Explore the development direction of broadband Backbone Network Technology

The development of the routing industry has also promoted the upgrade of the broadband backbone network technology. In terms of the network structure, the broadband backbone network will develop towards high efficiency in the future, improve the service quality, traffic monitoring, and network management functions to a higher level. With the rapid development of modern Telecom, computer, and Internet technologies, data, voice, video, and other services are constantly growing and are showing a convergence trend, the existing network is difficult to meet the rapidly growing business needs, and it is strongly necessary to build a new broadband backbone network to carry these rapidly growing businesses.

From the network structure perspective

Physical Layer

SONET Synchronous Optical Fiber Network) has become the most important protocol for long-distance and high-speed optical fiber communication. First, SONET's scalability makes it the first technology to implement a new round of high-speed ports. Because OC-3 (155 Mbps) has become an outdated ancillary technology, OC-48 (2.4 Gbps) port speed is now very common on high-speed routers and switches, OC-768 (40 Gbps) the port speed is coming soon. With the increasing data traffic throughput, SONET has become an important broadband backbone network transmission technology. Prior to the appearance of SONET, each optical fiber equipment manufacturer had its own responsibilities and adopted its own independent technology in product production. The products were not compatible with each other. The emergence of SONET played a role in standardized high-speed optical fiber data transmission.

Data Link Layer

ATM creates a single network for voice, video, and data, and the voice and video stream can be maintained at a low latency and jitter level required by users. At the same time, time-insensitive data can make full use of the remaining channel capacity, which can relatively reduce the cost of providing service quality assurance. Just as SONET has many features that are not included in the definition of traditional physical layer protocols, ATM cannot be completely considered as a data link layer protocol. Although an ATM cell is similar to a typical layer-2 data frame, it has the error correction capability and contains the address information that is very important to the local data link. However, the second-level procedure does not require converting all communication streams into fixed-length cells like an ATM.

ATM has a well-developed quality of service (QoS) without compatibility required by the data link layer. However, as an interface with the physical layer, ATM is undoubtedly very suitable for the definition of Layer 2 protocol. Its first-tier options include many optical fiber transmission methods for transporting ATM cells, including SONET, cat5e twisted pair copper, and T1. Although ATM can also be used as a statistical multiplexing to provide services for a large number of non-real-time data streams, its main advantage is its ability to receive real-time data streams, such as voice and video) without causing jitter and latency.

Network Layer

At the network layer, with the great success of the Internet, IP has become a recognized standard. With the development of technology and the diversity of bearer services, IP is a connectionless protocol that transfers data in an "Best Effort" manner and must provide service quality assurance (QoS) for services ), otherwise, the service quality required by the broadband backbone network cannot be achieved.

On the network layer

In this way, a broadband backbone network composed of the physical layer, data link layer, and network layer forms an architecture of IP, ATM, SONET, and Optical. However, the sonet aps equipment brings an additional "Fault Tolerance tax". To achieve fault tolerance, 50% of the total bandwidth needs to be spent in SONET as a "Fault Tolerance tax ". Therefore, many telecom operators want to remove this layer.

The disadvantages of the IP/ATM/SONET/Optical architecture are gradually exposed as the application goes deeper: low efficiency, complicated equipment, high costs, and complicated management. As the packet forwarding speed of the gib route switch increases to dozens of megabytes and the SONET ports with 155Mbps and 622Mbps, the Internet broadband backbone network is connected to the router through the PPP protocol, this is the structure of IP over SONETPOS. This structure quickly replaces ATM and becomes the mainstream technology of Internet broadband backbone networks. It increases the transmission efficiency from 80% to 95% and simplifies the equipment and reduces costs.

IP over SONET is not the ultimate System of layered simplification. It can further simplify the SONET layer in the broadband backbone network and directly run the IP Application on the Optical channel IP over Optical ). All optical networks do not require complex Link Layer Management on the SONET layer. The inherent distributed survival feature of the Internet gives them protection and self-healing capabilities. SDH and ATM are not used in IP address optimization optical networks. packet forwarding and switching is completed by the Kyrgyzstan routing switch. Because there is no lower-layer transmission protocol available in IP address-optimized optical networks, it is best to perform self-recovery at the network layer. MPLS Multi-Protocol Label Switching can be used) or DPT dynamic packet transmission) to achieve self-healing recovery at the network layer, so that the entire network remains robust and efficient.

From the perspective of Service Quality

The new generation of broadband backbone network is no longer the traditional Internet, and it needs to run more services on its backbone than it is now. The new broadband backbone network structure must provide various services, including voice, data, and video. Therefore, a certain quality of service (QoS) is required. This Quality of Service requires high quality assurance in terms of time delay and transmission error rate. In the network, you must be able to provide business flow control measures and traffic management methods. For the broadband backbone network, the pursuit of maximizing the use of resources, reducing costs, and improving efficiency are fundamental requirements for network construction and network operation. Therefore, at the top of the network, Efficient networking technology is required to make full use of physical resources. Traffic management technology can ensure the service quality of each service in a congested network.

IETF sets up a new working group from the Integrated Service Engineering Group to create Differentiated Services (DiffServ) to implement QoS functions in the broadband backbone network. Another effective mechanism for prioritizing traffic in IP networks is TCP rate control, which is achieved by adjusting the size of the terminal window rather than making it grow at will, TCP speed control can reduce packet traffic on the network. An important issue in IP Broadband backbone network management is how to monitor traffic and prevent and resolve congestion. To adapt to the development of IP over ATM, the Multi-Protocol Label Switching Technology MPLS emerged. MPLS allows you to create virtual circuits for real-time IP service data streams based on tags in an ATM switch to ensure QoS.

In the future, the broadband backbone network will take on the task of unifying the three networks and provide support platforms for various businesses. First, the network must have a high efficiency to make the network layers more concise, so as to achieve high transmission efficiency. In addition, you need to work at the network layer or higher application layers, improve the service quality, traffic monitoring, and network management functions to a higher level.