Type of Service (TOS) Settings

The TOS Configuration object is used to configure the Type of Service (TOS) parameters for an IP Profile. Type of Service is configured in SIP. The IMG 2020 supports RFC 1349 which is Type Of Service Support. When making an IP Call the path that the call follows varies depending on the quality of service the circuit provides. There are different factors that are looked at and decided on when making the decision of which path to take. Some of the decisions are as follows:

• What are the call setup charges in the circuit?

• What is the throughput of the circuit?

• What is the delay in the circuit?

• What is the reliability of the circuit?

The optimal path to follow depends largely on the user. Type of service configuration gives user the ability to decide which circuits will get high or normal throughput, high or normal delay, and high or normal reliability.

Web GUI Page

Dialogic > Profiles > IP Profiles > IP Profile > New TOS Settings

Maximum Objects

One Type of Service (TOS) object per IP Profile object.

Related Topics and Dependencies

IP Profile 

Field Descriptions

Within the RTP packet are 8 bits of information reserved to the type of service. They are broken up as shown in the table below

The fields below fill in this ethernet packet depending on the selections made in the TOS Settings Pane

Precedence

The first three bits of the RTP packet are a bit mask and specify the precedence varying from 0 to 7. The precedence field denotes importance or priority of the RTP packet. This field does not affect the route. The precedence field affects different aspects of packet forwarding. The precedence field has a drop down menu with the following selections:

• Routine

• Priority

• Immediate

• Flash

• Flash Override

• CRITIC/ECP

• Internetwork control

• Network Control 

TOS Fields: (Type of Service)

The next four (Delay, Throughput, Reliability, and Cost) are all Types Of Service and specify how the network should make trade-offs between throughput, delay, reliability, and cost.

Delay

• Normal Delay (default)

• Low Delay

Throughput

• Normal Throughput (default)

• High Throughput

Reliability

• Normal Reliability (default)

• High Reliability

Cost

• Normal Cost (default)

• Low Cost

Congestion: (Must be Zero)

The last is considered MBZ (Must be Zero). This value is always 0.

RTP TRACE

Below is an RTP Trace of the TOS feature.

Mapping Differentiated Services Code Point (DSCP) to Type of Service (TOS)

DSCP is a newer model in which traffic is treated with priorities based on the Type Of Services field. The IMG 2020 does not support the DSCP model. However, the DSCP model can be mapped to values used in the TOS model. Below are tables on how the values are mapped. The mappings are only valid for RTP packets and does not affect signaling packets.