, select the best path to send packets. A vro connected to an external Wan on the company or enterprise network side composed of multiple interconnected LANs is the border router of the enterprise network. It collects addressing information from the external Wan to the enterprise's network and forwards it to the network segments related to the enterprise's network. On the other hand, it concentrates the packets sent from each LAN segment in the enterprise's network to the external Wan, determine the best transmission path for related packets.

We use an example to describe how a vro works.

For example, workstation A needs to transmit information to workstation B and assume that workstation B's IP address is 120.0.5). They need to be transmitted through multiple routers, and the distribution of routers.

Its working principle is as follows:

1) workstation A sends the address 120.0.5 of workstation B together with the data information to vro1 1 as A data frame.

2) After receiving the data frame of workstation A, vro1 1 extracts the address 120.0.5 from the header and calculates the optimal path to workstation B Based on the path table: r1-> R2-> R5-> B, and send the data frame to vro2 2.

3) vro2 2 repeats vro1 1 and forwards data frames to vro5 5.

4) vro5 5 extracts the destination address and finds that 120.0.5 is in the network segment connected to the vro5. Therefore, the data frame is directly handed over to workstation B.

5) workstation B receives the data frame of workstation A, and the communication process ends.

In fact, in addition to the above-mentioned routing selection, the router also has the network traffic control function. Some routers only support a single protocol, but most routers support transmission of multiple protocols, that is, multi-protocol routers. Because each protocol has its own rules, to complete multiple Protocol algorithms in a router, it is bound to reduce the performance of the router. Therefore, we believe that the performance of vrouters supporting multiple protocols is relatively low. When purchasing a vro, You need to select the desired network protocol vro based on your actual situation.

In recent years, the exchange router product has emerged. In essence, it is not a new technology, but to improve the communication capability and combine the principle of the switch into the router, so that the data transmission capability is faster and better.