Configuring The One-Way Frame Delay Measurement In A Vlan; Establishing The Configuration Task - Huawei Quidway S3700 Series Configuration Manual

Quidway S3700 Series Ethernet Switches
Configuration Guide - Reliability
The two-way frame delay measurement is generally performed on end-to-end MEPs. A MEP
receives a DM frame and returns a DMR frame to carry out the two-way frame delay
measurement. After the two-way frame delay measurement is configured, a MEP periodically
sends DM frames with the TxTimeStampf value (timestamp at the time of sending the DM
frame). After receiving the DM frame, the remote MEP adds the RxTimeStampf value
(timestamp at the time of receiving the DM frame) to the DM frame, generates a DMR frame
with the TxTimeStampb value (timestamp at the time of sending the DMR frame), and sends
the message to the requesting MEP. Every field in the DM frame is copied to the DMR frame
except that the source and destination MAC addresses are swapped and the message type is
changed from DM to DMR. Upon receiving the DMR frame, the requesting MEP calculates the
two-way frame delay based on the following formula:
Two-way frame delay = (RxTimeb - TxTimeStampf) - (TxTimeStampb - RxTimeStampf)
The frame delay variation, namely, frame jitter, can be calculated based on the frame delay.
Jitter: is used as a measure of the variability over time of the frame delay across a network, and
is the absolute difference value between two delays.
5.3 Configuring the One-way Frame Delay Measurement in
a VLAN
You can configure the one-way frame delay measurement in the VLAN bound to an MA and
estimate the quality of services based on the calculated one-way frame delay.

5.3.1 Establishing the Configuration Task

Before configuring the one-way frame delay measurement, familiarize yourself with the
applicable environment, complete the pre-configuration tasks, and obtain the required data. This
can help you complete the configuration task quickly and accurately.
Applicable Environment
You can configure the one-way frame delay measurement to collect statistics about the delay in
bidirectional service traffic transmission.
The one-way frame delay measurement is commonly performed on point-to-point MEPs. After
a MEP receives a Delay Measurement (DM) message from the remote MEP, it calculates the
time delay experienced across the network by comparing the timestamp in the DM frame and
the local time. During the one-way frame delay measurement, ensure that clocks on MEPs are
synchronous.
Pre-configuration Tasks
Before configuring the one-way delay measurement in the VLAN, complete the following tasks:
l
Issue 01 (2011-10-26)
NOTE
Before enabling the one-way delay measurement in the VLAN on the local device, you must configure the
DM frame reception function on the remote device.
Configuring synchronize clock, For the configuration procedure, see NTP Configuration
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5 ITU-T Recommendation Y.1731 Configuration
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