Huawei DR814Q User Manual
Page 52
User Manual
Aolynk DR814Q ADSL2+ Broadband Router
5 Advanced Configuration
47
Service type
Description
VBR-rt
(real-time
variable bit
rate)
Sensitive to delay and jitter of data flow. Similar to CBR except that
they are delay- and jitter-sensitive. VBR-rt services allow limited
burst. The transmission rate on source side can be different at
different time. The parameters required for VBR-rt service
application include PCR, SCR, and MBS or BT. Typical VBR-rt
applications are voice and interactive video services and IPTV.
VBR
(non-real-time
variable bit
rate)
Suitable for bursting non-real-time services. Compared to VBR-rt, a
distinct feature of VBR services is that demands of real-time are not
so crucial, and the priority for service data processed on the
network side is also lower than that of VBR-tithe parameters
required by VBR services include PCR, SCR, and MBS (or BT), the
same as that of VBR-rt.
Keep 0 unchanged for those options unrelated to the configuration. As shown in Figure
5-5, if VBR-rt is selected from the ATM Traffic Class drop-down list, you need to set
values for Peak Cell Rate, Max Burst Size, and Sustainable Cell Rate and leave 0 in the
Burst Tolerance and Minimum Cell Rate text boxes.
An example is taken to explain how to configure ATM QoS parameters. You must
configure to meet the following requirements for the ATM QoS parameters of your
DR814Q to take effect:
z
The digital subscriber line access multiplexer (DSLAM) has a relax control or even
no control over the LAN port and PVC upstream rates, entirely depending on the
ADSL line. The actual upstream rate of ADSL can be 896 Kbps at most if DSLAM
supports ADSL only.
z
Multiple PVCs are configured on a single ADSL line.
Suppose that:
The downstream rate of each PVC is strictly specified by the central office (CO),
whereas the upstream rates of the PVCs are all configured to 896 Kbps.PVC1 and
PVC2 are configured on each ADSL line, among which you use PVC1 to access the
Internet and PVC2 to provide video chatting service.
Analysis:
Although an upstream rate of 896 Kbps is configured to PVC1 and PVC2 respectively
at the CO, audio and video services carried out over them may still be interfered. For
example, an uploading service, which consumes a bandwidth lager than 500 Kbps,
bursts on PVC1 when a video conference, which requires a minimum bandwidth of 384
Kbps for both upstream and downstream rates, is carried out over PVC2. This results in
the available bandwidth for PVC2 less than 384 Kbps, thus causing the audio and video
service interrupted.
To avoid this, configure the QoS parameters as follows:
1)
Click
the [QoS Config] page of PVC2.