Frame relay technology is a high-performance WAN protocol running at the physical layer and data link layer. It is a packet switching technology that enables user terminal devices to dynamically share network media and available bandwidth. Variable-length data frames are used to transmit user data more efficiently and flexibly. These frames are transmitted between different network segments until they reach their destination. Frame Relay uses statistical multiplexing technology to make more flexible and effective use of bandwidth.
Frame relay technology has evolved from X.25 packet switching technology. Frame relay only runs on the second layer. The intermediate nodes of the network do not perform excessive error checking. Frame relay operates on a more reliable WAN line. The higher performance and higher transmission efficiency make frame relay more suitable for current WAN applications, such as LAN interconnection. Frame Relay provides users with PVC / SVC, and can provide CBR / VBR and other functions based on VC. Frame relay uses FECN / BECN and other methods to avoid congestion.
Frame Relay Network provides users with N * 64K-45M private line access.
The development of the frame relay network has been greatly developed since the 1990s, and it has also developed vigorously in China in recent years. Whether it is a telecommunications operator as a public service network or a private network for finance and other industries, it has been widely used. ATM is a cell relay technology, suitable for various data transmission, such as: voice, video and data, ATM terminal equipment encapsulates various data types in fixed-length cells, and the cells are transmitted between ATM switches , Can make more convenient and flexible use of bandwidth resources.
ATM is a cell switching and multi-channel taking technology, which combines the advantages of circuit switching and packet switching, and provides scalable bandwidth (Mbps--Gbps). The asynchronous nature of ATM makes ATM more effective than synchronous taking technology.
ATM is a connection-oriented technology, which means that VC must be established on the ATM transmission network before the terminal equipment communicates.
The ATM service network provides users with 2M-155M access methods, mainly serving broadband business users. The ATM public transmission network has also been greatly developed in recent years, and is mainly suitable for broadband and multimedia service users. The ATM transmission network is flexible and applicable to the formation of integrated service platforms such as data and private line services, and its QoS function also has advantages.
CISCO WAN switch MGX / BPX / IGX series products use unified cell exchange between relay nodes, and the relay bandwidth ranges from 2M-622Mbps. Such wide area network switches such as CISCO provide users with ATM service modules, frame relay modules and circuit simulation modules, etc., thus providing a unified hardware platform for the construction of ATM / frame relay transmission networks.
Heli Golden Bridge Frame Relay / ATM Solution
1. Network architecture
A frame relay network (CISCO company products BPX8620 / IGX8400, IGX8430 / IGX8420) 6 core nodes are composed of optical fiber (622Mb / s rate) to form a mesh core layer. / s or 2Mb / s to two nearby main core layer or access layer nodes, the local relay network is connected to the national backbone network with an NNI interface rate of 34Mb / s, and the regional packet network is frame forwarded with 2Mb / s trunk is connected, the whole network is managed by the main and backup network management of two core nodes.
Core layer
Six core nodes are connected to the tandem layer, the relay rate between core layer switches is 622Mb / s, and the rest are 155M / 34M / 2Mbps.
Access layer
More than 30 access nodes are added. The Cisco solution is all equipped with IGX8420 switches. The nodes with large traffic use 155Mb / s and 2Mb / s each (Cisco recommends 155Mb / s and 8x2Mb / sIMTM trunk), The electrical port is used to transmit to two core layer nodes via SDH equipment, and the nodes with small traffic have at least two 2Mb / s connected to the core layer or access layer in two directions.
The Cisco network solution uses Cisco's BPX8600 switches and the original BPX8600 series to form the core layer, and the IGX8400 series switches and the original IGX16 series devices together form the access layer. The network mainly provides frame relay services.
The biggest features of the Cisco solution are: mature multi-service network platform, rich networking experience, superior flow control mechanism, carrier-class reliability and availability, and open standard system platform.
2. Technical characteristics of the plan
Network technology standard
As a carrier-grade network, standardization is crucial. As an active participant in various standards organizations, Cisco has been at the forefront in the formulation and implementation of standards. Cisco has always adhered to the standardization of protocols, technological advancement, and product interconnectivity. From the beginning, it has been committed to the interconnection between different networks and different protocols. Cisco is one of the founders of the Frame Relay Forum and ATM Forum. Not only is it the main leader in the formulation and implementation of standards and specifications, but all products fully comply with the standards of the ITU, ATM Forum and Frame Relay Forum. An example of Cisco ’s leadership and active participation in the development of the ATM Forum (ATMF) technical specifications is: In 1997, the ATM Forum ’s TrafficManagementSpecIfIcaTIon version 4.0 was certified. In the development process of Traffic ManagementSpecificaTIon4.0, Cisco representatives made a great contribution to the preliminary work. These developments are based on ForeSight and Cisco's proven loop ABR congestion management system. The contributions made by Cisco laid the foundation for the development and certification of the forum ’s ABR specification. Cisco's solution supports the standards required by Beijing Telecom. In addition, CISCO plays an important role in various international standardization organizations:
CISCO is one of the four founding companies of the ATM Forum (Cisco, NET, Nortel, Sprint), and is the chairman of multiple working groups, presiding over the drafting of multiple standard specifications;
CISCO is also one of the four founding companies of the FR (Frame Relay) Forum (Cisco, StrataCom, DEC, Nortel), and is the chairman of multiple working groups, presided over the drafting of multiple draft standards and specifications; Produced frame relay switches and has an absolute advantage in market share and is called "" Frame Relay Technology Pioneer "manufacturer)
MSF (Multi-Service Exchange Forum): Founded by Cisco / MCIWorldCom / Bellcore this year, it aims to formulate corresponding international specifications for a new generation of multi-service telecommunications networks emerging internationally.
In addition, in the IETF (International Internet Standardization Organization), Cisco is the main member, and as the chairman of multiple working groups, submitted multiple draft documents. It is worth mentioning that the chairman of the MPLS working group is a scientist from Cisco, and almost all the documents of this working group were drafted by Cisco.
In ITU-T (International Telecommunication Union), Cisco, as the main member, actively participated in the formulation of various standards of the organization.
Network technology maturity
BPX8600 / IGX8400 is the result of many years of research and development of cell switching technology by Cisco. It has mature and rich system software and hardware platforms. BPX / IGX has been widely used all over the world since it was put on the market. With the continuous emergence of new technologies and standards, Cisco has continuously updated and perfected BPX / IGX series switches, making it the most complete and superior WAN switch on the market. User tests have shown that as the most mature ATM switch, BPX8600 / IGX8400 solves the problems that many other switches are trying to solve, such as congestion control, network bandwidth management, and service quality.
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