QoS Scheduler Policies
Quality of Service Guide 507
The priority 1 “above-cir” scheduling loop has a special two tier strict distribution function.
The high priority level 1 “above-cir” distribution is weighted between all queues and
schedulers attached to level 1 for “above-cir” bandwidth. The low priority distribution for
level 1 “above-cir” is reserved for all orphaned queues and schedulers on the egress port.
Orphans are queues and schedulers that are not explicitly or indirectly attached to the port
scheduler through normal parenting conventions. By default, all orphans receive bandwidth
after all parented queues and schedulers and are allowed to consume whatever bandwidth is
remaining. This default behavior for orphans can be overridden on each port scheduler policy
by defining explicit orphan port parent association parameters.
Ultimately, any bandwidth allocated by the port scheduler is given to a child queue. The
bandwidth allocated to the queue is converted to a value for the queue’s PIR (maximum rate)
setting. This way, the hardware schedulers operating at the egress port level will only
schedule bandwidth for all queues on the port up to the limits prescribed by the virtual
scheduling algorithm.
The following lists the bandwidth allocation sequence for the port virtual scheduler:
1. Priority level 8 offered load up to priority CIR
2. Priority level 7 offered load up to priority CIR
3. Priority level 6 offered load up to priority CIR
4. Priority level 5 offered load up to priority CIR
5. Priority level 4 offered load up to priority CIR
6. Priority level 3 offered load up to priority CIR
7. Priority level 2 offered load up to priority CIR
8. Priority level 1 offered load up to priority CIR
9. Priority level 8 remaining offered load up to remaining priority rate limit
10. Priority level 7 remaining offered load up to remaining priority rate limit
11. Priority level 6 remaining offered load up to remaining priority rate limit
12. Priority level 5 remaining offered load up to remaining priority rate limit
13. Priority level 4 remaining offered load up to remaining priority rate limit
14. Priority level 3 remaining offered load up to remaining priority rate limit
15. Priority level 2 remaining offered load up to remaining priority rate limit
16. Priority level 1 remaining offered load up to remaining priority rate limit
17. Priority level 1 remaining orphan offered load up to remaining priority rate limit
(default orphan behavior unless orphan behavior has been overridden in the
scheduler policy)
To Next Page
Loading...
