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CLI-based Configuration Guide - Network Management and Monitoring

AR100, AR120, AR160, AR1200, AR2200, AR3200, and AR3600 V300R003

This document provides the basic concepts, configuration procedures, and configuration examples in different application scenarios of the network management feature supported by the device.

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Understanding TCP FPM

Understanding TCP FPM

Network Model

Figure 3-1  TCP FPM network model
The TCP FPM network model shown in Figure 3-1 includes the following roles:
  • Application Client: a device that provides applications to users, such as PC.
  • Application Server: a device that provides services to clients, such as file server.
  • Router: a device that collects statistics on network performance such as network delay and packet loss rate.

Working Process

Figure 3-2  TCP FPM measurement flowchart
  1. The Application Client sends a request packet, and the Router identifies that the packet is the SYN packet in the first handshake, obtains source and destination IP addresses, creates a bidirectional flow table, and records the timestamp. The Router then transmits the packet to the Application Server.
  2. After receiving the request packet, the Application Server sends a response packet. The Router identifies that the packet is the SYN-ACK packet in the second handshake based on the table, records the time, and transmits the response packet to the Application Client. In this case, TCP_SND is calculated.
  3. After receiving the response packet, the Application Client sends a packet again. The Router identifies that the packet is the ACK packet in the third handshake based on the table, and records the time. In this case, TCP_CND is calculated.
  4. The Router collects statistics on network performance such as network delay and packet loss rate for you to understand network quality.
    • TCP Server Network Delay (TCP_SND): Network delay of the server.
    • TCP Server Network Delay (TCP_SND): Network delay of the client.
    • Data Server Network Delay (DATA_SND): Response delay, that is, the time difference between the data request sent by the client and the response sent by the first server.
    • Application Delay (AD): Response delay of an application, that is, the delay generated by the application server (AD = DATA_SND – TCP_SND).
    • Packet loss rate: TCP application packet loss is calculated based on TCP retransmission. For a TCP flow, the TCP sequence numbers of retransmitted packet and lost packet are the same. That is, the packet loss rate is (the number of retransmitted packets/the number of sent packets).
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Updated: 2019-03-06

Document ID: EDOC1100069336

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