Detailed analysis of VPN and IPv6 technologies in vro Technology

With the development of China's routing industry, it also promotes the wide application of the router technology. Here we analyze the VPN and IPv6 technologies in the router technology, fiber optic and DWDM are mature and ready-made among the three main technologies used by core internet in the future. If there is no router corresponding to the original bandwidth provided by the existing optical fiber technology and DWDM technology, the new network infrastructure will not be able to fundamentally improve the performance, therefore, developing high-performance backbone switches/routers (vrouters) has become an urgent requirement. The Tbit router technology is still in the development experiment stage.

Router Technology

Router Architecture

From the perspective of architecture, the router technology can be divided into the first generation single-CPU Single-structure router, the second generation single-bus master-slave CPU Structure router technology, and the third generation single-bus symmetric multi-CPU Structure router; the fourth generation multi-bus multi-CPU Structure router, the fifth generation shared-memory structure router, the sixth generation cross-Switch Architecture router technology, and the vro Based on the cluster system.

Router Composition

A vro has four elements: the input port, the output port, the switch, and the route processor. The input port is the entrance of the physical link and input package. A port is usually provided by a line card. A line card generally supports 4, 8, or 16 ports. An input port has many functions. The first function is to encapsulate and deencapsulate the data link layer. The second function is to find the destination address of the input package in the forwarding table to determine the destination port (called route lookup). routing lookup can be implemented using common hardware, alternatively, you can embed a microprocessor into each line card. Third, to provide QoS (Service Quality), the port should divide the received packet into several predefined service levels. Fourth, ports may need to run data link-level protocols such as SLIP (Serial Line Internet Protocol) and PPP (Point-to-Point Protocol) or network-level protocols such as PPTP (Point-to-Point Tunneling Protocol. Once the route query is complete, you must use the switch to send the packet to its output port. If a router is added to a queue at the input end, several inputs share the same switch. In this way, the last function of the input port is to participate in the arbitration agreement for public resources (such as the switch.

The switch can be implemented using different technologies. So far, the most widely used switch technology is bus, cross switch and shared storage. The simplest switch uses a bus to connect all input and output ports. The disadvantage of the bus switch is that its switching capacity is limited by the capacity of the bus and the additional overhead for shared bus arbitration. The crossover switch provides multiple data paths through the switch. A crossover switch with N × N intersections can be considered to have 2N buses. If a crossover is closed, the data on the input bus is available on the output bus; otherwise, the data is unavailable. The scheduler controls the closing and opening of intersections. Therefore, the scheduler limits the switching speed. In the shared storage router technology, the incoming packets are stored in the shared storage, and only the packet pointer is exchanged, which improves the switching capacity. However, the switch speed is limited by the storage device access speed. Although the storage capacity can double every 18 months, the storage access time is reduced by only 5% each year, which is an inherent limitation of the shared storage switch.

The output port stores packets before the packets are sent to the output link. complex scheduling algorithms can be implemented to support priorities and other requirements. Like the input port, the output port must also support encapsulation and encapsulation of the data link layer, as well as many advanced protocols. The Route Processor calculates the forwarding table to implement the routing protocol and runs the software for configuring and managing the router. At the same time, It also processes packages whose destination addresses are not in the wire adapter forwarding table.