The Type of Service (ToS), now known as Differentiated Services (DS), defines a mechanism for assigning a priority to each IP packet as well as a mechanism to request specific treatment such as high throughput, high reliability or low latency.
The 8 bit ToS field originally defined a mechanism for assigning priority to each IP packet as well as a way to request treatment such as high throughput, high reliability or low latency.
The definition of this field was changed in RFC 2474 . The 6 bit field is now called the DS (Differentiated Services) field and the upper 6 bits contain a value called the Differentiated Services Code Point (DSCP). The remaining two least significant bits are used for Explicit Congestion Notification (ECN).
The ToS field is now used by Differentiated Services and is called the Differentiated Services Code Point (DSCP) .
| DSCP IP precedence | User priority |
|---|---|
|
0–7 |
0 |
|
8–15 |
1 |
|
16–23 |
2 |
|
24–31 |
3 |
|
32–39 |
4 |
|
40–47 |
5 |
|
48–55 |
6 |
|
56–63 |
7 |