Wireless network optimization of the four typical cases

1. Gigabit Ethernet technology advantages

In LAN in order to maintain a diameter of 200 m the greatest regional impact, the smallest CSMA / CD-carrier, Ethernet-time from the current 512-bit extended to 512 bytes (4096 bits), the smallest packet size at 64 characters Festival. Expansion of the carrier does not modify the minimum size of the package solution under the conditions of the CSMA / CD inherent in the timing issue. Although these changes may affect the performance of small packets, but this impact has been CSM / CD algorithm called packet sudden offset by the transfer of properties. Gigabit Ethernet the biggest advantages is that its existing Ethernet compatibility.

With 100 M Ethernet, Gigabit Ethernet and 10 M using the same Ethernet frame format and frame size, and the same CSMA / CD agreement. This means that the majority of the Ethernet users of the existing Ethernet smooth, without interruption of the upgrade, but without adding additional protocol stack or middleware. At the same time, Gigabit Ethernet also inherited the Ethernet other advantages, such as high reliability and easy management.

Compared to other Gigabit Ethernet technology has the advantages of large bandwidth, and still has room for development, the standards body is developing 10 G Ethernet technical specifications and standards. At the same time frame based on Ethernet and IP-layer priority control mechanism and protocol standards and various support QoS technologies matured, to implement the requirements of a better quality of service provided the basis for the application. With fiber optic transmission manufacturing and technological progress, Gigabit Ethernet transmission distance up to 100 kilometers, which makes its construction of MAN and has gradually become a wide-area network technology options.

The main advantage of using Gigabit Ethernet is: Gigabit Ethernet will provide 10 times the performance of Fast Ethernet and 10/100 Ethernet with the existing standards-compliant. At the same time 10/100/1000 Mbps for the development of the virtual network standards 802.1 Q and 802.1 p priority standards have been promoting, Gigabit network backbone network has become a mainstream technology.

June 1998 have been developed to complete the first Gigabit Ethernet standard 802.3 to use optical fiber cable and copper cable short-range target of full-duplex link. For half-duplex and long-range copper cable standards 802.3 ab introduced in 1999.

Gigabit Ethernet will provide the perfect way to transfer the full protection of the existing network infrastructure investment. Gigabit Ethernet will retain 802.3 and 802.3 Ethernet frame format and the management of the target specifications, which will enable enterprises to upgrade to Gigabit performance, while retaining the existing cable, the operating system, the agreement, desktop Applications and network management strategies and tools.

Gigabit Ethernet compared to the original Fast Ethernet, FDDI, ATM and other network solutions, providing an alternative to improve exchanges between the backbone and switches and connections between switches and servers connected to a reliable and economic way . Web designers will be able to establish an effective use of high-speed, mission-critical applications and file backup of high-speed infrastructure. Network management will provide users with the Internet, Intranet, metro and wide area network of more rapid access.

Gigabit products provider, has a complete line of Gigabit Ethernet products, can fit user needs to provide a complete solution. From the core network backbone switches to the edge of the client server Gigabit access, a user needs for the design of high-performance products. Gigabit Ethernet switch deployment, is a very impressive technology. At present, many manufacturers switch to Level 2 and Level 3 exchanged exchange into one, regardless of the exchange or routing, will provide at least 10 million pps the forward rate, and even some products can reach 20 million pps. These high-performance characteristics of the Intranet has been speaking it is very important, because the traditional law of nature LAN traffic 80/20 (80% of the working group in the local traffic network and 20 percent of the traffic flows backbone network) is already outdated.

Gigabit Ethernet high-speed multi-packet forwarding capability is Gigabit Ethernet technology can provide the best example of the strong price performance. In addition, Gigabit Ethernet networking technology to reduce the long-term cost of ownership is also of great benefit.

2. Gigabit network switching technology

From the beginning of the end of 1996, some companies have introduced integrated Layer 2 switching and routing of Layer 3 switching products, the technology called "multi-layer exchange (multilayer switching)". It Layer 2 switching technology to increase the routing of services and support the choice of broadcast and multicast suppression, and VLAN support VLAN between the transmitted data packets and firewall features full support for TCP / IP and IPX routing.

After nearly four years of development, these features have been constantly improved and strengthened, making multi-layer switch router than the traditional price-performance than the 8-16 times. The switch to a new generation of multi-Gigabit Ethernet switching technology as the core, can provide a more attractive price-performance, is the sector-level network and data center network to replace traditional routers can provide the ideal of multi-exchange Switches. At the same time, its direct transmission distance has now reached 130 km, can achieve a Gigabit Ethernet as the backbone of the enterprise LAN backbone transmission rate to 2 Gbps (full-duplex mode).

Promoting technological development of the main factors to promote the exchange of high-speed multi-technology development is the biggest factor used cheap 10/100 M adaptive card of the large number of Internet and Intranet deployment. At present the network has been away from the traditional c / s calculations from the more hierarchical structure, the traditional c / s model of the 80/20 rule has become the flow of the past. In the network design, the traditional router and Hub Layer 2 switches or the network deployment model will also become history.

In addition, Intranet support more complex and bandwidth-sensitive multimedia data streams, such as data, documents, images, animation, sound and video. An Intranet end-users at least the bandwidth requirements of non-Intranet users and more than 50% to 100%. At the same time, broadband access has become a trend.

Another noteworthy problem is, to provide users with Fast Ethernet connections can provide more bandwidth cushion to deal with unexpected traffic, it is 10 BASE-T technologies second to none. IP sudden flow is one of the characteristics of network applications. Low-cost and high-bandwidth makes Fast Ethernet regardless of the client or the server side have been widely used.

In order to non-blocking traffic flow and the ability to handle unexpected strike a balance between the need to provide next-generation switch platform above the request of users connected to 8 to 16 times the rate of the trunk link, and to Gigabit Ethernet is to meet the trunk Client's Fast Ethernet connectivity service requests. This is sufficient to handle unexpected flow is very important.

At the same time, the campus network or MAN, whether across several network layer, the random Intranet traffic required to provide end-to-end, high-performance continued unchanged. To achieve this, in a switch from a high-performance level 2 and 3 of the transponder capacity is the only solution.

Non-blocking ability and have a choice of forwarding is the main user demand. And all kinds of very effective network management tool enables network administrators to effectively and efficiently into their business strategy forward in the engine, its performance through real-time monitoring network management software. This will fundamentally help users under the company's short-and long-term business development need to identify and deliver the necessary services. A new generation of Gigabit Ethernet switches to support these features and services, but also support a common routing protocol, such as IP / RIP or IP / OSPF, and so on. This greatly reduced the complexity of network equipment.

3. Network design objectives and principles

The high-performance network systems meet the requirements of the core network switches Centre massive data exchange requirements, even the center of communication link bandwidth of the network to meet the performance requirements. Whether the enterprise network or MAN, WAN, the information on its applications are at an unprecedented pace, with new multimedia applications and new data applications on a higher bandwidth requirements. To corporate Intranet network commonly used model, its WWW server, FTP server, Lotus Notes groupware application server, Novell Server and other server group supports the entire enterprise information service environment. Enterprise customers all departments client application software, network access through the centre servers, application requests, query the database. The network traffic load from the brink of major equipment to the core data exchange, with corporate business development, size of network expansion, and the application of the exchange of information increased, making the corporate network usually occur first in the core communication bottlenecks. Improve enterprise campus LAN network performance data exchange, is often the first to expand the exchange of core switches, equipment to increase the edge of the core data communication bandwidth, in order to reduce the bottleneck of the network, making application performance and efficiency is improved. So in designing enterprise campus LAN principle, it should first meet to consider the scale of network equipment required by the core data exchange capacity and equipment to the edge of the core link bandwidth.

3.1 reliability and availability

Network system design of equipment and high-reliability high-availability systems; asked all the key components of the core switches can achieve redundancy, online replacement (plug), the fault recovery time interval in the second grade to be completed. Multi-level fault-tolerant design is based on a single high-reliability equipment on the basis of further improve system availability.

On enterprise applications, through its advanced computer, networking and other information technology, production process automation, paperless office automation and improve the company's production, management efficiency and level. Support for enterprise application infrastructure is the business park network, it will directly affect the working conditions of office applications to the corporate environment, trade, production, development, design and other business environment, financial management, parts management, environment, information retrieval and database query , Internet browsing and other business support services necessary to the normal operation of the facilities function. Network reliability requirement is to protect the enterprise application environment of the primary condition for normal operation, reliability of the network requirements for high-availability network. The choice of network equipment, especially the core chassis of equipment, should be able to configure redundant components, key components of a single point of failure does not exist, that is, like power switches, fans, the exchange of engine management module of these components can be redundant backup One of the components of any damage will not affect the normal operation of equipment, will not affect network connectivity. To provide network equipment reliability, fault-tolerant Another requirement is the replacement of equipment damaged parts, do not need downtime, does not require replacement parts after the restart, which means the replacement parts operations can be conducted online, this can reduce the time to shutdown To the minimum. In the design of the principle of enterprise campus networks to improve network reliability, high availability principle is essential, not only requires the components redundant equipment, also urged the network link redundancy, can combine the physical layer, and link layer The third layer technology to ensure that the network may at any time and any place to provide access to information services.

3.2 scalability

The scalable network design requirements, including the switching hardware and network capacity expansion of the implementation of the new application capabilities. Core switches flexible scalability requirements: core switches should have the flexibility to expand port capacity expansion module capacity to meet the network expansion of the scale, while improving performance and meet more high-performance requirements. The ability to support new applications: products with new applications to support the technical preparation, the structure can be quickly and easily implement new applications.

3.3 scale with users

In the design of the network programme, the first is the size of the existing network to meet the needs of users, taking into account future business development, the expansion of the scale, the network should be designed with a flexible user port expansion capability. Core equipment is the hub of the network, users of the port expansion, the need for additional wiring between the edge of the Working Group of equipment, increase the edge of the equipment at the same time, the equipment required to connect the core backbone of the corresponding increase in the number of ports, the core equipment should be able to increase module To increase flexibility in the number of ports. Core of the chassis design should have a strong backplane bandwidth, more than enough slots load capacity. The switch, the core of the exchange of engine configuration should be able to meet the largest, non-blocking the port for the exchange of data packets, the expansion module does not affect the exchange of properties. Distributed by the exchange structure is to achieve the best solution to this principle, distributed switch structure to achieve the exchange of data switches parallel processing, optimizing the performance of the network, the local exchange and the exchange of the overall integration of distributed architecture to reduce the exchange of core engine The pressure. So in the design of large-scale complex network of distributed widely adopted in principle to achieve a flexible, modular switches, expansion of port capacity.

3.4 Security

Network security of the network design is very important, reasonable network security control, so that the information in the application of environmental resources and effective protection can effectively control network access and flexible implementation of network security control strategy. In the enterprise campus network, the key application servers, core network equipment, system administrators can only operate, control the power. Application client only permission to visit the sharing of resources, the network should be able to prevent any illegal operations. Network equipment in the park should be based on the agreement, based on the Mac address, based on the IP address of the packet filter control. Large-scale network in the design of the park, the son of virtual network, on the one hand can be effective isolation of the large number of broadcast network, on the other hand isolation between the sub-network communications, control access to resources, improve network security Sexual. Net in the design of the park must be stressed that the principle of network security control, so that network can be connected, but also from the second tier, third tier control network access.

3.5 manageability

Network manageability requirements: any equipment in the network can be adopted to control network management platform, network equipment, and failure by the police and so on network management platform to monitor, through the network management platform to simplify management, improve network management Efficiency.

In network design, select advanced network management software is essential. Network management software for network equipment configuration, network topology, the status of network equipment, network equipment failure incident alarm, as well as statistical analysis of network traffic, such as billing. Network management software applications can improve the efficiency of network management, network management staff to reduce the burden. Network management objective is to achieve zero-management, policy-based management, network management is through the development of a unified strategy by the management strategy for the overall control of the server. Web-based network management interface, is the development trend of network management software, flexible way to streamline the operation of the management staff. In the design of the park on the choice of network equipment for network equipment to support standard network management protocol SNMP, while supporting RMON / RMONII agreement, the core equipment requirements to support RAP (long-range analysis of port) agreement, the full implementation of the network management capabilities. In the design of the park on the principle of network equipment should be required to management, while advanced network management software can support network maintenance, monitoring, configuration, and other functions.

3.6 of the standard agreement

The adoption of network equipment technology and support standard protocol: a standard agreement to protect the user's investment, improve the interoperability of equipment. Network design used by the equipment require the use of mainstream technology, development of standard protocols, has good interoperability, the same manufacturers can support the different products, different manufacturers of products between the connected and seamless communication. In the design of the park network in principle, play different manufacturers products for advanced technology at the same time, we must emphasize the technical inspection equipment, the standard agreement, to reduce the problem of interconnection equipment, network maintenance costs, so that the user's investment has been effectively protected.

Consideration should be given the choice of whether the equipment can be upgraded, the new standards in the future, the system should be able to upgrade to the new standards. Thus focus on product manufacturers in the corresponding products and technologies in the field position and the ability to participate in standardization.

In today's world, communication technology and the rapid development of computer technology. Network design it is necessary to adapt to the trend of development of new technologies to ensure that the advanced nature of the system, we must take into account the technical maturity and lower because of new technologies and new products brought about by the premature risk factors.

4. Campus Network Solutions

Gigabit Ethernet the biggest advantages is that its existing Ethernet compatibility. With 100 M Ethernet, Gigabit Ethernet and 10 M using the same Ethernet frame format and frame size, and the same CSMA / CD agreement. This means that the majority of the Ethernet users of the existing Ethernet smooth, without interruption of the upgrade, but without adding additional protocol stack or middleware. At the same time, Gigabit Ethernet also inherited the Ethernet other advantages, such as high reliability and easy management. Backbone network in the park, now gradually occupy a major position.

Application of the campus network as a feature of most of the delay and bandwidth less sensitive, through TCP / IP "slow start" mechanism for automatic identification delay the changes, and dynamically adapt to the bandwidth provided by the TCP, and some business applications require real-time transmission Support, QoS service guarantee. This part of the current proportion of small, with teaching methods to speed up the process of modernization, multimedia courseware tools gradually universal, the gradual rich multimedia courseware, the proportion is expected to gradually increase. IP network transmission of real-time business is the main bottleneck routers used to identify routing software, computing and packet forwarding, routing due recognition, slow the speed of data transmitted, delay and delay jitter, can not guarantee quality of service (QoS ). Since the second half of 1997, some companies have launched a dedicated hardware circuit (ASIC) for routing identification, calculation and forwarding the new wire-speed routing switches. This wire-speed routing switches with the structure similar to L2 switches, routers both L3 and L2 packet forwarding function of the exchange, some of which include some manufacturers are still L4 application-level functions.

In the packet-switched IP network to provide QoS, the service must be classified, exercise classified service (CoS). Equipment manufacturers ensure that the general use of congestion management network performance, for a number of special operations to provide the bandwidth. One approach is to use RED (Random Early loss) detection and identification smart flow of transient surge, and its real distinction between the network congestion, so as to avoid network congestion. IP through from Baotou in the IPv4 services classification logo (TOS) to identify type of service (802.1 P), established that the data flow of priority, and in accordance with a priority queue algorithm to ensure that the QoS capabilities. You can also use Access Control List (ACL) definition of strategy, determine the priority of data flow. With advances in technology, predictable, high-speed IP network QoS on the ability to reach FR / ATM network similar level.

Comparative analysis of the market in a variety of L2/L3/L4 wire-speed routing switch performance, price, service on the basis of choice of the United States Lucent (Lucent)'s Cajun P550R Routing Switch a total of 11, as the campus network backbone switches. Its main technical, performance indicators are:

Backplane capacity of 45.76 Gbps

The exchange of 22.88 Gbps throughput capacity

No. 2-exchange capacity of 33,000,000 pps

Article 3 of the exchange capacity of 18,000,000 pps

A variety of L2/L3 interface module

Redundant fans, power

OpenTrunk / VLAN interoperability

CoS / QoS / RSVP support

In network design, the switch between the trunk through the Gigabit Ethernet interconnect. All switches are configuration exchange L3 engine, the implementation of distributed routing strategies, thereby reducing the Centre switches L3 routing analysis, the packets transmitted pressure and control the scope of broadcasting domain. Network design and equipment in the distribution of careful consideration of the lines and routing equipment and the physical and logical redundancy, network server group Center firewall settings and security policies.