administration.fm
A31003-S2000-M102-3-76A9, 08/07/2009
Asterisk - OpenStage Family, Administration Manual
3-13
Administration
IP Network Parameters
3.3
IP Network Parameters
3.3.1
Quality of Service (QoS)
The QoS technology based on layer 2 and the two QoS technologies Diffserv and TOS/IP Pre-
cedence based on layer 3 are allowing the VoIP application to request and receive predictable
service levels in terms of data throughput capacity (bandwidth), latency variations (jitter), and
delay.
3.3.1.1
Layer 2 / 802.1p
QoS on layer 2 is using 3 Bits in the 802.1q/p 4-Byte VLAN tag which has to be added in the
Ethernet header.
The CoS (class of service) value can be set from 0 to 7. 7 is describing the highest priority and
is reserved for network management. 5 is used for voice (RTP-streams) by default. 3 is used
for signaling by default.
Data required
•
Layer 2
: Activates or deactivates QoS on layer 2.
Value range: "Yes", "No".
Default: "Yes".
•
Layer 2 voice
: Sets the CoS (Class of Service) value for voice data (RTP streams).
Value range: 0-7.
Default: 5.
•
Layer 2 signalling
: Sets the CoS (Class of Service) value for signaling.
Value range: 0-7.
Default: 3.
•
Layer 2 default
: Sets the default CoS (Class of Service) value.
Value range: 0-7.
Default: 0.
>
Layer 2 and 3 QoS for voice transmission can be set via LLDP-MED (see Section
3.19.3, “LLDP-MED”). If so, the value can not be changed by any other interface.
Three Bits Used for CoS
(User Priority)
PREAM.
SFD
DA
SA
TAG
4 Bytes
PT
DATA
FCS