Router standard technology you do not know (1)

Due to the continuous advancement of social informatization, people's demand for data communication is increasing. Since the launch of TCP/IP protocol clusters in the middle of 1970s, it has become a factual standard for network layer communication protocols. TCP/IP-based interconnected networks have become the largest and most important networks. As the core device of an IP network, routers have been widely used.

As the core equipment of the IP network, vro has become a key technology in the information industry. Its Equipment plays an increasingly important role in data communication. At the same time, due to the powerful functions and complicated technology of the router equipment, manufacturers have too many choices for the realization of the router. As the core device of the public network, the router must follow the equipment specifications to propose the minimum requirements. Therefore, it is important and necessary to standardize router devices. The standard about the router equipment has been published as follows: YD/T1156-2001 "router Test Specification-high-end router"; YD/T1098-2001 "router Test Specification-low-end router".

Router Definition

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. The router dynamically maintains the route table to reflect the current network topology, and maintains the route table by exchanging route and link information with other routers on the network.

Vro category

Currently, vro classification methods vary. Different classification methods are associated, but not completely consistent. In terms of structure, a router can be divided into a modular structure and a non-modular structure. Generally, a high-end router is a modular structure, and a low-end router is a non-modular structure.

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, which requires fast packet switching capability and high-speed network interfaces. It is generally modular. The Access Router is located at the edge of the network and usually uses a low-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 dedicated router is usually used to optimize router interfaces and hardware for a specific function. For example, the Access Router is used as a dial-up user to enhance the PSTN interface and signaling capabilities; VPN routers enhance tunnel processing capabilities and hardware encryption. broadband access routers emphasize 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, a wire speed router is a high-end router that can forward data packets at the Media rate. The middle and low-end routers are non-wire speed routers, but some new broadband access routers are also capable of wire speed forwarding.

In the formulation of standards, routers can be divided into high-end routers and low-end routers. The backplane exchange capability is greater than 20 Gbit/s, A router with a packet switching capability greater than 20 Mbit/s is a high-end router. A router with a packet switching capability less than 1 Mbit/s is 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. Obviously, there is a gap in the above Division: vrouters with 1 Mbit/s or more and 20 Mbit/s or less have no reference standards. According to the standard series, there should be mid-range router specifications. However, because mid-range routers have no special characteristics, you can refer to low-end routers or high-end routers, so there is no separate standard.

Standard formulation basis

The router standard is mainly based on the RFC documentation. Due to the complexity of the router technology, there are many RFC documents, about hundreds.

In addition, a large number of documents, such as routing protocols, network management protocols, and interface standards, are also very important and will not be listed here. RFC1812, which is the most closely related to routers, is the technical requirement of IPv4 routers. To add or delete a router device, refer to RFC1812 and public telecommunications network equipment standards.

Although the router standard is mainly based on the RFC document, it is not a simple translation. In terms of performance indicators, it is mainly based on the results of the router test. Because a vro involves a large number of technologies, the standard cannot contain the content of all relevant protocols. For details about all protocols, see related protocol standards or RFC documents. However, it is inappropriate to simply translate or list the RFC document numbers and Protocol names. This is because:

Some of the Protocol requirements are important and some are optional. Some requirements are critical in Router applications and are irrelevant to other applications or devices; some manufacturers may choose different features for specific reasons. In addition, in the standard setting, the Protocol that the specified router must implement will not repeat the content of the Protocol, only content that must be implemented in the protocol, optional content, and content that does not need to be implemented can be selected for similar protocols.

The router standard is mainly based on the current Internet technology and the Protocol and RFC documents of the current version. With the updates in these technical fields and the updates of related protocols or RFC document versions, the router standards should be updated or supplemented accordingly.

Standard Scope

Vro supports multiple protocols, such as TCP/IP, IPX, SPX, and AppleTalk. Even the TCP/IP protocol has versions 4 and 6. However, due to the fact that TCP/IP has become a standard, IPv4 occupies an absolute advantage in the network, so the router standard focuses on the specification to support IPv4 devices. IPv6 has its inherent advantages and may be widely used in the future. Therefore, we recommend that the standard router support IPv6, but it is not standardized.

In addition to the routers described in the standard, there are embedded routers and transparent routers. An embedded router is a computer system that provides the operating system function in addition to the routing function. Due to its inherent defects, it is not recommended to use the standard. A transparent router, also known as a shared-address router, is not standardized in the standard, but is not excluded from use.

Router standards are a specification that must be observed by routers working in a complex and diverse Internet. Although the current vro does not fully comply with the standards, gradually complying with the vro standards is an effort. Due to the complexity of the Internet and the diversity of actual situations, the current router standards should be recommended.