Network test principle and classification

The network is developing rapidly, and more and more users are using the network. With the increase of users ' dependence on the network, the normal operation of the network becomes more and more important. Network paralysis has become a key problem in the field of data communication, in order to ensure the normal operation of the network, all faults must be solved quickly and efficiently. In the whole process of network installation, maintenance, management and fault diagnosis, the problem of network testing is running through. It can be said that testing for the healthy operation of the network has brought an effective solution.

Ethernet Test

As more and more multimedia, video and image transmission technologies are used in network applications, the bandwidth requirements of the network are very tight. When the network load is very light, the efficiency of information transmission is relatively high, when the traffic increases quickly, the collision increases a lot and causes the network performance to drop. Generally speaking, network performance is related to the devices connected to the network, there may be several reasons for Ethernet blocking.

A handful of high-speed network devices on the network may consume a large amount of network bandwidth. For example, a busy server or engineering workstation.

Too many sites on the network are the same number of users who want to share the bandwidth, and the effect is the same as the results of a few high-speed network devices. Some applications in network that aggravate network traffic

The interaction between users and the transmission of files has a completely different demand for the network. Interactive applications require a lower latency, and file transmission requires a high utilization of bandwidth and bandwidth.

The need for bandwidth is caused by a variety of reasons, and using a switch is more effective than using a device such as a hub to solve a blocking problem. Testing can help users determine the real cause of network performance degradation, providing quantitative help on whether a network needs a switch and how to use a switch. For example, the network statistics function of the test instrument is used to check the utilization of the network segment, the collision rate, the error rate and the number of broadcast traffic.

If high utilization is caused by repeated errors due to an error, the error type and source can be identified using the instrument's error statistics function. When considering the use of switches, it is important to know which sources are causing high traffic. The "Maximum sender" and "maximum receiver" functions of the test instrument can easily and quickly inform the relevant information. Depending on the information, you can make a decision, such as which user needs to be specifically assigned to a particular exchange port.

It is also helpful to know about the operation of the Protocol. For example, which protocol to run the most, and related sites and network equipment have those. Some vendor testers (such as Fluke Lanmeter Network Tester) data logging capabilities, as well as network health scanning (Health Scan) software can be a network segment for a period of time (such as 24 hours) of monitoring records, so that the performance of the network and operating conditions to make a basic evaluation.

With the information obtained from the instrument, the user can decide whether to use the switch. The ideal design may be that each device has a path that is directly connected to the other required devices. Obviously in the current environment this is unrealistic or difficult to achieve. Therefore, careful and reasonable use of the switch can improve the performance of the network. It is not possible to improve network performance simply by replacing a device with a switch that is being used.

More and more users are first considering using switches rather than routers to separate the networks. However, how well the switches are installed, whether the switch is faulty, or how to test the switch is a problem. With switch Wizard (Switch test pack), network managers can access the network in a switched environment in any part of the network, and fully see the internal situation of the exchanger through SNMP and rmon information. You can also monitor the statistics of multiple switch ports and provide mirrored broadcast statistics and error statistics for any given port, and the analysis of the ports identifies the MAC addresses that are connected on each switch port. The Switch Wizard can also analyze the Fast Ethernet and FDDI port statistics in the switch. These functions are not possible on the protocol analyzer. In a complex switched network environment, switch Wizand can greatly help network managers to maintain and monitor the operation of the network.

ATM Network test

The quality of the copper media access circuit between ATM users and service providers varies greatly, from the quality of the approach light to the only voice service, so the service provider generally guarantees bit error rate (BER) for End-to-end ATM connections.

Data detection and retransmission is no longer a wide area network (WAN), such as a X.25 task, but a client-side transport layer. It can compose 32 ATM components into a TCP/IP packet, and a bit error in the ATM will cause two full TCP/IP packets or 64 ATM bytes to be sent back. For noisy circuits, there will be a snowball effect, the data will cause the actual connection between the site blocking.

Traditional bit-error-rate testing (BERT)

Copper or optical cables are used when additional access connections are added between the user's site and the network edge switch of the business provider. The cable path will be from the user room of the demarcation point to the nearest Central Bureau cable rack. The cable is installed by the local Exchange bureau and tested for physical media to ensure reliable transmission of the user's business. Tests conducted by the local Exchange bureau are called bit-error-rate testing (BERT). The Bert test can be performed by the installer at the user's station or by the technician at the Central Bureau.

Before testing, send and receive loops back at one end of the cable, and the transceiver of the tester is connected to the back end of the cable. The tester sends a sequential binary random code, which is received by the loop back of the circuit at the receiving port. The tester compares the sending bit stream to the receiving bit stream, and counts the bit error (0 turns to 1 or 1 to 0). RER is the ratio of the number of error bits to the total number of bits transmitted, typically Bert tests take some time (15 minutes to 24 hours) to obtain a specific BER value.