Router technology Overview (1)

In today's information society, people are increasingly demanding data communication. As the core equipment of the IP network, vro has become a key technology in the information industry.

Vro

A router is a packet forwarding device that works at the network layer of the OSI reference model. The router forwards data packets to achieve network interconnection. Although routers support multiple protocols, such as TCP/IP, IPX, SPX, and AppleTalk, most routers in China run TCP/IP protocols.

A router is usually connected to two or more logical ports identified by IP subnet or Point-to-Point Protocol, and has at least one physical port. The router decides the output port and Next Hop address based on the network layer address in the received data packet and the route table maintained inside the router, and overwrites the data packet header at the link layer to forward the data packet.

A Router usually dynamically maintains a route table to reflect the current network topology. The router maintains the route table by exchanging routing and link information with other routers on the network. Vro is the core device connecting to the IP network.

Vro category

The current vro classification methods vary. Various classification methods are associated, but they are not completely consistent.

In terms of capabilities, routers can be divided into high-end routers and low-end routers. Different manufacturers are divided into different categories. Generally, a router with a backplane switching capability greater than 40 GB is called a high-end router, and a router with a backplane switching capability of less than 40 GB is called a low-end router. Take the Cisco company with the largest market share as an example. The 12000 series are high-end routers, and The 7500 or lower series routers are low-end routers.

In terms of structure, routers can be divided into modular and non-modular structures. High-end routers are generally modular, and low-end routers are non-modular.

Vrouters can be divided into core routers and access routers according to their network locations. The core router is located in the network center and usually uses a high-end router. Fast Packet switching capability and high-speed network interfaces are required, usually in a modular structure. The Access Router is located at the edge of the network, and usually uses a low-end or middle-end router. Relatively low-speed ports and strong access control capabilities are required.

In terms of functions, routers can be divided into general-purpose routers and dedicated routers. Generally, the router is a general-purpose router. A vro is usually used to optimize router interfaces and hardware for specific functions. For example, the Access Server is used as the access dialing user to enhance the PSTN interface and signaling capabilities. The VPN Router enhances the tunnel processing capability and hardware encryption. The Broadband Access Router emphasizes the number and type of broadband interfaces.

In terms of performance, routers can be divided into line rate routers and non-line rate routers. Generally, the wire speed router is a high-end router that can speed up the media

Rate-based packet forwarding. The low-end router is a non-linear-speed router. However, some new broadband access routers also provide fast-forward capabilities.

There are still many router classification methods, and as the development of router technology, there may be more and more classification methods.

Router Functions

Vrouters generally implement the following basic functions:

Implements Internet protocols such as IP, TCP, UDP, and ICMP.

Connect to two or more packet exchange networks. Implement the required functions for each connected network. These functions include:

IP data packets are encapsulated in link layer frames or IP data packets are retrieved from link layer frames.

Sends or receives IP data packets based on the maximum data packet size supported by the network. The maximum transmission unit (MTU ).

Converts the IP address and the link layer address of the corresponding network. For example, convert an IP address to an Ethernet hardware address.

Implement traffic control and Error Indication supported by the network.

Receives and forwards data packets, implements buffer management, congestion control, and fair processing during transmission and receiving.

When an error occurs, identify the error and generate ICMP errors and necessary error messages.

Discards data packets whose TTL domain is 0.

Segment data packets if necessary.

Select the next hop destination for each IP packet according to the route table information.

Supports at least one Internal Gateway Protocol (IGP. Supports external Gateway Protocol Exterior Gateway Protocol and EGP) to exchange topology information with other autonomous domains.

Provides network management and system support mechanisms, including storage/upload configuration, diagnosis, upgrade, status report, exception report, and control.