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NE40E V800R010C10SPC500 Feature Description - System Monitor 01

This is NE40E V800R010C10SPC500 Feature Description - System Monitor
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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).
TWAMP Fundamentals

TWAMP Fundamentals

Implementation

The Two-Way Active Measurement Protocol (TWAMP) defines a method for measuring round-trip IP network performance between two TWAMP-capable devices. Figure 7-1 shows how TWAMP is implemented.
  • The performance management system instructs the control-client to establish a test session with a specific TWAMP server.
  • The control-client establishes and completes the test session.
  • The performance management system collects statistics during the test are saved.
Figure 7-1 TWAMP implementation

TWAMP collects statistics about the delay, jitter, and packet loss rate.
  • The delay and jitter are calculated based on timestamps. The session-sender sends a probe carrying a sending timestamp T0, and the reflector replies with a response probe carrying a receiving timestamp T1 and a responding timestamp T2. After receiving the response probe, the session-sender records the receiving timestamp T3. The delay and jitter during a single period are calculated based on the four timestamps.
  • The packet loss rate is calculated based on the serial numbers (starting from 0) carried in probes. The session-sender sends a probe with a serial number, and the reflector replies with a response probe with the same serial number. Each time the session-sender sends a probe or the reflector replies with a response probe, the serial number increases by 1. The packet loss rate is calculated based on the two rows of serial numbers.

Intercommunication Model

TWAMP uses the client/server mode and defines four logical entities, as shown in Figure 7-2.
  • Control-client: establishes, starts, and stops a test session and collects statistics.
  • Session-sender: proactively sends probes for performance statistics after being notified by the control-client.
  • Server: responds to the control-client's request for establishing, starting, or stopping a test session.
  • Session-reflector: replies to the probes sent by the session-sender with response probes after being notified by the server.
Figure 7-2 Typical TWAMP logical architecture

To facilitate implementation, TWAMP unifies the four logical entities, as shown in Figure 7-3. Control signals are exchanged between the control-client and server through a TCP connection; probes are exchanged between the session-sender and session-reflector through a UDP connection. The control-client and server establish and start a test session. Once a test session starts, the control-client and server notify the session-sender and session-reflector respectively of the session information and allow the session-sender to send probes and the session-reflector to respond to the probes.

Figure 7-3 Typical TWAMP implementation architecture

NOTE:

On a live network, if a network element (NE) functions as a server and session-reflector alone, the NE participates in TWAMP session establishment and probe exchanges but does not compile statistics. If a device or tester functions as the control-client and session-sender, the device or tester proactively establishes a TWAMP session for statistics collection. Users manage the control-client alone to rapidly obtain statistics about the performance of the entire IP network.

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Updated: 2019-01-03

Document ID: EDOC1100055050

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