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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).
Function Implementation

Function Implementation

Function Overview

IP FPM measures the packet loss rate and delay of multipoint-to-multipoint (MP2MP) service flows traveling across the transit network.

Table 4-1 lists the IP FPM types and usage scenarios.
Table 4-1  IP FPM types

Type

Scenario

Continuous end-to-end performance measurement

To detect network performance degradation in a timely manner, use this mode. This mode displays continuous network running status.

On-demand end-to-end performance measurement

When network performance degrades or users want to monitor the performance of a specified service flow, use this mode. This mode displays detailed performance statistics in recent time.

The device supports the following IP FPM functions:
  • Packet loss measurement
    • Point-to-point packet loss measurement measures packet loss on a link between two devices to determine the link quality.

    • Multipoint-to-multipoint packet loss measurement measures packet loss on links between multiple devices to determine the link quality.

  • Delay measurement
    • Point-to-point two-way delay measurement measures two-way delay on a link between two devices to determine the link quality.

Implementation

On a transit network with boundaries, flows enter and leave the network through some boundary devices. In Figure 4-3, the number of packets entering the ingress interfaces on Routers is PI, and the number of packets leaving the egress interfaces on Routers is PE.

Figure 4-3  IP FPM measurement diagram

In a specified period, the number of lost packets is the difference between the number of packets entering a transit network and the number of packets leaving the transit network.
  • The total number of ingress packets is PI = PI(1) + PI(2) + PI(3).
  • The total number of egress packets is PE = PE(1) + PE(2) + PE(3).

Within a measurement interval, the delay is the time difference between a flow enters and leaves a network.

Packet loss measurement

Packet loss measurement calculates the difference between the number of packets entering a transit network and the number of packets leaving the transit network within a measurement interval.

Figure 4-4 shows a typical network end-to-end performance measurement model. Service packets enter the network from RouterA and leave the network from RouterB.
Figure 4-4  Packet loss measurement diagram

  1. t0: RouterA sets the packet loss color bit to 1 for incoming service packets in the first interval and starts counting all service packets with the packet loss color bit as 1.
  2. t1: RouterB starts receiving service packets with the packet loss color bit as 1 in the first interval and starts counting these service packets.
  3. t2: RouterA finishes counting the incoming service packets with the packet loss color bit as 1 in the first interval and obtains the total number of these service packets PI(1). RouterA then sets the packet loss color bit to 0 for incoming service packets in the second interval and starts counting all service packets with the packet loss color bit as 0.
  4. t3: RouterB finishes receiving service packets with the packet loss color bit as 1 in the first interval and obtains the total number of these service packets PE(2).
    NOTE:
    RouterB starts receiving service packets with the packet loss color bit as 1 from t1. When the internal timer passes a measurement interval (at t3), RouterB determines that receiving of the service packets with the packet loss color bit as 1 in this interval is finished, but does not determine the finish of service packet receiving when it receives a service packet with a non-1 color bit. This mechanism prevents the impact of packet unsequencing on service packet statistics, to ensure the accurate service packet counting within an interval.
  5. t4: RouterA sets the packet loss color bit to 1 for incoming service packets in the third interval and starts counting all service packets with the packet loss color bit as 1.
  6. t5: RouterB starts receiving service packets with the packet loss color bit as 1 in the third interval and starts counting these service packets.

RouterB obtains the number of received service packets with the packet loss color bit as 1 in the first interval any time between t3 and t5. The formula is LostPacket = PI(1) - PE(2).

Delay measurement

Delay is the difference between a service flow enters and leaves a network.

In IP FPM, a device samples service packets, records the actual forwarding time of service packets, and calculates the transmission delay of the service flow.
Figure 4-5  Delay measurement diagram

Figure 4-5 shows the delay measurement diagram.
  • For packets sent from RouterA to RouterB:
    • t1: RouterA sets the delay color bit to 1 for specified incoming service packets and obtains the timestamp t1.
    • t2: RouterB starts receiving the service packets with the delay color bit as 1 and obtains the timestamp t2.
  • For packets sent from RouterB to RouterA:
    • t3: RouterB sets the delay color bit to 1 for specified incoming service packets and obtains the timestamp t3.
    • t4: RouterA starts receiving the service packets with the delay color bit as 1 and obtains the timestamp t4.

The two-way delay is: 2d = (t2 - t1) + (t4 - t3) = (t4 - t1) - (t3 - t2)

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Updated: 2019-03-06

Document ID: EDOC1100069336

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