Example: Configuring Priority Scheduling on SONET/SDH OC48/STM16 IQE PICs
In the following example, ef is an expedited forwarding
traffic queue; af_01, af_02, af_03, andaf_04 are assured forwarding traffic queues; be is a best effort forwarding queue; and nc is
a network control traffic queue.
[edit class-of-service]
traffic-control profiles tcp {
shaping-rate 300M;
}
[edit class-of-service]
interfaces {
so-2/2/0 {
unit 0 {
output-traffic-control-profiles tcp;
}
}
schedulers {
ef {
transmit-rate percent 50 rate-limit;
buffer-size percent 5;
priority strict-high;
}
nc {
transmit-rate percent 0;
excess-rate percent 5;
buffer-size percent 5;
priority low;
excess-priority high;
}
af_01 {
transmit-rate percent 0;
excess-rate percent 20;
buffer-size percent 18;
priority low;
excess-priority low;
}
af_02 {
transmit-rate percent 0;
excess-rate percent 35;
buffer-size percent 18;
priority low;
excess-priority low;
}
af_03 {
transmit-rate percent 0;
excess-rate percent 30;
buffer-size percent 18;
priority low;
excess-priority low;
}
af_04 {
transmit-rate percent 0;
excess-rate percent 9;
buffer-size percent 18;
priority low;
excess-priority low;
}
be {
transmit-rate percent 0;
excess-rate percent 1;
buffer-size percent 18;
priority low;
excess-priority low;
}
}
Queue |
Priority |
Transmit Rate |
Excess Priority on the SONET/SDH OC48/STM16 IQE PIC (Mapped to Guaranteed Priority) |
Excess Rate on the SONET/SDH OC48/STM16 IQE PIC (Mapped to Transmit Rate) |
Input (Mbps) |
Output (Mbps) |
|---|---|---|---|---|---|---|
ef |
Strict-high |
50 (50% of PIR=150 Mbps) |
Not applicable |
Not applicable |
300 |
150 |
nc |
Low |
0 |
Excess high |
5 |
300 |
150 |
af_01 |
Low |
0 |
Excess low |
20 |
300 |
0 |
af_02 |
Low |
0 |
Excess low |
35 |
300 |
0 |
af_03 |
Low |
0 |
Excess low |
30 |
300 |
0 |
af_04 |
Low |
0 |
Excess low |
9 |
300 |
0 |
be |
Low |
0 |
Excess low |
1 |
300 |
0 |
As shown in Table 1, the ef queue takes precedence over all queues and consumes 150
Mbps (50 percent of the PIR; that is, half of 300 Mpbs) bandwidth.
The remaining 150 Mbps is rate limited. The af_01, af_02, af_03, af_04 and the be queues do not get any bandwidth.
Because the rate limit is not configured on the nc queue, and it has the excess high priority, the nc queue
consumes the remaining bandwidth of 150 Mbps.