![](/images/new-backgrounds/1189361/189361227x1.webp)
Chapter 4: Web Configuration
Quality of Service
QoS (Quality of Service) is an
There have been two generations of quality of service architectures in the Internet. The interpretation of the Type of Service Octet in the Internet Protocol header varies between these two generations.
The First generation: Precedence and type of service bits
The refined definition of the initial Type of Service Octet looks like this:
2^7 | 2^6 | 2^5 | 2^4 | 2^3 | 2^2 | 2^1 | 2^0 |
| Precedence |
|
| Type of Service Field |
|
| |
|
|
|
|
|
|
|
|
The Second generation: Differentiated services code point
The Differentiated Service Code Point is a selector for router's
2^7 | 2^6 | 2^5 | 2^4 | 2^3 | 2^2 | 2^1 | 2^0 |
| Differentiated Services Code Point |
| ECT | CE | |||
|
|
|
|
|
|
|
|
The fields ECT and CE are nothing to do with quality of service. They are spare bits in the IP header used by Explicit Congestion Notification. As can be seen, the DSCP totally overlaps the old Precedence field. So if values of DSCP are carefully chosen then backward compatibility can be achieved. This leads to the notions of "class", each class being the group of DSCP with the same Precedence value. Values within a class would offer similar network services but with slight differences. Classes were initially defined as:
DSCP | Precedence | Purpose |
0 | 0 | Best effort |
8 | 1 | Class 1 |
16 | 2 | Class 2 |
24 | 3 | Class 3 |
32 | 4 | Class 4 |
40 | 5 | Express forwarding |
48 | 6 | Control |
56 | 7 | Control |
Now, DSCP is what we are using for the QoS configuration on this device.
Among the classes you will see on the webpage, the BE (Best Effort) class possesses no guaranteed rates; the CS (Class Selector) values enable backward compatibility with the older
You can start to configure the Bridge QoS/IP QoS rules on the Quality of Service webpage for your router.