Type of Service (ToS) - a byte containing a set of criteria that determine the type of service for IP packets. The field in the IPv4 packet header, which has acquired various objectives over the years, is described in five RFCs . Currently, the ToS field is called the differentiated services field and has 6 bits of the DiffServ Code Point (DSCP) field and 2 bits of the Explicit Congestion Notification field.
The type of service allows you to prioritize IP traffic on network routers in order to ensure high quality data transfer
Byte bitwise (0 - senior, 7 - junior) :
- 0-2 - precedence of this IP segment
- 3 - requirement for the delay time of the IP segment transmission (0 - normal, 1 - low delay)
- 4 - requirement for throughput of the route along which the IP segment should be sent (0 - low, 1 - high throughput)
- 5 - requirement for reliability of the IP segment transmission (0 - normal, 1 - high reliability)
- 6-7 - ECN - explicit delay message (IP flow control).
| 0 | one | 2 | 3 | four | five | 6 | 7 |
|---|---|---|---|---|---|---|---|
| A priority | D | T | R | ECN | |||
In practice, in most IP protocol implementations, this field is almost always 0.
See also
- Diffserv code point